Title: CSS Text Module Level 3
Shortname: css-text
Level: 3
Status: ED
Work Status: Refining
Group: csswg
ED: https://drafts.csswg.org/css-text-3/
TR: https://www.w3.org/TR/css-text-3/
Previous version: https://www.w3.org/TR/2019/WD-css-text-3-20191113/
Previous Version: https://www.w3.org/TR/2018/WD-css-text-3-20181212/
Previous Version: https://www.w3.org/TR/2018/WD-css-text-3-20181206/
Previous Version: https://www.w3.org/TR/2018/WD-css-text-3-20180920/
Previous Version: https://www.w3.org/TR/2017/WD-css-text-3-20170822/
Previous Version: https://www.w3.org/TR/2013/WD-css-text-3-20131010/
Previous Version: https://www.w3.org/TR/2012/WD-css3-text-20121113/
Issue Tracking: Tracker http://www.w3.org/Style/CSS/Tracker/products/10
Test Suite: http://test.csswg.org/suites/css3-text/nightly-unstable/
Editor: Elika J. Etemad / fantasai, Invited Expert, http://fantasai.inkedblade.net/contact, w3cid 35400
Editor: Koji Ishii, Invited Expert, kojiishi@gluesoft.co.jp, w3cid 45369
Editor: Florian Rivoal, Invited Expert, https://florian.rivoal.net, w3cid 43241
Abstract: This CSS module defines properties for text manipulation and specifies their processing model. It covers line breaking, justification and alignment, white space handling, and text transformation.
At Risk: the ''full-width'' value of 'text-transform'
At Risk: the ''full-size-kana'' value of 'text-transform'
At Risk: the <length> values of the 'tab-size' property
At Risk: the 'text-justify' property
At Risk: the percentage values of 'word-spacing'
At Risk: the 'hanging-punctuation' property
At Risk: Writing-system specific adjustments to line-breaking
At Risk: Trimming trailing Ogham space marks
Ignored Vars: letter-spacing
Status Text: This publication partially addresses the issues in the disposition of comments since the October 2013 Last Call Working Draft, and, while a marked improvement over the previous draft, is not considered to be entirely up-to-date at the time of publication. A completed dispostion of comments and corresponding draft will be published once the issues are fully addressed and reviewed by the CSSWG and Internationalization WG.
WPT Path Prefix: /css/css-text/

spec:css-display-3; type:property; text:display
spec:css-fonts-4; type:property; text:font-feature-settings

Introduction

This module describes the typesetting controls of CSS; that is, the features of CSS that control the translation of source text to formatted, line-wrapped text. Various CSS properties provide control over case transformation, white space collapsing, text wrapping, line breaking rules and hyphenation, alignment and justification, spacing, and indentation.

Module Interactions

This module, together with [[CSS-TEXT-DECOR-3]], replaces and extends the text-level features defined in [[!CSS2]] chapter 16.

In addition to the terms defined below, other terminology and concepts used in this specification are defined in [[!CSS2]] and [[!CSS-WRITING-MODES-3]].

Value Definitions

Languages and Typesetting

Authors should accurately language-tag their content for the best typographic behavior. Many typographic effects vary by linguistic context. Language and writing system conventions can affect line breaking, hyphenation, justification, glyph selection, and many other typographic effects. In CSS, language-specific typographic tailorings are only applied when the content language is known (declared). Therefore, higher quality typography requires authors to communicate to the UA the correct linguistic context of the text in the document. The content language of an element is the (human) language the element is declared to be in, according to the rules of the document language. Note that it is possible for the content language of an element to be unknown-- e.g. untagged content, or content in a document language that does not have a language-tagging facility is considered to have an unknown content language. Note: Authors can declare the [=content language=] using the global lang attribute in HTML or the universal xml:lang attribute in XML. See the rules for determining the content language of an HTML element in [[HTML]], and the rules for determining the content language of an XML element in [[XML10]]. The [=content language=] an element is declared to be in also identifies the specific written form of that language used in that element, known as the content writing system. Depending on the [=document language=]'s facilities for identifying the [=content language=], this information can be explicit or implied. See the normative [[#script-tagging]]. Note: Some languages have more than one writing system tradition; in other cases a language can be transliterated into a foreign writing system. Authors should subtag such cases so that the UA can adapt appropriately.

Characters and Letters

The basic unit of typesetting is the character. However, because writing systems are not always as simple as the basic English alphabet, what a character actually is depends on the context in which the term is used. For example, in Hangul (the Korean writing system), each square representation of a syllable (e.g. 한=Han) can be considered a character. However, the square symbol is really composed of multiple letters each representing a phoneme (e.g. ㅎ=h, ㅏ=a, ㄴ=n) and these also could each be considered a character.

A basic unit of computer text encoding, for any given encoding, is also called a character, and depending on the encoding, a single encoding character might correspond to the entire pre-composed syllabic character (e.g. 한), to the individual phonemic character (e.g. ㅎ), or to smaller units such as a base letterform (e.g. ㅇ) and any combining marks that vary it (e.g. extra strokes that represent aspiration).

In turn, a single encoding character can be represented in the data stream as one or more bytes; and in programming environments one byte is sometimes also called a character.

Therefore the term character is fairly ambiguous where technical precision is required.

For text layout, we will refer to the typographic character unit as the basic unit of text. Even within the realm of text layout, the relevant character unit depends on the operation. For example, line-breaking and letter-spacing will segment a sequence of Thai characters that include U+0E33 THAI CHARACTER SARA AM differently; or the behaviour of a conjunct consonant in a script such as Devanagari may depend on the font in use. So the typographic character represents a unit of the writing system—such as a Latin alphabetic letter (including its diacritics), Hangul syllable, Chinese ideographic character, Myanmar syllable cluster—that is indivisible with respect to a particular typographic operation (line-breaking, first-letter effects, tracking, justification, vertical arrangement, etc.). word-break/word-break-break-all-007.html word-break/word-break-break-all-008.html Unicode Standard Annex #29: Text Segmentation defines a unit called the grapheme cluster which approximates the typographic character. A UA must use the extended grapheme cluster (not legacy grapheme cluster), as defined in [[!UAX29]], as the basis for its typographic character unit. However, the UA should tailor the definitions as required by typographic tradition since the default rules are not always appropriate or ideal-- and is expected to tailor them differently depending on the operation as needed. line-breaking/line-breaking-013.html line-breaking/line-breaking-014.html

Note: The rules for such tailorings are out of scope for CSS.

A typographic letter unit or letter for the purpose of this specification is a typographic character unit belonging to one of the Letter or Number general categories in Unicode. [[!UAX44]] See Character Properties for how to determine the Unicode properties of a typographic character unit.

The rendering characteristics of a typographic character unit divided by an element boundary is undefined. Ideally each component should be rendered according to the formatting requirements of its respective element’s properties while maintaining correct shaping and positioning of the typographic character unit as a whole. However, depending on the nature of the formatting differences between its parts and the capabilities of the font technology in use, this is not always possible. Therefore such a typographic character unit may be rendered as belonging to either side of the boundary, or as some approximation of belonging to both. Authors are forewarned that dividing grapheme clusters or ligatures by element boundaries may give inconsistent or undesired results.

Text Processing

Transforming Text

Case Transforms: the 'text-transform' property

    Name: text-transform
    Value: none | [capitalize | uppercase | lowercase ] || full-width || full-size-kana
    Initial: none
    Applies to: inline boxes
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    

This property transforms text for styling purposes. It has no effect on the underlying content, and must not affect the content of a plain text copy & paste operation. Note: The 'text-transform' property only affects the presentation layer; correct casing for semantic purposes is expected to be represented in the source document. text-transform/text-transform-copy-paste-001-manual.html

Values have the following meanings:

none

No effects. text-transform/text-transform-none-001.xht text-transform-004.xht

capitalize

Puts the first typographic letter unit of each word, if lowercase, in titlecase; other characters are unaffected. text-transform/text-transform-capitalize-001.html text-transform/text-transform-capitalize-003.html text-transform/text-transform-capitalize-005.html text-transform/text-transform-capitalize-007.html text-transform/text-transform-capitalize-009.html text-transform/text-transform-capitalize-010.html text-transform/text-transform-capitalize-011.html text-transform/text-transform-capitalize-014.html text-transform/text-transform-capitalize-016.html text-transform/text-transform-capitalize-018.html text-transform/text-transform-capitalize-020.html text-transform/text-transform-capitalize-022.html text-transform/text-transform-capitalize-024.html text-transform/text-transform-capitalize-026.html text-transform/text-transform-capitalize-028.html text-transform/text-transform-capitalize-030.html text-transform/text-transform-capitalize-031.html text-transform/text-transform-capitalize-032.xht text-transform-001.xht text-transform-cap-001.xht text-transform-cap-002.xht text-transform-cap-003.xht

uppercase

Puts all letters in uppercase. text-transform/text-transform-uppercase-101.xht text-transform/text-transform-upperlower-001.html text-transform/text-transform-upperlower-003.html text-transform/text-transform-upperlower-005.html text-transform/text-transform-upperlower-007.html text-transform/text-transform-upperlower-009.html text-transform/text-transform-upperlower-011.html text-transform/text-transform-upperlower-015.html text-transform/text-transform-upperlower-017.html text-transform/text-transform-upperlower-019.html text-transform/text-transform-upperlower-021.html text-transform/text-transform-upperlower-023.html text-transform/text-transform-upperlower-025.html text-transform/text-transform-upperlower-027.html text-transform/text-transform-upperlower-029.html text-transform/text-transform-upperlower-031.html text-transform/text-transform-upperlower-044.html text-transform/text-transform-upperlower-101.html text-transform/text-transform-upperlower-103.html text-transform-003.xht text-transform-bicameral-001.xht text-transform-bicameral-003.xht text-transform-bicameral-005.xht text-transform-bicameral-007.xht text-transform-bicameral-009.xht text-transform-bicameral-011.xht text-transform-bicameral-013.xht text-transform-bicameral-015.xht text-transform-bicameral-017.xht text-transform-bicameral-019.xht text-transform-bicameral-021.xht text-transform-unicase-001.xht text-transform-uppercase-001.xht text-transform-uppercase-002.xht

lowercase

Puts all letters in lowercase. text-transform/text-transform-lowercase-101.xht text-transform/text-transform-lowercase-102.xht text-transform/text-transform-upperlower-002.html text-transform/text-transform-upperlower-004.html text-transform/text-transform-upperlower-006.html text-transform/text-transform-upperlower-008.html text-transform/text-transform-upperlower-010.html text-transform/text-transform-upperlower-012.html text-transform/text-transform-upperlower-014.html text-transform/text-transform-upperlower-016.html text-transform/text-transform-upperlower-018.html text-transform/text-transform-upperlower-020.html text-transform/text-transform-upperlower-022.html text-transform/text-transform-upperlower-024.html text-transform/text-transform-upperlower-026.html text-transform/text-transform-upperlower-028.html text-transform/text-transform-upperlower-030.html text-transform/text-transform-upperlower-102.html text-transform/text-transform-upperlower-104.html text-transform-002.xht text-transform-bicameral-002.xht text-transform-bicameral-004.xht text-transform-bicameral-006.xht text-transform-bicameral-008.xht text-transform-bicameral-010.xht text-transform-bicameral-012.xht text-transform-bicameral-014.xht text-transform-bicameral-016.xht text-transform-bicameral-018.xht text-transform-bicameral-020.xht text-transform-bicameral-022.xht text-transform-lowercase-001.xht

full-width

Puts all typographic character units in fullwidth form. If a character does not have a corresponding fullwidth form, it is left as is. This value is typically used to typeset Latin letters and digits as if they were ideographic characters. text-transform/text-transform-fullwidth-001.xht text-transform/text-transform-fullwidth-002.xht text-transform/text-transform-fullwidth-004.xht text-transform/text-transform-fullwidth-005.xht

full-size-kana

Converts all [=small Kana=] characters to the equivalent [=full-size Kana=]. This value is typically used for ruby annotation text, where authors may want all small Kana to be drawn as large Kana to compensate for legibility issues at the small font sizes typically used in ruby. text-transform/text-transform-full-size-kana-001.html text-transform/text-transform-full-size-kana-002.html text-transform/text-transform-full-size-kana-003.html text-transform/text-transform-full-size-kana-004.html text-transform/text-transform-full-size-kana-005.html text-transform/text-transform-full-size-kana-006.html text-transform/text-transform-full-size-kana-007.html

abbr:lang(ja) { text-transform: full-width; }

        section > p:first-of-type::first-line {
          text-transform: uppercase;
        }
      

        rt { font-size: 50%; text-transform: full-size-kana; }
        :is(h1, h2, h3, h4) rt { text-transform: none; /* unset for large text*/ }
      

Mapping Rules

For ''capitalize'', what constitutes a “word“ is UA-dependent; [[!UAX29]] is suggested (but not required) for determining such word boundaries. Authors should not expect ''capitalize'' to follow language-specific titlecasing conventions (such as skipping articles in English). Out-of-flow elements and inline element boundaries must not introduce a 'text-transform' word boundary and must be ignored when determining such word boundaries. text-transform/text-transform-capitalize-033.html

The UA must use the full case mappings for Unicode characters, including any conditional casing rules, as defined in Default Case Algorithm section of The Unicode Standard [[!UNICODE]]. If (and only if) the content language of the element is, according to the rules of the document language, known, then any appropriate language-specific rules must be applied as well. These minimally include, but are not limited to, the language-specific rules in Unicode's SpecialCasing.txt. writing-system/writing-system-text-transform-001.html text-transform/text-transform-tailoring-001.html text-transform/text-transform-tailoring-002.html text-transform/text-transform-tailoring-002a.html text-transform/text-transform-tailoring-003.html text-transform/text-transform-tailoring-004.html text-transform/text-transform-tailoring-005.html text-transform/text-transform-upperlower-032.html text-transform/text-transform-upperlower-033.html text-transform/text-transform-upperlower-034.html text-transform/text-transform-upperlower-035.html text-transform/text-transform-upperlower-038.html text-transform/text-transform-upperlower-039.html text-transform/text-transform-upperlower-040.html text-transform/text-transform-upperlower-041.html text-transform/text-transform-upperlower-042.html text-transform/text-transform-upperlower-043.html

The definition of fullwidth and halfwidth forms can be found on the Unicode consortium web site at [[!UAX11]]. The mapping to fullwidth form is defined by taking code points with the <wide> or the <narrow> tag in their Decomposition_Mapping in [[!UAX44]]. For the <narrow> tag, the mapping is from the code point to the decomposition (minus <narrow> tag), and for the <wide> tag, the mapping is from the decomposition (minus the <wide> tag) back to the original code point. text-transform/text-transform-fullwidth-001.xht text-transform/text-transform-fullwidth-002.xht text-transform/text-transform-fullwidth-004.xht text-transform/text-transform-fullwidth-005.xht text-transform/text-transform-fullwidth-006.html text-transform/text-transform-fullwidth-007.html

The mappings for small Kana to full-size Kana are defined in [[#small-kana]].

Order of Operations

When multiple values are specified and therefore multiple transformations need to be applied, they are applied in the following order:

1. ''capitalize'', ''uppercase'', and ''lowercase''
2. ''full-width''
3. ''full-size-kana''

Text transformation happens after [[#white-space-phase-1]] but before [[#white-space-phase-2]]. This means that ''full-width'' only transforms U+0020 spaces to U+3000 within preserved [=white space=]. text-transform/text-transform-fullwidth-006.html text-transform/text-transform-fullwidth-007.html text-transform/text-transform-fullwidth-008.html text-transform/text-transform-fullwidth-009.html

Note: As defined in Text Processing Order of Operations, transforming text affects line-breaking and other formatting operations.

White Space and Wrapping: the 'white-space' property

  Name: white-space
  Value: normal | pre | nowrap | pre-wrap | break-spaces | pre-line
  Initial: normal
  Applies to: inline boxes
  Inherited: yes
  Canonical order: n/a
  Computed value: specified keyword
  Animation type: discrete
  

This property specifies two things:

• whether and how white space inside the element is collapsed
• whether lines may wrap at unforced soft wrap opportunities

Values have the following meanings, which must be interpreted according to the White Space Processing and Line Breaking rules:

normal

This value directs user agents to collapse sequences of white space into a single character (or in some cases, no character). Lines may wrap at allowed soft wrap opportunities, as determined by the line-breaking rules in effect, in order to minimize inline-axis overflow. white-space/white-space-normal-011.html white-space/white-space-pre-031.html white-space/white-space-wrap-after-nowrap-001.html line-break/line-break-anywhere-and-white-space-004.html line-break/line-break-anywhere-and-white-space-005.html white-space-normal-001.xht white-space-normal-002.xht white-space-normal-003.xht white-space-normal-004.xht white-space-normal-005.xht white-space-normal-006.xht white-space-normal-007.xht white-space-normal-008.xht white-space-normal-009.xht white-space-p-element-001.xht

pre

This value prevents user agents from collapsing sequences of white space. Segment breaks such as line feeds are preserved as forced line breaks. Lines only break at forced line breaks; content that does not fit within the block container overflows it. white-space-pre-001.xht white-space-pre-002.xht white-space-pre-005.xht white-space-pre-006.xht white-space-pre-element-001.xht white-space/white-space-pre-031.html white-space/white-space-pre-032.html white-space/white-space-pre-034.html white-space/white-space-pre-035.html white-space/white-space-pre-011.html white-space/white-space-pre-051.html white-space/white-space-pre-052.html line-break/line-break-anywhere-and-white-space-001.html line-break/line-break-anywhere-and-white-space-003.html white-space/white-space-zero-fontsize-001.html white-space/white-space-zero-fontsize-002.html white-space/white-space-intrinsic-size-015.html white-space/white-space-intrinsic-size-016.html white-space/white-space-intrinsic-size-018.html

nowrap

Like ''white-space/normal'', this value collapses white space; but like ''pre'', it does not allow wrapping. white-space/white-space-nowrap-011.html white-space/white-space-wrap-after-nowrap-001.html line-break/line-break-anywhere-and-white-space-002.html overflow-wrap/overflow-wrap-anywhere-008.html white-space-nowrap-001.xht white-space-nowrap-005.xht white-space-nowrap-006.xht text-align-white-space-004.xht text-align-white-space-008.xht white-space-nowrap-attribute-001.xht white-space-processing-006.xht

pre-wrap

Like ''pre'', this value preserves white space; but like ''white-space/normal'', it allows wrapping. white-space/pre-wrap-001.html white-space/pre-wrap-002.html white-space/pre-wrap-003.html white-space/pre-wrap-004.html white-space/pre-wrap-005.html white-space/pre-wrap-006.html white-space/pre-wrap-007.html white-space/pre-wrap-009.html white-space/pre-wrap-010.html white-space/pre-wrap-011.html white-space/pre-wrap-012.html white-space/pre-wrap-013.html white-space/pre-wrap-014.html white-space/pre-wrap-051.html white-space/pre-wrap-052.html white-space/textarea-pre-wrap-001.html white-space/textarea-pre-wrap-002.html white-space/textarea-pre-wrap-003.html white-space/textarea-pre-wrap-004.html white-space/textarea-pre-wrap-005.html white-space/textarea-pre-wrap-006.html white-space/textarea-pre-wrap-007.html white-space/textarea-pre-wrap-011.html white-space/textarea-pre-wrap-012.html white-space/textarea-pre-wrap-013.html white-space/textarea-pre-wrap-014.html white-space/white-space-pre-032.html white-space/pre-wrap-leading-spaces-001.html white-space/pre-wrap-leading-spaces-002.html white-space/pre-wrap-leading-spaces-003.html white-space/pre-wrap-leading-spaces-004.html white-space/pre-wrap-leading-spaces-005.html white-space/pre-wrap-leading-spaces-006.html white-space/pre-wrap-leading-spaces-007.html white-space/pre-wrap-leading-spaces-008.html white-space/pre-wrap-leading-spaces-009.html white-space/pre-wrap-leading-spaces-010.html white-space/pre-wrap-leading-spaces-011.html white-space/pre-wrap-leading-spaces-012.html white-space/pre-wrap-leading-spaces-013.html white-space/pre-wrap-leading-spaces-014.html white-space/white-space-pre-wrap-trailing-spaces-001.html white-space/white-space-pre-wrap-trailing-spaces-002.html white-space/white-space-pre-wrap-trailing-spaces-003.html white-space/white-space-pre-wrap-trailing-spaces-004.html white-space/white-space-pre-wrap-trailing-spaces-005.html white-space/white-space-pre-wrap-trailing-spaces-006.html white-space/white-space-pre-wrap-trailing-spaces-007.html white-space/white-space-pre-wrap-trailing-spaces-008.html white-space/white-space-pre-wrap-trailing-spaces-010.html white-space/white-space-pre-wrap-trailing-spaces-011.html white-space/trailing-other-space-separators-002.html white-space/pre-wrap-tab-001.html white-space/pre-wrap-tab-002.html white-space/pre-wrap-tab-003.html white-space/pre-wrap-tab-004.html white-space/pre-wrap-tab-005.html white-space/pre-wrap-tab-006.html line-break/line-break-anywhere-and-white-space-006.html line-break/line-break-anywhere-and-white-space-007.html white-space/white-space-intrinsic-size-013.html white-space/white-space-intrinsic-size-014.html white-space/white-space-intrinsic-size-017.html

break-spaces

The behavior is identical to that of ''white-space/pre-wrap'', except that: * Any sequence of preserved [=white space=] or [=other space separators=] always takes up space, including at the end of the line. * A line breaking opportunity exists after every preserved white space character and after every [=other space separator=] (including between adjacent spaces). overflow-wrap/overflow-wrap-break-word-002.html overflow-wrap/overflow-wrap-anywhere-002.html white-space/break-spaces-001.html white-space/break-spaces-002.html white-space/break-spaces-003.html white-space/break-spaces-004.html white-space/break-spaces-005.html white-space/break-spaces-006.html white-space/break-spaces-007.html white-space/break-spaces-008.html white-space/break-spaces-009.html white-space/break-spaces-010.html white-space/break-spaces-051.html white-space/break-spaces-052.html white-space/white-space-pre-034.html white-space/textarea-break-spaces-001.html white-space/textarea-break-spaces-002.html white-space/break-spaces-before-first-char-001.html white-space/break-spaces-before-first-char-002.html white-space/break-spaces-before-first-char-003.html white-space/break-spaces-before-first-char-004.html white-space/break-spaces-before-first-char-005.html white-space/break-spaces-before-first-char-006.html white-space/break-spaces-before-first-char-007.html white-space/break-spaces-before-first-char-008.html white-space/break-spaces-before-first-char-009.html white-space/break-spaces-before-first-char-010.html white-space/break-spaces-before-first-char-011.html white-space/break-spaces-before-first-char-012.html white-space/break-spaces-before-first-char-013.html white-space/break-spaces-before-first-char-014.html white-space/break-spaces-before-first-char-015.html white-space/break-spaces-before-first-char-016.html white-space/break-spaces-before-first-char-017.html white-space/break-spaces-before-first-char-018.html white-space/tab-stop-threshold-005.html white-space/tab-stop-threshold-006.html word-break/word-break-break-all-017.html white-space/break-spaces-tab-001.html white-space/break-spaces-tab-002.html white-space/break-spaces-tab-003.html white-space/break-spaces-tab-004.html white-space/break-spaces-tab-005.html white-space/break-spaces-tab-006.html white-space/break-spaces-with-overflow-wrap-001.html white-space/break-spaces-with-overflow-wrap-002.html white-space/break-spaces-with-overflow-wrap-003.html white-space/break-spaces-with-overflow-wrap-004.html white-space/break-spaces-with-overflow-wrap-005.html white-space/break-spaces-with-overflow-wrap-006.html white-space/break-spaces-with-overflow-wrap-007.html white-space/break-spaces-with-overflow-wrap-008.html white-space/break-spaces-with-overflow-wrap-009.html white-space/break-spaces-with-overflow-wrap-010.html line-break/line-break-anywhere-and-white-space-008.html line-break/line-break-anywhere-and-white-space-009.html white-space/ws-break-spaces-applies-to-001.html white-space/ws-break-spaces-applies-to-002.html white-space/ws-break-spaces-applies-to-003.html white-space/ws-break-spaces-applies-to-005.html white-space/ws-break-spaces-applies-to-006.html white-space/ws-break-spaces-applies-to-007.html white-space/ws-break-spaces-applies-to-008.html white-space/ws-break-spaces-applies-to-009.html white-space/ws-break-spaces-applies-to-010.html white-space/ws-break-spaces-applies-to-011.html white-space/ws-break-spaces-applies-to-012.html white-space/ws-break-spaces-applies-to-013.html white-space/ws-break-spaces-applies-to-014.html white-space/ws-break-spaces-applies-to-015.html white-space/break-spaces-newline-011.html white-space/break-spaces-newline-012.html white-space/break-spaces-newline-013.html white-space/break-spaces-newline-014.html white-space/break-spaces-newline-015.html white-space/break-spaces-newline-016.html Such [=preserved=] [=white space characters=] and [=other space separators=] take up space and do not [=hang=], and thus affect the box's intrinsic sizes ([=min-content size=] and [=max-content size=]). white-space/white-space-intrinsic-size-001.html white-space/white-space-intrinsic-size-002.html

Note: This value does not guarantee that there will never be any overflow due to white space: for example, if the line length is so short that even a single white space character does not fit, overflow is unavoidable.

pre-line

Like ''white-space/normal'', this value collapses consecutive [=white space characters=] and allows wrapping, but preserves segment breaks in the source as forced line breaks. white-space-005.xht white-space-generated-content-before-001.xht white-space-processing-004.xht white-space-processing-007.xht white-space-processing-010.xht white-space-processing-017.xht white-space-processing-021.xht white-space-processing-024.xht white-space-processing-027.xht white-space-processing-028.xht white-space-processing-029.xht white-space-processing-030.xht white-space-processing-035.xht white-space-processing-036.xht white-space-processing-045.xht white-space-processing-053.xht text-align-white-space-002.xht text-align-white-space-006.xht white-space/pre-line-051.html white-space/pre-line-052.html white-space/white-space-pre-035.html white-space/white-space-intrinsic-size-019.html white-space/white-space-intrinsic-size-020.html

[=White space=] that was not removed or collapsed due to white space processing is called preserved white space. Note: In some cases, [=preserved white space=] and [=other space separators=] can hang when at the end of the line; this can affect whether they are measured for [=intrinsic sizing=].

The following informative table summarizes the behavior of various 'white-space' values:

See White Space Processing Rules for details on how [=white space=] collapses. An informative summary of collapsing (''white-space/normal'' and ''nowrap'') is presented below:

• A sequence of segment breaks and other white space between two Chinese, Japanese, or Yi characters collapses into nothing.
• A zero width space before or after a [=white space=] sequence containing a segment break causes the entire sequence of white space to collapse into a zero width space.
• Otherwise, consecutive white space collapses into a single [=space=].

See Line Breaking for details on wrapping behavior.

White Space Processing Details

The source text of a document often contains formatting that is not relevant to the final rendering: for example, breaking the source into segments (lines) for ease of editing or adding [=white space characters=] such as [=tabs=] and [=spaces=] to indent the source code. CSS white space processing allows the author to control interpretation of such formatting: to preserve or collapse it away when rendering the document. White space processing in CSS interprets [=white space characters=] only for rendering: it has no effect on the underlying document data.

White space processing in CSS is controlled with the 'white-space' property.

CSS does not define document segmentation rules. Segments can be separated by a particular newline sequence (such as a line feed or CRLF pair), or delimited by some other mechanism, such as the SGML RECORD-START and RECORD-END tokens. For CSS processing, each document language–defined segment break and each line feed (U+000A) in the text is treated as a segment break, which is then interpreted for rendering as specified by the 'white-space' property. white-space-processing-005.xht white-space-processing-006.xht white-space-processing-007.xht

Note: A document parser might not only normalize any segment breaks, but also collapse other space characters or otherwise process white space according to markup rules. Because CSS processing occurs after the parsing stage, it is not possible to restore these characters for styling. Therefore, some of the behavior specified below can be affected by these limitations and may be user agent dependent.

Note: Anonymous blocks consisting entirely of collapsible white space are removed from the rendering tree. Thus any such white space surrounding a block-level element is collapsed away. See [[CSS2]] section 9.2.2.1

Control characters (Unicode category Cc)-- other than tabs (U+0009), line feeds (U+000A), carriage returns (U+000D) and sequences that form a segment break-- must be rendered as a visible glyph which the UA must synthethize if the glyphs found in the font are not visible, and must be otherwise treated as any other character of the Other Symbols (So) general category and Common script. The UA may use a glyph provided by a font specifically for the control character, substitute the glyphs provided for the corresponding symbol in the Control Pictures block, generate a visual representation of its code point value, or use some other method to provide an appropriate visible glyph. As required by [[!UNICODE]], unsupported Default_ignorable characters must be ignored for text rendering. white-space/control-chars-000.html white-space/control-chars-001.html white-space/control-chars-002.html white-space/control-chars-003.html white-space/control-chars-004.html white-space/control-chars-005.html white-space/control-chars-006.html white-space/control-chars-007.html white-space/control-chars-008.html white-space/control-chars-00B.html white-space/control-chars-00C.html white-space/control-chars-00D.html white-space/control-chars-00E.html white-space/control-chars-00F.html white-space/control-chars-010.html white-space/control-chars-011.html white-space/control-chars-012.html white-space/control-chars-013.html white-space/control-chars-014.html white-space/control-chars-015.html white-space/control-chars-016.html white-space/control-chars-017.html white-space/control-chars-018.html white-space/control-chars-019.html white-space/control-chars-01A.html white-space/control-chars-01B.html white-space/control-chars-01C.html white-space/control-chars-01D.html white-space/control-chars-01E.html white-space/control-chars-01F.html white-space/control-chars-07F.html white-space/control-chars-080.html white-space/control-chars-081.html white-space/control-chars-082.html white-space/control-chars-083.html white-space/control-chars-084.html white-space/control-chars-085.html white-space/control-chars-086.html white-space/control-chars-087.html white-space/control-chars-088.html white-space/control-chars-089.html white-space/control-chars-08A.html white-space/control-chars-08B.html white-space/control-chars-08C.html white-space/control-chars-08D.html white-space/control-chars-08E.html white-space/control-chars-08F.html white-space/control-chars-090.html white-space/control-chars-091.html white-space/control-chars-092.html white-space/control-chars-093.html white-space/control-chars-094.html white-space/control-chars-095.html white-space/control-chars-096.html white-space/control-chars-097.html white-space/control-chars-098.html white-space/control-chars-099.html white-space/control-chars-09A.html white-space/control-chars-09B.html white-space/control-chars-09C.html white-space/control-chars-09D.html white-space/control-chars-09E.html white-space/control-chars-09F.html Carriage returns (U+000D) are treated identically to spaces (U+0020) in all respects. white-space/control-chars-00D.html white-space-processing-005.xht white-space-processing-006.xht white-space-processing-007.xht Note: For HTML documents, carriage returns present in the source code are converted to line feeds at the parsing stage (see [[HTML#preprocessing-the-input-stream]] and the definition of [=normalize newlines=] in [[INFRA]]) and therefore do no appear as U+000D to CSS. However, the character is preserved-- and the above rule observable-- when encoded using an escape sequence (
).

The White Space Processing Rules

Except where specified otherwise, White space processing in CSS affects only the document white space characters: spaces (U+0020), tabs (U+0009), and segment breaks. white-space-normal-003.xht white-space-normal-004.xht white-space-normal-005.xht white-space-normal-006.xht white-space-normal-007.xht white-space-normal-008.xht white-space-nowrap-005.xht white-space-nowrap-006.xht white-space-pre-005.xht white-space-pre-006.xht white-space-processing-054.xht white-space-processing-055.xht white-space-processing-056.xht

Note: The set of characters considered document white space (part of the document content) and those considered syntactic white space (part of the CSS syntax) are not necessarily identical. However, since both include spaces (U+0020), tabs (U+0009), and line feeds (U+000A) most authors won't notice any differences.

Besides Space (U+0020) and No-Break Space (U+00A0), Unicode [[UNICODE]] defines a number of additional space separator characters. In this specification all characters in the Unicode Zs category (See [[!UAX44]]) except Space (U+0020) and No-Break Space (U+00A0) are collectively referred to as other space separators. white-space/trailing-other-space-separators-001.html white-space/trailing-other-space-separators-002.html white-space/trailing-other-space-separators-003.html white-space/trailing-other-space-separators-004.html white-space/trailing-other-space-separators-break-spaces-001.html white-space/trailing-other-space-separators-break-spaces-002.html white-space/trailing-other-space-separators-break-spaces-003.html white-space/trailing-other-space-separators-break-spaces-004.html white-space/trailing-other-space-separators-break-spaces-005.html white-space/trailing-other-space-separators-break-spaces-006.html white-space/trailing-other-space-separators-break-spaces-007.html white-space/trailing-other-space-separators-break-spaces-008.html white-space/trailing-other-space-separators-break-spaces-009.html white-space/trailing-other-space-separators-break-spaces-010.html white-space/trailing-other-space-separators-break-spaces-011.html white-space/trailing-other-space-separators-break-spaces-012.html white-space/trailing-other-space-separators-break-spaces-013.html white-space/trailing-other-space-separators-break-spaces-014.html white-space/trailing-other-space-separators-break-spaces-015.html

Phase I: Collapsing and Transformation

For each inline (including anonymous inlines; see [[CSS2]] section 9.2.2.1) within an [=inline formatting context=], [=white space characters=] are processed as follows prior to [=line breaking=] and bidi reordering, ignoring bidi formatting characters (characters with the Bidi_Control property [[!UAX9]]) as if they were not there: white-space/white-space-collapse-002.html white-space/white-space-normal-011.html white-space/white-space-nowrap-011.html

• If 'white-space' is set to ''white-space/normal'', ''nowrap'', or ''pre-line'', [=white space characters=] are considered collapsible and are processed by performing the following steps:

  1. Any sequence of collapsible [=spaces=] and [=tabs=] immediately preceding or following a segment break is removed. white-space/seg-break-transformation-000.html white-space/white-space-normal-011.html white-space/white-space-nowrap-011.html white-space-processing-002.xht white-space-processing-003.xht white-space-processing-004.xht white-space-processing-008.xht white-space-processing-009.xht white-space-processing-010.xht white-space-processing-005.xht white-space-processing-006.xht white-space-processing-007.xht
  2. Collapsible segment breaks are transformed for rendering according to the segment break transformation rules.
  3. Every [=collapsible=] [=tab=] is converted to a collapsible space (U+0020). white-space/white-space-collapse-000.html white-space/white-space-normal-011.html white-space/white-space-nowrap-011.html white-space-processing-019.xht white-space-processing-020.xht white-space-processing-021.xht
  4. Any [=collapsible=] [=space=] immediately following another [=collapsible=] [=space=]—even one outside the boundary of the inline containing that [=space=], provided both [=spaces=] are within the same inline formatting context—is collapsed to have zero advance width. (It is invisible, but retains its soft wrap opportunity, if any.) white-space/white-space-collapse-001.html white-space/white-space-empty-text-sibling.html white-space/white-space-normal-011.html white-space/white-space-nowrap-011.html white-space-001.xht white-space-003.xht white-space-005.xht white-space-collapsing-001.xht white-space-collapsing-002.xht white-space-collapsing-004.xht white-space-collapsing-005.xht white-space-collapsing-breaks-001.xht white-space-mixed-001.xht white-space-mixed-002.xht white-space-normal-001.xht white-space-processing-001.xht white-space-processing-022.xht white-space-processing-023.xht white-space-processing-024.xht white-space-processing-025.xht white-space-processing-026.xht white-space-processing-027.xht white-space-processing-028.xht white-space-processing-029.xht white-space-processing-030.xht white-space-processing-031.xht white-space-processing-032.xht white-space-processing-033.xht white-space-processing-034.xht white-space-processing-035.xht white-space-processing-036.xht white-space-processing-050.xht white-space-processing-051.xht white-space-processing-053.xht

• If 'white-space' is set to ''pre'', ''pre-wrap'', or ''break-spaces'', any sequence of spaces is treated as a sequence of non-breaking spaces. However, for ''pre-wrap'', a soft wrap opportunity exists at the end of a sequence of [=spaces=] and/or [=tabs=], while for ''break-spaces'', a soft wrap opportunity exists after every [=space=] and every [=tab=]. white-space/white-space-pre-011.html overflow-wrap/overflow-wrap-break-word-004.html overflow-wrap/overflow-wrap-break-word-005.html overflow-wrap/overflow-wrap-break-word-006.html overflow-wrap/overflow-wrap-break-word-007.html overflow-wrap/overflow-wrap-anywhere-004.html overflow-wrap/overflow-wrap-anywhere-005.html word-break/word-break-break-all-011.html word-break/word-break-break-all-012.html word-break/word-break-break-all-013.html word-break/word-break-break-all-015.html white-space/break-spaces-006.html white-space/break-spaces-007.html white-space/break-spaces-008.html white-space/break-spaces-009.html white-space/break-spaces-010.html white-space/break-spaces-before-first-char-001.html white-space/break-spaces-before-first-char-002.html white-space/break-spaces-before-first-char-003.html white-space/break-spaces-before-first-char-004.html white-space/break-spaces-before-first-char-005.html white-space/break-spaces-before-first-char-006.html white-space/break-spaces-before-first-char-011.html white-space/pre-wrap-008.html white-space/pre-wrap-015.html white-space/pre-wrap-016.html white-space/pre-wrap-leading-spaces-001.html white-space/pre-wrap-leading-spaces-002.html white-space/pre-wrap-leading-spaces-003.html white-space/pre-wrap-leading-spaces-004.html white-space/pre-wrap-leading-spaces-005.html white-space/pre-wrap-leading-spaces-006.html white-space/pre-wrap-leading-spaces-007.html white-space/pre-wrap-leading-spaces-008.html white-space/pre-wrap-leading-spaces-009.html white-space/pre-wrap-leading-spaces-010.html white-space/pre-wrap-leading-spaces-011.html white-space/pre-wrap-leading-spaces-012.html white-space/pre-wrap-leading-spaces-013.html white-space/pre-wrap-leading-spaces-014.html white-space/break-spaces-tab-001.html white-space/break-spaces-tab-002.html white-space/break-spaces-tab-003.html white-space/break-spaces-tab-004.html white-space/pre-wrap-tab-001.html white-space/pre-wrap-tab-002.html white-space/pre-wrap-tab-003.html white-space/pre-wrap-tab-004.html white-space-002.xht white-space-004.xht white-space-processing-011.xht white-space-processing-012.xht white-space-processing-013.xht white-space-processing-052.xht

<ltr>A <rtl> B </rtl> C</ltr>

A  BC

Phase II: Trimming and Positioning

Then, the entire block is rendered. Inlines are laid out, taking bidi reordering into account, and wrapping as specified by the 'white-space' property. As each line is laid out,

1. A sequence of [=collapsible=] [=spaces=] at the beginning of a line is removed. white-space/line-edge-white-space-collapse-002.html white-space/break-spaces-051.html white-space/break-spaces-052.html white-space/pre-line-051.html white-space/pre-line-052.html white-space/pre-wrap-051.html white-space/pre-wrap-052.html white-space/white-space-pre-051.html white-space/white-space-pre-052.html white-space-collapsing-003.xht white-space-collapsing-bidi-003.xht white-space-normal-001.xht white-space-normal-002.xht white-space-processing-037.xht white-space-processing-038.xht white-space-processing-039.xht white-space-processing-040.xht white-space-processing-041.xht
2. If the [=tab size=] is zero, [=preserved=] [=tabs=] are not rendered. Otherwise, each [=preserved=] [=tab=] is rendered as a horizontal shift that lines up the start edge of the next glyph with the next tab stop. If this distance is less than 0.5ch, then the subsequent tab stop is used instead. Tab stops occur at points that are multiples of the [=tab size=] from the starting content edge of the [=preserved=] [=tab=]'s nearest [=block container=] ancestor. The [=tab size=] is given by the 'tab-size' property. white-space/tab-stop-threshold-001.html white-space/tab-stop-threshold-002.html white-space/tab-stop-threshold-003.html white-space/tab-stop-threshold-004.html white-space/tab-stop-threshold-005.html white-space/tab-stop-threshold-006.html white-space/white-space-pre-011.html tab-size/tab-min-rendered-width-1.html tab-size/tab-size-integer-003.html text-indent/text-indent-tab-positions-001.html tab-size/tab-size-inline-002.html white-space-processing-042.xht Note: See [[UAX9]] for rules on how U+0009 tabulation interacts with bidi.
3. A sequence at the end of a line of collapsible [=spaces=] is removed, as well as any trailing U+1680 OGHAM SPACE MARK whose 'white-space' property is ''white-space/normal'', ''nowrap'', or ''pre-line''. white-space/line-edge-white-space-collapse-001.html white-space/pre-float-001.html white-space/pre-wrap-float-001.html white-space/trailing-space-before-br-001.html white-space/trailing-ogham-001.html white-space/trailing-ogham-002.html white-space/trailing-ogham-003.html white-space-collapsing-003.xht white-space-collapsing-bidi-003.xht white-space-normal-001.xht white-space-normal-002.xht white-space-processing-005.xht white-space-processing-043.xht white-space-processing-044.xht white-space-processing-045.xht white-space-processing-046.xht white-space-processing-047.xht In the case of bidirectional text, any sequence of [=collapsible=] [=spaces=] located at the end of the line prior to bidi reordering [[CSS-WRITING-MODES-3]] is also removed, and bidi reordering is applied on the remaining content of the line. white-space/eol-spaces-bidi-001.html white-space/trailing-space-rtl-001.html
4. If there remains any sequence of white space, and/or [=other space separators=], at the end of a line (after bidi reordering [[CSS-WRITING-MODES-3]]):
   • If 'white-space' is set to ''white-space/normal'', ''white-space/nowrap'', or ''white-space/pre-line'', the UA must [=hang=] this sequence (unconditionally). white-space/trailing-ideographic-space-001.html white-space/trailing-ideographic-space-002.html white-space/trailing-other-space-separators-001.html white-space/trailing-other-space-separators-003.html white-space/trailing-other-space-separators-004.html text-transform/text-transform-fullwidth-008.html white-space/white-space-intrinsic-size-019.html white-space/white-space-intrinsic-size-020.html
   • If 'white-space' is set to ''pre-wrap'', the UA must (unconditionally) [=hang=] this sequence, unless the sequence is followed by a [=forced line break=], in which case it must [=conditionally hang=] the sequence is instead. It may also visually collapse the character advance widths of any that would otherwise overflow. white-space/pre-wrap-001.html white-space/pre-wrap-002.html white-space/pre-wrap-003.html white-space/pre-wrap-004.html white-space/pre-wrap-005.html white-space/pre-wrap-006.html white-space/pre-wrap-007.html white-space/pre-wrap-011.html white-space/pre-wrap-012.html white-space/pre-wrap-013.html white-space/pre-wrap-014.html white-space/pre-wrap-017.html white-space/pre-wrap-018.html white-space/pre-wrap-019.html white-space/pre-wrap-020.html white-space/textarea-pre-wrap-001.html white-space/textarea-pre-wrap-002.html white-space/textarea-pre-wrap-003.html white-space/textarea-pre-wrap-004.html white-space/textarea-pre-wrap-005.html white-space/textarea-pre-wrap-006.html white-space/textarea-pre-wrap-007.html white-space/textarea-pre-wrap-011.html white-space/textarea-pre-wrap-012.html white-space/textarea-pre-wrap-013.html white-space/textarea-pre-wrap-014.html white-space/trailing-ideographic-space-003.html white-space/trailing-ideographic-space-004.html white-space/white-space-pre-wrap-trailing-spaces-001.html white-space/white-space-pre-wrap-trailing-spaces-002.html white-space/white-space-pre-wrap-trailing-spaces-003.html white-space/white-space-pre-wrap-trailing-spaces-004.html white-space/white-space-pre-wrap-trailing-spaces-005.html white-space/white-space-pre-wrap-trailing-spaces-006.html white-space/white-space-pre-wrap-trailing-spaces-007.html white-space/white-space-pre-wrap-trailing-spaces-008.html white-space/white-space-pre-wrap-trailing-spaces-010.html white-space/white-space-pre-wrap-trailing-spaces-011.html white-space/white-space-pre-wrap-trailing-spaces-012.html white-space/white-space-pre-wrap-trailing-spaces-013.html white-space/white-space-pre-wrap-trailing-spaces-014.html white-space/white-space-pre-wrap-trailing-spaces-015.html white-space/white-space-intrinsic-size-003.html white-space/white-space-intrinsic-size-004.html white-space/pre-wrap-tab-005.html white-space/pre-wrap-tab-006.html white-space/trailing-other-space-separators-002.html text-transform/text-transform-fullwidth-009.html white-space/trailing-space-position-001.html line-break/line-break-anywhere-and-white-space-006.html line-break/line-break-anywhere-and-white-space-007.html white-space/white-space-intrinsic-size-013.html white-space/white-space-intrinsic-size-014.html white-space/white-space-intrinsic-size-017.html white-space/eol-spaces-bidi-002.html white-space/trailing-space-in-inline-box.html Note: [=Hanging=] the white space rather than collapsing it allows users to see the space when selecting or editing text.
   • If 'white-space' is set to ''break-spaces'', [=hanging=] or collapsing the advance width of the [=spaces=], [=tabs=], or [=other space separators=] at the end of the line is not allowed; those that overflow must wrap to the next line. white-space/break-spaces-001.html white-space/break-spaces-005.html white-space/textarea-break-spaces-001.html white-space/break-spaces-tab-005.html white-space/break-spaces-tab-006.html white-space/trailing-other-space-separators-break-spaces-001.html white-space/trailing-other-space-separators-break-spaces-002.html white-space/trailing-other-space-separators-break-spaces-003.html white-space/trailing-other-space-separators-break-spaces-004.html white-space/trailing-other-space-separators-break-spaces-005.html white-space/trailing-other-space-separators-break-spaces-006.html white-space/trailing-other-space-separators-break-spaces-007.html white-space/trailing-other-space-separators-break-spaces-008.html white-space/trailing-other-space-separators-break-spaces-009.html white-space/trailing-other-space-separators-break-spaces-010.html white-space/trailing-other-space-separators-break-spaces-011.html white-space/trailing-other-space-separators-break-spaces-012.html white-space/trailing-other-space-separators-break-spaces-013.html white-space/trailing-other-space-separators-break-spaces-014.html white-space/trailing-other-space-separators-break-spaces-015.html line-break/line-break-anywhere-and-white-space-008.html line-break/line-break-anywhere-and-white-space-009.html

      p {
        white-space: pre-wrap;
        width: 5ch;
        border: solid 1px;
        font-family: monospace;
        text-align: center;
      }

      <p> 0 </p>
      

      p {
        white-space: pre-wrap;
        width: 3ch;
        border: solid 1px;
        font-family: monospace;
      }

      <p> 0 0 0 0 </p>
      

      p {
        white-space: pre-wrap;
        width: 3ch;
        border: solid 1px;
        font-family: monospace;
      }

      <p>0 0 0 0 </p>
      

Segment Break Transformation Rules

When 'white-space' is ''pre'', ''pre-wrap'', ''break-spaces'', or ''pre-line'', segment breaks are not collapsible and are instead transformed into a preserved line feed (U+000A). white-space-008.xht white-space-processing-016.xht white-space-processing-017.xht white-space-processing-018.xht

For other values of 'white-space', segment breaks are collapsible. Any collapsible segment break immediately following another collapsible segment break is removed. Then any remaining segment break is either transformed into a space (U+0020) or removed depending on the context before and after the break: segment-break-transformation-removable-2.html segment-break-transformation-removable-4.html white-space/seg-break-transformation-000.html

• If the character immediately before or immediately after the [=segment break=] is the zero-width space character (U+200B), then the break is removed, leaving behind the zero-width space. white-space/seg-break-transformation-016.html white-space/seg-break-transformation-017.html white-space/seg-break-transformation-018.html white-space/seg-break-transformation-019.html segment-break-transformation-removable-1.html segment-break-transformation-removable-3.html
• Otherwise, if both the characters before and after the [=segment break=] belong to the [=space-discarding character set=] (see [[#space-discard-set]]), then the [=segment break=] is removed.
• Otherwise, the [=segment break=] is converted to a space (U+0020). white-space/seg-break-transformation-000.html white-space-processing-005.xht white-space-processing-014.xht white-space-processing-015.xht

            Here is an English paragraph
            that is broken into multiple lines
            in the source code so that it can
            more easily read in a text editor.
          

            這個段落是那麼長，
            在一行寫不行。最好
            用三行寫。
          

Comments on how well these rules would work in practice would be very much appreciated, particularly from people who work with Thai and similar scripts. Note that browser implementations do not currently follow these rules consistently (although IE does in some cases transform the break, and Firefox follows the first two bullet points).

Tab Character Size: the 'tab-size' property

    Name: tab-size
    Value: <> | <>
    Initial: 8
    Applies to: inline boxes
    Inherited: yes
    Computed value: the specified number or absolute length
    Animation type: by computed value type
    Canonical order: n/a
    

This property determines the tab size used to render [=preserved=] tab characters (U+0009). A <> represents the measure as a multiple of the advance width of the space character (U+0020) of the nearest [=block container=] ancestor of the [=preserved=] [=tab=], including its associated 'letter-spacing' and 'word-spacing'. Negative values are not allowed. tab-size/tab-size-integer-001.html tab-size/tab-size-integer-002.html tab-size/tab-size-integer-003.html tab-size/tab-size-integer-004.html tab-size/tab-size-length-001.html tab-size/tab-size-length-002.html tab-size/tab-size-percent-001.html tab-size/tab-min-rendered-width-1.html tab-size/tab-size-spacing-001.html white-space/tab-stop-threshold-001.html white-space/tab-stop-threshold-002.html white-space/tab-stop-threshold-003.html white-space/tab-stop-threshold-004.html white-space/tab-stop-threshold-005.html white-space/tab-stop-threshold-006.html text-indent/text-indent-tab-positions-001.html white-space-processing-042.xht

Line Breaking and Word Boundaries

When inline-level content is laid out into lines, it is broken across line boxes. Such a break is called a line break. When a line is broken due to explicit line-breaking controls (such as a preserved newline character), or due to the start or end of a block, it is a forced line break. When a line is broken due to content wrapping (i.e. when the UA creates unforced line breaks in order to fit the content within the measure), it is a soft wrap break. The process of breaking inline-level content into lines is called line breaking.

Wrapping is only performed at an allowed break point, called a soft wrap opportunity. When wrapping is enabled (see 'white-space'), the UA must minimize the amount of content overflowing a line by wrapping the line at a soft wrap opportunity, if one exists. line-breaking/line-breaking-020.html

In most writing systems, in the absence of hyphenation a soft wrap opportunity occurs only at word boundaries. Many such systems use [=spaces=] or punctuation to explicitly separate words, and soft wrap opportunities can be identified by these characters. Scripts such as Thai, Lao, and Khmer, however, do not use spaces or punctuation to separate words. Although the zero width space (U+200B) can be used as an explicit word delimiter in these scripts, this practice is not common. As a result, a lexical resource is needed to correctly identify soft wrap opportunities in such texts.

In some other writing systems, soft wrap opportunities are based on orthographic syllable boundaries, not word boundaries. Some of these systems, such as Javanese and Balinese, are similar to Thai and Lao in that they require analysis of the text to find breaking opportunities. In others such as Chinese (as well as Japanese, Yi, and sometimes also Korean), each syllable tends to correspond to a single typographic letter unit, and thus line breaking conventions allow the line to break anywhere except between certain character combinations. Additionally the level of strictness in these restrictions varies with the typesetting style. i18n/css3-text-line-break-baspglwj-003.html i18n/css3-text-line-break-baspglwj-004.html i18n/css3-text-line-break-baspglwj-005.html i18n/css3-text-line-break-baspglwj-006.html i18n/css3-text-line-break-baspglwj-007.html i18n/css3-text-line-break-baspglwj-008.html i18n/css3-text-line-break-baspglwj-009.html i18n/css3-text-line-break-baspglwj-010.html i18n/css3-text-line-break-baspglwj-011.html i18n/css3-text-line-break-baspglwj-012.html i18n/css3-text-line-break-baspglwj-014.html i18n/css3-text-line-break-baspglwj-015.html i18n/css3-text-line-break-baspglwj-016.html i18n/css3-text-line-break-baspglwj-017.html i18n/css3-text-line-break-baspglwj-018.html i18n/css3-text-line-break-baspglwj-019.html i18n/css3-text-line-break-baspglwj-020.html i18n/css3-text-line-break-baspglwj-021.html i18n/css3-text-line-break-baspglwj-022.html i18n/css3-text-line-break-baspglwj-023.html 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While CSS does not fully define where soft wrap opportunities occur, some controls are provided to distinguish common variations:

• The 'line-break' property allows choosing various levels of “strictness” for line breaking restrictions.
• The 'word-break' property controls what types of letters are glommed together to form unbreakable “words”, causing CJK characters to behave like non-CJK text or vice versa.
• The 'hyphens' property controls whether automatic hyphenation is allowed to break words in scripts that hyphenate.
• The 'overflow-wrap' property allows the UA to take a break anywhere in otherwise-unbreakable strings that would otherwise overflow.

Line Breaking Details

When determining line breaks:

• The interaction of [=line breaking=] and bidirectional text is defined by [[!CSS-WRITING-MODES-3]] and [[!UAX9]], see in particular [[css-writing-modes-3#bidi-algo]] and UAX9§3.4 Reordering Resolved Levels. bidi-breaking-001.xht bidi-breaking-002.xht bidi-breaking-003.xht
• Regardless of the 'white-space' value, lines always break at each preserved forced break character: thus for all values, line-breaking behavior defined for the BK and NL Unicode line breaking classes [[!UAX14]] must be honored. Note: The bidi implications of such [=forced line breaks=] are defined by [[!UAX9]].
• Except where explicitly defined otherwise (e.g. for ''line-break: anywhere'' or ''overflow-wrap: anywhere'') line breaking behavior defined for the WJ, ZW, GL, and ZWJ Unicode line breaking classes [[!UAX14]] must be honored. word-break/word-break-normal-001.html line-breaking/line-breaking-001.html line-breaking/line-breaking-002.html line-breaking/line-breaking-003.html line-breaking/line-breaking-004.html line-breaking/line-breaking-005.html line-breaking/line-breaking-006.html line-breaking/line-breaking-007.html line-breaking/line-breaking-008.html line-breaking/line-breaking-021.html i18n/css3-text-line-break-baspglwj-001.html i18n/css3-text-line-break-baspglwj-002.html i18n/css3-text-line-break-baspglwj-120.html i18n/css3-text-line-break-baspglwj-121.html i18n/css3-text-line-break-baspglwj-122.html i18n/css3-text-line-break-baspglwj-123.html i18n/css3-text-line-break-baspglwj-124.html i18n/css3-text-line-break-baspglwj-125.html i18n/css3-text-line-break-baspglwj-126.html i18n/css3-text-line-break-baspglwj-127.html i18n/css3-text-line-break-baspglwj-128.html i18n/css3-text-line-break-baspglwj-130.html i18n/css3-text-line-break-baspglwj-131.html word-break/word-break-break-all-018.html word-break/word-break-break-all-021.html word-break/word-break-break-all-022.html
• UAs that allow wrapping at punctuation other than word separators in writing systems that use them should prioritize breakpoints. (For example, if breaks after slashes are given a lower priority than spaces, the sequence “check /etc” will never break between the "/" and the "e".) As long as care is taken to avoid such awkward breaks, allowing breaks at appropriate punctuation other than word separators is recommended, as it results in more even-looking margins, particularly in narrow measures. The UA may use the width of the containing block, the text's language, the 'line-break' value, and other factors in assigning priorities: CSS does not define prioritization of line breaking opportunities. Prioritization of word separators is not expected, however, if ''word-break: break-all'' is specified (since this value explicitly requests line breaking behavior not based on breaking at word separators)-- and is forbidden under ''line-break: anywhere''.
• Out-of-flow elements and inline element boundaries do not introduce a forced line break or soft wrap opportunity in the flow. line-breaking/line-breaking-012.html line-breaking/line-breaking-015.html line-breaking/line-breaking-016.html line-breaking/line-breaking-017.html line-breaking/line-breaking-018.html line-breaking/line-breaking-019.html
• For Web-compatibility there is a [=soft wrap opportunity=] before and after each replaced element or other [=atomic inline=], even when adjacent to a character that would normally suppress them, such as U+00A0 NO-BREAK SPACE. line-breaking/line-breaking-atomic-001.html line-breaking/line-breaking-atomic-002.html line-breaking/line-breaking-atomic-003.html line-breaking/line-breaking-atomic-004.html line-breaking/line-breaking-atomic-005.html line-breaking/line-breaking-atomic-006.html line-breaking/line-breaking-atomic-007.html line-breaking/line-breaking-atomic-008.html line-breaking/line-breaking-atomic-009.html line-breaking/line-breaking-replaced-001.html line-breaking/line-breaking-replaced-002.html line-breaking/line-breaking-replaced-003.html line-breaking/line-breaking-replaced-004.html line-breaking/line-breaking-replaced-005.html line-breaking/line-breaking-replaced-006.html line-breaking/line-breaking-atomic-nowrap-001.html
• For soft wrap opportunities created by characters that disappear at the line break (e.g. U+0020 SPACE), properties on the box directly containing that character control the line breaking at that opportunity. For soft wrap opportunities defined by the boundary between two characters, the 'white-space' property on the nearest common ancestor of the two characters controls breaking; which elements’ 'line-break', 'word-break', and 'overflow-wrap' properties control the determination of [=soft wrap opportunities=] at such boundaries is undefined in Level 3. line-breaking/line-breaking-009.html line-breaking/line-breaking-010.html line-breaking/line-breaking-011.html line-breaking/line-breaking-ic-001.html line-breaking/line-breaking-ic-002.html line-breaking/line-breaking-ic-003.html white-space/white-space-wrap-after-nowrap-001.html word-break/word-break-break-all-inline-010.html overflow-wrap/overflow-wrap-anywhere-inline-003.html
• For soft wrap opportunities before the first or after the last character of a box, the break occurs immediately before/after the box (at its margin edge) rather than breaking the box between its content edge and the content.
• Line breaking in/around Ruby is defined in CSS Ruby [[!CSS-RUBY-1]].
• In order to avoid unexpected overflow, if the User Agent is unable to perform the requisite lexical or orthographic analysis for line breaking any [=content language=] that requires it-- for example due to lacking a dictionary for certain languages-- it must assume a [=soft wrap opportunity=] between pairs of [=typographic letter units=] in that writing system. Note: This provision is not triggered merely when the UA fails to find a word boundary in a particular text run; the text run may well be a single unbreakable word. It applies for example when a text run is composed of Khmer characters (U+1780 to U+17FF) if the User Agent does not know how to determine word boundaries in Khmer.

Breaking Rules for Letters: the 'word-break' property

    Name: word-break
    Value: normal | keep-all | break-all | break-word
    Initial: normal
    Applies to: inline boxes
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    

This property specifies soft wrap opportunities between letters, i.e. where it is “normal” and permissible to break lines of text. Specifically it controls whether a soft wrap opportunity generally exists between adjacent typographic letter units, treating non-letter typographic character units belonging to the NU, AL, AI, or ID Unicode line breaking classes [[!UAX14]] as typographic letter units for this purpose (only). It does not affect rules governing the soft wrap opportunities created by [=white space=] (as well as by [=other space separators=]) and around punctuation. (See 'line-break' for controls affecting punctuation and small kana.) word-break/word-break-break-all-010.html word-break/word-break-break-all-020.html word-break/word-break-keep-all-005.html word-break/word-break-keep-all-006.html word-break/word-break-keep-all-007.html word-break/word-break-keep-all-008.html word-break/word-break-break-all-012.html word-break/word-break-break-all-013.html word-break/word-break-break-all-015.html word-break/word-break-break-all-016.html word-break/word-break-break-all-019.html word-break/word-break-break-all-020.html word-break/word-break-break-all-023.html word-break/word-break-break-all-024.html word-break/word-break-break-all-025.html word-break/word-break-break-all-026.html word-break/word-break-break-all-027.html word-break/word-break-break-all-028.html word-break/word-break-break-all-inline-008.html white-space/break-spaces-008.html word-break/word-break-min-content-003.html

For example, in some styles of CJK typesetting, English words are allowed to break between any two letters, rather than only at spaces or hyphenation points; this can be enabled with ''word-break:break-all''.

An example of English text embedded in Japanese being broken at an arbitrary point in the word.

As another example, Korean has two styles of line-breaking: between any two Korean syllables (''word-break: normal'') or, like English, mainly at spaces (''word-break: keep-all'').

        각 줄의 마지막에 한글이 올 때 줄 나눔 기
        준을 “글자” 또는 “어절” 단위로 한다.

        각 줄의 마지막에 한글이 올 때 줄 나눔
        기준을 “글자” 또는 “어절” 단위로 한다.

Ethiopic similarly has two styles of line-breaking, either only breaking at [=word separators=] (''word-break: normal''), or also allowing breaks between letters within a word (''word-break: break-all'').

        ተወልዱ፡ኵሉ፡ሰብእ፡ግዑዛን፡ወዕሩያን፡
        በማዕረግ፡ወብሕግ።ቦሙ፡ኅሊና፡ወዐቅል፡
        ወይትጌበሩ፡አሐዱ፡ምስለ፡አሀዱ፡
        በመንፈሰ፡እኍና።
      

        ተወልዱ፡ኵሉ፡ሰብእ፡ግዑዛን፡ወዕሩያን፡በማ
        ዕረግ፡ወብሕግ።ቦሙ፡ኅሊና፡ወዐቅል፡ወይትጌ
        በሩ፡አሐዱ፡ምስለ፡አሀዱ፡በመንፈሰ፡እኍና።
      

Note: To enable additional break opportunities only in the case of overflow, see 'overflow-wrap'.

Values have the following meanings:

normal

Words break according to their customary rules, as described above. Korean, which commonly exhibits two different behaviors, allows breaks between any two consecutive Hangul/Hanja. For Ethiopic, which also exhibits two different behaviors, such breaks within words are not allowed. word-break/word-break-normal-ar-000.html word-break/word-break-normal-bo-000.html word-break/word-break-normal-en-000.html word-break/word-break-normal-hi-000.html word-break/word-break-normal-ja-000.html word-break/word-break-normal-ja-001.html word-break/word-break-normal-ja-002.html word-break/word-break-normal-ja-004.html word-break/word-break-normal-km-000.html word-break/word-break-normal-ko-000.html word-break/word-break-normal-lo-000.html word-break/word-break-normal-my-000.html word-break/word-break-normal-tdd-000.html word-break/word-break-normal-th-000.html word-break/word-break-normal-zh-000.html

break-all

Breaking is allowed within “words”: specifically, in addition to soft wrap opportunities allowed for ''word-break/normal'', any typographic letter units (and any typographic character units resolving to the NU (“numeric”), AL (“alphabetic”), or SA (“Southeast Asian”) line breaking classes [[!UAX14]]) are instead treated as ID (“ideographic characters”) for the purpose of line-breaking. Hyphenation is not applied. word-break/word-break-break-all-000.html word-break/word-break-break-all-001.html word-break/word-break-break-all-002.html word-break/word-break-break-all-003.html word-break/word-break-break-all-005.html word-break/word-break-break-all-006.html word-break/word-break-break-all-012.html word-break/word-break-break-all-013.html word-break/word-break-break-all-014.html word-break/word-break-break-all-015.html word-break/word-break-break-all-016.html word-break/word-break-break-all-017.html word-break/word-break-break-all-018.html word-break/word-break-break-all-019.html word-break/word-break-break-all-020.html word-break/word-break-break-all-021.html word-break/word-break-break-all-022.html word-break/word-break-break-all-023.html word-break/word-break-break-all-024.html word-break/word-break-break-all-025.html word-break/word-break-break-all-026.html word-break/word-break-break-all-027.html word-break/word-break-break-all-028.html word-break/word-break-break-all-029.html word-break/word-break-break-all-030.html word-break/word-break-break-all-inline-001.html word-break/word-break-break-all-inline-002.html word-break/word-break-break-all-inline-003.html word-break/word-break-break-all-inline-004.html word-break/word-break-break-all-inline-005.html word-break/word-break-break-all-inline-006.html word-break/word-break-break-all-inline-007.html word-break/word-break-break-all-inline-008.html word-break/word-break-break-all-inline-009.html word-break/word-break-break-all-inline-010.html white-space/break-spaces-006.html white-space/break-spaces-008.html white-space/break-spaces-before-first-char-004.html white-space/break-spaces-before-first-char-005.html white-space/break-spaces-before-first-char-006.html overflow-wrap/overflow-wrap-anywhere-006.html line-break/line-break-loose-hyphens-002.html line-break/line-break-normal-hyphens-002.html line-break/line-break-strict-hyphens-002.html Note: This value does not affect whether there are soft wrap opportunities around punctuation characters. To allow breaks anywhere, see ''line-break: anywhere''. white-space/break-spaces-before-first-char-011.html Note: This option enables the other common behavior for Ethiopic. It is also often used in a context where the text consists predominantly of CJK characters with only short non-CJK excerpts, and it is desired that the text be better distributed on each line.

keep-all

Breaking is forbidden within “words”: implicit soft wrap opportunities between typographic letter units (or other typographic character units belonging to the NU, AL, AI, or ID Unicode line breaking classes [[!UAX14]]) are suppressed, i.e. breaks are prohibited between pairs of such characters (regardless of 'line-break' settings other than ''line-break/anywhere'') except where opportunities exist due to dictionary-based breaking. Otherwise this option is equivalent to ''word-break/normal''. In this style, sequences of CJK characters do not break. word-break/word-break-keep-all-000.html word-break/word-break-keep-all-001.html word-break/word-break-keep-all-002.html word-break/word-break-keep-all-003.html

Note: This is the other common behavior for Korean (which uses [=spaces=] between words), and is also useful for mixed-script text where CJK snippets are mixed into another language that uses [=spaces=] for separation.

Symbols that line-break the same way as letters of a particular category are affected the same way as those letters.

        这是一些汉字 and some Latin و کمی خط عربی และตัวอย่างการเขียนภาษาไทย በጽሑፍ፡ማራዘሙን፡አንዳንድ፡
      

      <h1>窓ぎわの<wbr>トットちゃん</h1>
      

          窓ぎわのトットちゃ
          ん

          窓ぎわの
          トットちゃん

When shaping scripts such as Arabic are allowed to break within words due to ''word-break/break-all'' the characters must still be shaped as if the word were not broken (see [[#word-break-shaping]]). word-break/word-break-break-all-004.html

For compatibility with legacy content, the 'word-break' property also supports a deprecated break-word keyword. When specified, this has the same effect as ''word-break: normal'' and ''overflow-wrap: anywhere'', regardless of the actual value of the 'overflow-wrap' property. white-space/pre-wrap-008.html white-space/pre-wrap-016.html word-break/word-break-break-word-overflow-wrap-interactions.html word-break/word-break-break-word-crash-001.html white-space/break-spaces-003.html white-space/break-spaces-004.html white-space/break-spaces-008.html white-space/break-spaces-before-first-char-010.html word-break/word-break-min-content-001.html word-break/word-break-min-content-002.html word-break/word-break-min-content-003.html word-break/word-break-min-content-004.html word-break/word-break-min-content-005.html word-break/word-break-min-content-006.html

Line Breaking Strictness: the 'line-break' property

    Name: line-break
    Value: auto | loose | normal | strict | anywhere
    Initial: auto
    Applies to: inline boxes
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    

This property specifies the strictness of line-breaking rules applied within an element: especially how wrapping interacts with punctuation and symbols. Values have the following meanings:

auto

The UA determines the set of line-breaking restrictions to use, and it may vary the restrictions based on the length of the line; e.g., use a less restrictive set of line-break rules for short lines.

loose

Breaks text using the least restrictive set of line-breaking rules. Typically used for short lines, such as in newspapers.

normal

Breaks text using the most common set of line-breaking rules.

strict

Breaks text using the most stringent set of line-breaking rules.

anywhere

There is a soft wrap opportunity around every typographic character unit, including around any punctuation character or [=preserved white spaces=], or in the middle of words, disregarding any prohibition against line breaks, even those introduced by characters with the GL, WJ, or ZWJ character class (see [[UAX14]]) or mandated by the 'word-break' property. The different wrapping opportunities must not be prioritized. Hyphenation is not applied. line-break/line-break-anywhere-001.html line-break/line-break-anywhere-002.html line-break/line-break-anywhere-003.html line-break/line-break-anywhere-004.html line-break/line-break-anywhere-005.html line-break/line-break-anywhere-006.html line-break/line-break-anywhere-007.html line-break/line-break-anywhere-008.html line-break/line-break-anywhere-009.html line-break/line-break-anywhere-010.html line-break/line-break-anywhere-011.html line-break/line-break-anywhere-012.html line-break/line-break-anywhere-013.html line-break/line-break-anywhere-014.html line-break/line-break-anywhere-015.html line-break/line-break-anywhere-016.html line-break/line-break-anywhere-017.html line-break/line-break-anywhere-and-white-space-001.html line-break/line-break-anywhere-and-white-space-002.html line-break/line-break-anywhere-and-white-space-003.html line-break/line-break-anywhere-and-white-space-004.html line-break/line-break-anywhere-and-white-space-005.html line-break/line-break-anywhere-and-white-space-006.html line-break/line-break-anywhere-and-white-space-007.html line-break/line-break-anywhere-and-white-space-008.html line-break/line-break-anywhere-and-white-space-009.html line-break/line-break-anywhere-and-white-space-009.html line-break/line-break-anywhere-overrides-uax-behavior-001.html line-break/line-break-anywhere-overrides-uax-behavior-002.html line-break/line-break-anywhere-overrides-uax-behavior-003.html line-break/line-break-anywhere-overrides-uax-behavior-004.html line-break/line-break-anywhere-overrides-uax-behavior-005.html line-break/line-break-anywhere-overrides-uax-behavior-006.html line-break/line-break-anywhere-overrides-uax-behavior-007.html line-break/line-break-anywhere-overrides-uax-behavior-008.html line-break/line-break-anywhere-overrides-uax-behavior-009.html line-break/line-break-anywhere-overrides-uax-behavior-010.html line-break/line-break-anywhere-overrides-uax-behavior-011.html line-break/line-break-anywhere-overrides-uax-behavior-012.html line-break/line-break-anywhere-overrides-uax-behavior-013.html line-break/line-break-anywhere-overrides-uax-behavior-014.html line-break/line-break-anywhere-overrides-uax-behavior-015.html line-break/line-break-anywhere-overrides-uax-behavior-016.html line-break/line-break-shaping-001.html white-space/break-spaces-before-first-char-007.html white-space/break-spaces-before-first-char-011.html Note: This value triggers the line breaking rules typically seen in terminals.

Note: ''line-break/anywhere'' only allows [=preserved white spaces=] at the end of the line to be wrapped to the next line when 'white-space' is set to ''white-space/break-spaces'', because in other cases: * [=preserved white space=] at the end/start of the line is discarded (''white-space/normal'', ''white-space/pre-line'') * wrapping is forbidden altoghether (''nowrap'', ''pre'') * the [=preserved white space=] [=hang=] (''pre-wrap''). When it does have an effect on [=preserved white space=], with ''white-space: break-spaces'', it allows breaking before the first space of a sequence, which ''break-spaces'' on its own does not.

line-break/line-break-anywhere-005.html white-space/break-spaces-before-first-char-007.html white-space/break-spaces-before-first-char-008.html white-space/break-spaces-before-first-char-009.html white-space/break-spaces-before-first-char-010.html

The rules here are following guidelines from KLREQ for Korean, which don't allow the Chinese/Japanese-specific breaks. However, the resulting behavior could use some review and feedback to make sure they are correct, particularly when “word basis” breaking is used (''word-break: keep-all'') in Korean.

CSS distinguishes between four levels of strictness in the rules for text wrapping. The precise set of rules in effect for each of ''line-break/loose'', ''line-break/normal'', and ''line-break/strict'' is up to the UA and should follow language conventions. However, this specification does require that:

• The following breaks are forbidden in ''strict'' line breaking and allowed in ''line-break/normal'' and ''loose'':
  • breaks before Japanese small kana or the Katakana-Hiragana prolonged sound mark, i.e. character from the Unicode line breaking class CJ [[!UAX14]]. line-break/line-break-loose-011.xht line-break/line-break-loose-012.xht line-break/line-break-normal-011.xht line-break/line-break-normal-012.xht line-break/line-break-strict-011.xht line-break/line-break-strict-012.xht i18n/ja/css-text-line-break-ja-cj-loose.html i18n/ja/css-text-line-break-ja-cj-normal.html i18n/ja/css-text-line-break-ja-cj-strict.html i18n/zh/css-text-line-break-zh-cj-loose.html i18n/zh/css-text-line-break-zh-cj-normal.html i18n/zh/css-text-line-break-zh-cj-strict.html i18n/other-lang/css-text-line-break-de-cj-loose.html i18n/other-lang/css-text-line-break-de-cj-normal.html i18n/other-lang/css-text-line-break-de-cj-strict.html i18n/unknown-lang/css-text-line-break-cj-loose.html i18n/unknown-lang/css-text-line-break-cj-normal.html i18n/unknown-lang/css-text-line-break-cj-strict.html
• The following breaks are allowed for ''line-break/normal'' and ''loose'' line breaking if the writing system is Chinese or Japanese, and are otherwise forbidden:
  • breaks before certain CJK hyphen-like characters:
    〜 U+301C, ゠ U+30A0 line-break/line-break-loose-013.xht line-break/line-break-normal-013.xht line-break/line-break-strict-013.xht i18n/ja/css-text-line-break-ja-hyphens-loose.html i18n/ja/css-text-line-break-ja-hyphens-normal.html i18n/ja/css-text-line-break-ja-hyphens-strict.html i18n/zh/css-text-line-break-zh-hyphens-loose.html i18n/zh/css-text-line-break-zh-hyphens-normal.html i18n/zh/css-text-line-break-zh-hyphens-strict.html i18n/other-lang/css-text-line-break-de-hyphens-loose.html i18n/other-lang/css-text-line-break-de-hyphens-normal.html i18n/other-lang/css-text-line-break-de-hyphens-strict.html i18n/unknown-lang/css-text-line-break-hyphens-loose.html i18n/unknown-lang/css-text-line-break-hyphens-normal.html i18n/unknown-lang/css-text-line-break-hyphens-strict.html writing-system/writing-system-line-break-001.html
• The following breaks are allowed for ''loose'' line breaking if the preceding character belongs to the Unicode line breaking class ID [[!UAX14]] (including when the preceding character is treated as ID due to ''word-break: break-all''), and are otherwise forbidden:
  • breaks before hyphens:
    ‐ U+2010, – U+2013 line-break/line-break-loose-hyphens-001.html line-break/line-break-normal-hyphens-001.html line-break/line-break-strict-hyphens-001.html line-break/line-break-loose-hyphens-002.html line-break/line-break-normal-hyphens-002.html line-break/line-break-strict-hyphens-002.html line-break/line-break-loose-hyphens-003.html line-break/line-break-normal-hyphens-003.html line-break/line-break-strict-hyphens-003.html
• The following breaks are forbidden for ''line-break/normal'' and ''strict'' line breaking and allowed in ''loose'':
  • breaks before iteration marks:
    々 U+3005, 〻 U+303B, ゝ U+309D, ゞ U+309E, ヽ U+30FD, ヾ U+30FE line-break/line-break-loose-014.xht line-break/line-break-normal-014.xht line-break/line-break-strict-014.xht i18n/ja/css-text-line-break-ja-iteration-loose.html i18n/ja/css-text-line-break-ja-iteration-normal.html i18n/ja/css-text-line-break-ja-iteration-strict.html i18n/zh/css-text-line-break-zh-iteration-loose.html i18n/zh/css-text-line-break-zh-iteration-normal.html i18n/zh/css-text-line-break-zh-iteration-strict.html i18n/other-lang/css-text-line-break-de-iteration-loose.html i18n/other-lang/css-text-line-break-de-iteration-normal.html i18n/other-lang/css-text-line-break-de-iteration-strict.html i18n/unknown-lang/css-text-line-break-iteration-loose.html i18n/unknown-lang/css-text-line-break-iteration-normal.html i18n/unknown-lang/css-text-line-break-iteration-strict.html
  • breaks between inseparable characters (such as ‥ U+2025, … U+2026) i.e. characters from the Unicode line breaking class IN [[!UAX14]]. line-break/line-break-loose-015.xht line-break/line-break-normal-015a.xht line-break/line-break-normal-015b.xht line-break/line-break-strict-015a.xht line-break/line-break-strict-015b.xht i18n/ja/css-text-line-break-ja-in-loose.html i18n/ja/css-text-line-break-ja-in-normal.html i18n/ja/css-text-line-break-ja-in-strict.html i18n/zh/css-text-line-break-zh-in-loose.html i18n/zh/css-text-line-break-zh-in-normal.html i18n/zh/css-text-line-break-zh-in-strict.html i18n/other-lang/css-text-line-break-de-in-loose.html i18n/other-lang/css-text-line-break-de-in-normal.html i18n/other-lang/css-text-line-break-de-in-strict.html i18n/unknown-lang/css-text-line-break-in-loose.html i18n/unknown-lang/css-text-line-break-in-normal.html i18n/unknown-lang/css-text-line-break-in-strict.html
• The following breaks are allowed for ''loose'' if the writing system is Chinese or Japanese and are otherwise forbidden:
  • breaks before certain centered punctuation marks:
    ・ U+30FB, ： U+FF1A, ； U+FF1B, ･ U+FF65, ‼ U+203C, ⁇ U+2047, ⁈ U+2048, ⁉ U+2049, ！ U+FF01, ？ U+FF1F line-break/line-break-loose-016a.xht line-break/line-break-loose-016b.xht line-break/line-break-normal-016a.xht line-break/line-break-normal-016b.xht line-break/line-break-strict-016a.xht line-break/line-break-strict-016b.xht i18n/ja/css-text-line-break-ja-cpm-loose.html i18n/ja/css-text-line-break-ja-cpm-normal.html i18n/ja/css-text-line-break-ja-cpm-strict.html i18n/zh/css-text-line-break-zh-cpm-loose.html i18n/zh/css-text-line-break-zh-cpm-normal.html i18n/zh/css-text-line-break-zh-cpm-strict.html i18n/other-lang/css-text-line-break-de-cpm-loose.html i18n/other-lang/css-text-line-break-de-cpm-normal.html i18n/other-lang/css-text-line-break-de-cpm-strict.html i18n/unknown-lang/css-text-line-break-cpm-loose.html i18n/unknown-lang/css-text-line-break-cpm-normal.html i18n/unknown-lang/css-text-line-break-cpm-strict.html writing-system/writing-system-line-break-002.html
  • breaks before suffixes:
    Characters with the Unicode line breaking class PO [[!UAX14]] and the East Asian Width property [[!UAX11]] Ambiguous, Fullwidth, or Wide. line-break/line-break-loose-017a.xht line-break/line-break-loose-017b.xht line-break/line-break-normal-017a.xht line-break/line-break-normal-017b.xht line-break/line-break-strict-017a.xht line-break/line-break-strict-017b.xht i18n/ja/css-text-line-break-ja-po-loose.html i18n/ja/css-text-line-break-ja-po-normal.html i18n/ja/css-text-line-break-ja-po-strict.html i18n/zh/css-text-line-break-zh-po-loose.html i18n/zh/css-text-line-break-zh-po-normal.html i18n/zh/css-text-line-break-zh-po-strict.html i18n/other-lang/css-text-line-break-de-po-loose.html i18n/other-lang/css-text-line-break-de-po-normal.html i18n/other-lang/css-text-line-break-de-po-strict.html i18n/unknown-lang/css-text-line-break-po-loose.html i18n/unknown-lang/css-text-line-break-po-normal.html i18n/unknown-lang/css-text-line-break-po-strict.html
  • breaks after prefixes:
    Characters with the Unicode line breaking class PR [[!UAX14]] and the East Asian Width property [[!UAX11]] Ambiguous, Fullwidth, or Wide. line-break/line-break-loose-018.xht line-break/line-break-normal-018.xht line-break/line-break-strict-018.xht i18n/ja/css-text-line-break-ja-pr-loose.html i18n/ja/css-text-line-break-ja-pr-normal.html i18n/ja/css-text-line-break-ja-pr-strict.html i18n/zh/css-text-line-break-zh-pr-loose.html i18n/zh/css-text-line-break-zh-pr-normal.html i18n/zh/css-text-line-break-zh-pr-strict.html i18n/other-lang/css-text-line-break-de-pr-loose.html i18n/other-lang/css-text-line-break-de-pr-normal.html i18n/other-lang/css-text-line-break-de-pr-strict.html i18n/unknown-lang/css-text-line-break-pr-loose.html i18n/unknown-lang/css-text-line-break-pr-normal.html i18n/unknown-lang/css-text-line-break-pr-strict.html

Note: The requirements listed above only create distinctions in CJK text. In an implementation that matches only the rules above, and no additional rules, 'line-break' would only affect CJK code points unless the writing system is tagged as Chinese or Japanese. Future levels may add additional specific rules for other writing systems and languages as their requirements become known.

Note: The CSSWG recognizes that in a future edition of the specification finer control over line breaking may be necessary to satisfy high-end publishing requirements.

Hyphenation: the 'hyphens' property

Hyphenation is the controlled splitting of words where they usually would not be allowed to break to improve the layout of paragraphs, typically splitting words at syllabic or morphemic boundaries, and visually indicating the split (usually by inserting a hyphen, U+2010). In some cases, hyphenation may also alter the spelling of a word. Regardless, hyphenation is a rendering effect only: it must have no effect on the underlying document content or on text selection or searching.

Hyphenation occurs when the line breaks at a valid hyphenation opportunity, which is a type of soft wrap opportunity that exists within a word where hyphenation is allowed. In CSS hyphenation opportunities are controlled with the 'hyphens' property. CSS Text Level 3 does not define the exact rules for hyphenation; however UAs are strongly encouraged to optimize their choice of break points and to chose language-appropriate hyphenation points. hyphens/hyphens-overflow-001.html Note: The [=soft wrap opportunity=] introduced by the U+002D HYPHEN-MINUS character or the U+2010 HYPHEN character is not a [=hyphenation opportunity=], as no visual indication of the split is created when wrapping: these characters are visible whether the line is wrapped at that point or not. Hyphenation opportunities are considered when calculating min-content intrinsic sizes.

    Name: hyphens
    Value: none | manual | auto
    Initial: manual
    Applies to: inline boxes
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    

This property controls whether hyphenation is allowed to create more soft wrap opportunities within a line of text. Values have the following meanings:

none

Words are not hyphenated, even if characters inside the word explicitly define hyphenation opportunities. Note: This does not suppress the existing [=soft wrap opportunities=] introduced by always visible characters such as U+002D HYPHEN-MINUS or U+2010 HYPHEN. hyphens/hyphens-none-011.html hyphens/hyphens-none-012.html hyphens/hyphens-none-013.html

manual

Words are only hyphenated where there are characters inside the word that explicitly suggest hyphenation opportunities. hyphens/hyphens-overflow-001.html hyphens/hyphens-manual-010.html hyphens/hyphens-manual-011.html hyphens/hyphens-manual-012.html hyphens/hyphens-manual-013.html hyphens/hyphens-out-of-flow-001.html hyphens/hyphens-shaping-001.html hyphens/hyphens-shaping-002.html hyphens/hyphens-span-001.html hyphens/shy-styling-001.html

In Unicode, U+00AD is a conditional "soft hyphen" and U+2010 is an unconditional hyphen. Unicode Standard Annex #14 describes the role of soft hyphens in Unicode line breaking. [[!UAX14]] In HTML, &shy; represents the soft hyphen character, which suggests a hyphenation opportunity.

ex­ample

auto

Words may be broken at hyphenation opportunities determined automatically by a language-appropriate hyphenation resource in addition to those indicated explicitly by a conditional hyphen. Automatic hyphenation opportunities within a word must be ignored if the word contains a conditional hyphen (&shy; or U+00AD), in favor of the conditional hyphen(s). However, if, even after breaking at such opportunities, a portion of that word is is still too long to fit on one line, an automatic hyphenation opportunity may be used. hyphenation-control-1.html hyphens/hyphens-auto-001.html hyphens/hyphens-auto-010.html hyphens/hyphens-out-of-flow-002.html hyphens/hyphens-span-002.html Note: In some languages (such as English but not German), it may be appropriate to avoid having hyphenation opportunities in mixed case words, as those may indicate proper nouns. This type of heuristic is however not mandated by this specification, as it is up to the User Agent and its language-specific hyphenation resource.

Correct automatic hyphenation requires a hyphenation resource appropriate to the language of the text being broken. The UA must therefore only automatically hyphenate text for which the content language is known and for which it has an appropriate hyphenation resource. hyphens/hyphens-auto-001.html

For the purpose of the 'hyphens' property, what constitutes a “word” is UA-dependent. However, inline element boundaries and out-of-flow elements must be ignored when determining word boundaries. hyphens/hyphens-span-001.html hyphens/hyphens-span-002.html hyphens/hyphens-out-of-flow-001.html hyphens/hyphens-out-of-flow-002.html

Authors should correctly tag their content’s language (e.g. using the HTML lang attribute or XML xml:lang attribute) in order to obtain correct automatic hyphenation. The character or characters visually shown due to hyphenation at a [=hyphenation opportunity=] created by a conditional hyphen character (&shy; or U+00AD) are inserted in-place, and styled according to any property that applies to the conditional hyphen character. hyphens/shy-styling-001.html

ex<span style="color:red">&shy;</span>ample

When shaping scripts such as Arabic are allowed to break within words due to hyphenation, the characters must still be shaped as if the word were not broken (see [[#word-break-shaping]]). hyphens/hyphens-shaping-001.html hyphens/hyphens-shaping-002.html

Overflow Wrapping: the 'overflow-wrap'/'word-wrap' property

  Name: overflow-wrap, word-wrap
  Value: normal | break-word | anywhere
  Initial: normal
  Applies to: inline boxes
  Inherited: yes
  Canonical order: n/a
  Computed value: specified keyword
  Animation type: discrete
  

This property specifies whether the UA may break at otherwise disallowed points within a line to prevent overflow, when an otherwise-unbreakable string is too long to fit within the line box. It only has an effect when 'white-space' allows wrapping. Possible values:

normal

Lines may break only at allowed break points. However, the restrictions introduced by ''word-break: keep-all'' may be relaxed to match ''word-break: normal'' if there are no otherwise-acceptable break points in the line.

overflow-wrap/overflow-wrap-004.html overflow-wrap/overflow-wrap-normal-keep-all-001.html

anywhere

An otherwise unbreakable sequence of characters may be broken at an arbitrary point if there are no otherwise-acceptable break points in the line. Shaping characters are still shaped as if the word were not broken, and grapheme clusters must stay together as one unit. No hyphenation character is inserted at the break point. Soft wrap opportunities introduced by ''overflow-wrap/anywhere'' are considered when calculating min-content intrinsic sizes. overflow-wrap/overflow-wrap-min-content-size-001.html overflow-wrap/overflow-wrap-min-content-size-002.html overflow-wrap/overflow-wrap-min-content-size-003.html overflow-wrap/overflow-wrap-anywhere-001.html overflow-wrap/overflow-wrap-anywhere-003.html overflow-wrap/overflow-wrap-anywhere-006.html overflow-wrap/overflow-wrap-anywhere-007.html overflow-wrap/overflow-wrap-anywhere-008.html overflow-wrap/overflow-wrap-anywhere-009.html overflow-wrap/overflow-wrap-anywhere-010.html overflow-wrap/overflow-wrap-anywhere-inline-001.html overflow-wrap/overflow-wrap-anywhere-inline-002.html overflow-wrap/overflow-wrap-anywhere-inline-003.html overflow-wrap/overflow-wrap-anywhere-inline-004.html overflow-wrap/overflow-wrap-anywhere-fit-content-001.html overflow-wrap/overflow-wrap-min-content-size-005.html overflow-wrap/overflow-wrap-min-content-size-007.html overflow-wrap/overflow-wrap-cluster-002.html overflow-wrap/overflow-wrap-shaping-002.html white-space/break-spaces-before-first-char-009.html white-space/break-spaces-before-first-char-013.html word-break/word-break-min-content-001.html word-break/word-break-min-content-002.html word-break/word-break-min-content-003.html word-break/word-break-min-content-004.html word-break/word-break-min-content-005.html word-break/word-break-min-content-006.html white-space/pre-wrap-009.html white-space/pre-wrap-010.html white-space/break-spaces-with-overflow-wrap-002.html white-space/break-spaces-with-overflow-wrap-004.html white-space/break-spaces-with-overflow-wrap-006.html white-space/break-spaces-with-overflow-wrap-008.html white-space/break-spaces-with-overflow-wrap-010.html

break-word

As for ''overflow-wrap/anywhere'' except that soft wrap opportunities introduced by ''overflow-wrap/break-word'' are not considered when calculating min-content intrinsic sizes. overflow-wrap/overflow-wrap-001.html overflow-wrap/overflow-wrap-break-word-001.html overflow-wrap/overflow-wrap-break-word-003.html overflow-wrap/overflow-wrap-break-word-008.html overflow-wrap/overflow-wrap-break-word-009.html overflow-wrap/overflow-wrap-break-word-010.html overflow-wrap/overflow-wrap-min-content-size-004.html overflow-wrap/overflow-wrap-min-content-size-006.html overflow-wrap/overflow-wrap-min-content-size-008.html overflow-wrap/overflow-wrap-break-word-fit-content-001.html overflow-wrap/overflow-wrap-cluster-001.html overflow-wrap/overflow-wrap-shaping-001.html white-space/break-spaces-before-first-char-008.html white-space/break-spaces-before-first-char-012.html overflow-wrap/overflow-wrap-break-word-keep-all-001.html white-space/break-spaces-with-overflow-wrap-001.html white-space/break-spaces-with-overflow-wrap-003.html white-space/break-spaces-with-overflow-wrap-005.html white-space/break-spaces-with-overflow-wrap-007.html white-space/break-spaces-with-overflow-wrap-009.html

For legacy reasons, UAs must treat 'word-wrap' as a [=legacy name alias=] of the 'overflow-wrap' property. overflow-wrap/word-wrap-alias.html overflow-wrap/word-wrap-001.html overflow-wrap/word-wrap-002.html overflow-wrap/word-wrap-004.html

Shaping Across Intra-word Breaks

When shaping scripts such as Arabic wrap at unforced soft wrap opportunities within words (such as when breaking due to ''word-break: break-all'', ''line-break: anywhere'', ''overflow-wrap: break-word'', ''overflow-wrap: anywhere'', or when hyphenating) the characters must still be shaped (their joining forms chosen) as if the word were still whole. hyphens/hyphens-shaping-001.html hyphens/hyphens-shaping-002.html line-break/line-break-shaping-001.html overflow-wrap/overflow-wrap-shaping-001.html overflow-wrap/overflow-wrap-shaping-002.html word-break/word-break-break-all-004.html

Alignment and Justification

Alignment and justification controls how inline content is distributed within a line box.

Text Alignment: the 'text-align' shorthand

    Name: text-align
    Value: start | end | left | right | center | justify | match-parent | justify-all
    Initial: start
    Applies to: block containers
    Inherited: yes
    Canonical order: n/a
    Animation type: discrete
    

This shorthand property sets the 'text-align-all' and 'text-align-last' properties and describes how the inline-level content of a block is aligned along the inline axis if the content does not completely fill the line box. Values other than ''justify-all'' or ''match-parent'' are assigned to 'text-align-all' and reset 'text-align-last' to ''text-align-last/auto''. Values have the following meanings:

start

Inline-level content is aligned to the start edge of the line box. text-align/text-align-006.html text-align/text-align-start-001.html text-align/text-align-start-002.html text-align/text-align-start-003.html text-align/text-align-start-004.html text-align/text-align-start-005.html text-align/text-align-start-006.html text-align/text-align-start-007.html text-align/text-align-start-008.html text-align/text-align-start-009.html text-align/text-align-start-010.html text-align/text-align-start-014.html text-align/text-align-start-015.html text-align/text-align-start-016.html text-align/text-align-start-017.html

end

Inline-level content is aligned to the end edge of the line box. text-align/text-align-007.html text-align/text-align-end-001.html text-align/text-align-end-002.html text-align/text-align-end-003.html text-align/text-align-end-004.html text-align/text-align-end-005.html text-align/text-align-end-006.html text-align/text-align-end-007.html text-align/text-align-end-008.html text-align/text-align-end-009.html text-align/text-align-end-010.html text-align/text-align-end-014.html text-align/text-align-end-015.html text-align/text-align-end-016.html text-align/text-align-end-017.html

left

Inline-level content is aligned to the line left edge of the line box. (In vertical writing modes, this will be either the physical top or bottom, depending on 'text-orientation'.) [[CSS-WRITING-MODES-3]]

right

Inline-level content is aligned to the line right edge of the line box. (In vertical writing modes, this will be either the physical top or bottom, depending on 'text-orientation'.) [[CSS-WRITING-MODES-3]]

center

Inline-level content is centered within the line box.

justify

Text is justified according to the method specified by the 'text-justify' property, in order to exactly fill the line box. Unless otherwise specified by 'text-align-last', the last line before a forced break or the end of the block is ''start''-aligned. text-align/text-align-justify-001.html text-align/text-align-justify-002.html text-align/text-align-justify-003.html text-align/text-align-justify-004.html text-align/text-align-justify-005.html text-align/text-align-justify-006.html letter-spacing-justify-001.xht text-align-white-space-002.xht text-align-white-space-004.xht text-align-white-space-006.xht text-align-white-space-008.xht word-spacing-justify-001.xht

justify-all

Sets both 'text-align-all' and 'text-align-last' to ''text-align/justify'', forcing the last line to justify as well. text-align/text-align-justifyall-001.html text-align/text-align-justifyall-002.html text-align/text-align-justifyall-003.html text-align/text-align-justifyall-004.html text-align/text-align-justifyall-005.html text-align/text-align-justifyall-006.html letter-spacing/letter-spacing-bidi-003.xht

match-parent

This value behaves the same as ''inherit'' (computes to its parent's computed value) except that an inherited value of ''start'' or ''end'' is interpreted against the parent’s (or the initial containing block’s, if there is no parent) 'direction' value and results in a computed value of either 'left' or 'right'. When specified on the 'text-align' shorthand, sets both 'text-align-all' and 'text-align-last' to ''text-align/match-parent''. text-align/text-align-008.html text-align-match-parent-01.html text-align-match-parent-02.html text-align-match-parent-03.html text-align-match-parent-04.html text-align-match-parent-root-ltr.html text-align-match-parent-root-rtl.html

A block of text is a stack of line boxes. This property specifies how the inline-level boxes within each line box align with respect to the start and end sides of the line box. Alignment is not with respect to the viewport or containing block.

In the case of ''justify'', the UA may stretch or shrink any inline boxes by adjusting their text. (See 'text-justify'.) If an element's [=white space=] is not collapsible, then the UA is not required to adjust its text for the purpose of justification and may instead treat the text as having no justification opportunities. If the UA chooses to adjust the text, then it must ensure that tab stops continue to line up as required by the white space processing rules. text-align-white-space-001.xht text-align-white-space-003.xht text-align-white-space-005.xht text-align-white-space-007.xht

If (after justification, if any) the inline contents of a line box are too long to fit within it, then the contents are start-aligned: any content that doesn't fit overflows the line box's end edge.

See Bidirectionality and line boxes for details on how to determine the start and end edges of a line box.

Default Text Alignment: the 'text-align-all' property

    Name: text-align-all
    Value: start | end | left | right | center | justify | match-parent
    Initial: start
    Applies to: block containers
    Inherited: yes
    Computed value: keyword as specified, except for ''match-parent'' which computes as defined above
    Canonical order: n/a
    Animation type: discrete
    

This longhand of the 'text-align' shorthand property specifies the inline alignment of all lines of inline content in the block container, except for last lines overridden by a non-''text-align-last/auto'' value of 'text-align-last'. See 'text-align' for a full description of values.

Authors should use the 'text-align' shorthand instead of this property.

Last Line Alignment: the 'text-align-last' property

    Name: text-align-last
    Value: auto | start | end | left | right | center | justify | match-parent
    Initial: auto
    Applies to: block containers
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    

This property describes how the last line of a block or a line right before a forced line break is aligned. text-align/text-align-last-010.html text-align/text-align-last-011.html text-align/text-align-last-wins-001.html

If auto is specified, content on the affected line is aligned per 'text-align-all' unless 'text-align-all' is set to ''justify'', in which case it is start-aligned. All other values are interpreted as described for 'text-align'.

Justification Method: the 'text-justify' property

    Name: text-justify
    Value: auto | none | inter-word | inter-character
    Initial: auto
    Applies to: inline boxes
    Inherited: yes
    Canonical order: n/a
    Computed value: specified keyword
    Animation type: discrete
    

This property selects the justification method used when a line's alignment is set to ''justify'' (see 'text-align'). The property applies to inlines, but is inherited from block containers to the root inline box containing their inline-level contents. It takes the following values:

auto

The UA determines the justification algorithm to follow, based on a balance between performance and adequate presentation quality. Since justification rules vary by writing system and language, UAs should, where possible, use a justification algorithm appropriate to the text. text/letter-spacing-justify-001.xht text/word-spacing-justify-001.xht

For example, the UA could use by default a justification method that is a simple universal compromise for all writing systems—such as primarily expanding word separators and between CJK typographic letter units along with secondarily expanding between Southeast Asian typographic letter units. Then, in cases where the content language of the paragraph is known, it could choose a more language-tailored justification behavior e.g. following [[JLREQ]] for Japanese, using cursive elongation for Arabic, using ''inter-word'' for German, etc.

An example of cursively-justified Arabic text, rendered by Tasmeem. Like English, Arabic can be justified by adjusting the spacing between words, but in most styles it can also be justified by calligraphically elongating or compressing the letterforms themselves. In this example, the upper text is extended to fill the line by the use of elongated (kashida) forms and swash forms, while the bottom line is compressed slightly by using a stacked combination for the characters between ت and م. By employing traditional calligraphic techniques, a typesetter can justify the line while preserving flow and color, providing a very high quality justification effect. However, this is by its nature a very script-specific effect.

Mixed-script text with ''text-justify: auto'': this interpretation uses a universal-compromise justification method, expanding at spaces as well as between CJK and Southeast Asian letters. This effectively uses inter-word + inter-ideograph spacing for lines that have word-separators and/or CJK characters and falls back to inter-cluster behavior for lines that don't or for which the space stretches too far.

none

Justification is disabled: there are no justification opportunities within the text. text-justify/text-justify-001.html text-justify/text-justify-006.html text-justify-none-001.html

Mixed-script text with ''text-justify: none''

Note: This value is intended for use in user stylesheets to improve readability or for accessibility purposes.

inter-word

Justification adjusts spacing at word separators only (effectively varying the used 'word-spacing' on the line). This behavior is typical for languages that separate words using spaces, like English or Korean. text-justify-inter-word-001.html

Mixed-script text with ''text-justify: inter-word''

inter-character

Justification adjusts spacing between each pair of adjacent typographic character units (effectively varying the used 'letter-spacing' on the line). This value is sometimes used in East Asian systems such as Japanese. text-justify-inter-character-001.html

Mixed-script text with ''text-justify: inter-character''

For legacy reasons, UAs must also support the alternate keyword distribute with the exact same meaning and behavior. text-justify-distribute-001.html

Since optimal justification is language-sensitive, authors should correctly language-tag their content for the best results. Note: The guidelines in this level of CSS do not describe a complete justification algorithm. They are merely a minimum set of requirements that a complete algorithm should meet. Limiting the set of requirements gives UAs some latitude in choosing a justification algorithm that meets their needs and desired balance of quality, speed, and complexity.

Expanding and Compressing Text

When justifying text, the user agent takes the remaining space between the ends of a line's contents and the edges of its line box, and distributes that space throughout its contents so that the contents exactly fill the line box. The user agent may alternatively distribute negative space, putting more content on the line than would otherwise fit under normal spacing conditions.

A justification opportunity is a point where the justification algorithm may alter spacing within the text. A justification opportunity can be provided by a single typographic character unit (such as a word separator), or by the juxtaposition of two typographic character units. As with controls for soft wrap opportunities, whether a typographic character unit provides a justification opportunity is controlled by the 'text-justify' value of its parent; similarly, whether a justification opportunity exists between two consecutive typographic character units is determined by the 'text-justify' value of their nearest common ancestor.

Space distributed by justification is in addition to the spacing defined by the 'letter-spacing' or 'word-spacing' properties. When such additional space is distributed to a word separator justification opportunity, it is applied under the same rules as for 'word-spacing'. Similarly, when space is distributed to an justification opportunity between two typographic character units, it is applied under the same rules as for 'letter-spacing'.

A justification algorithm may divide justification opportunities into different priority levels. All justification opportunities within a given level are expanded or compressed at the same priority, regardless of which typographic character units created that opportunity. For example, if justification opportunities between two Han characters and between two Latin letters are defined to be at the same level (as they are in the ''inter-character'' justification style), they are not treated differently because they originate from different typographic character units. It is not defined in this level whether or how other factors (such as font size, letter-spacing, glyph shape, position within the line, etc.) may influence the distribution of space to justification opportunities within the line.

The UA may enable or break optional ligatures or use other font features such as alternate glyphs or glyph compression to help justify the text under any method. This behavior is not controlled by this level of CSS. However, UAs must not break required ligatures or otherwise disable features required to correctly shape complex scripts.

If a justification opportunity exists within a line, and text alignment specifies full justification (''text-align/justify'') for that line, it must be justified.

Handling Symbols and Punctuation

When determining justification opportunities, a typographic character unit from the Unicode Symbols (S*) and Punctuation (P*) classes is generally treated the same as a typographic letter unit of the same script (or, if the character's script property is Common, then as a typographic letter unit of the dominant script).

However, by typographic tradition there may be additional rules controlling the justification of symbols and punctuation. Therefore, the UA may reassign specific characters or introduce additional levels of prioritization to handle justification opportunities involving symbols and punctuation.

For example, there are traditionally no justification opportunities between consecutive U+2014 Em Dash ‘—’, U+2015 Horizontal Bar ‘―’, U+2026 Horizontal Ellipsis ‘…’, or U+2025 Two Dot Leader ‘‥’ characters [[JLREQ]]; thus a UA might assign these characters to a “never” prioritization level. As another example, certain fullwidth punctuation characters (such as U+301A Left White Square Bracket ‘〚’) are considered to contain a justification opportunity in Japanese. The UA might therefore assign these characters to a higher prioritization level than the opportunities between ideographic characters.

Unexpandable Text

If the inline contents of a line cannot be stretched to the full width of the line box, then they must be aligned as specified by the 'text-align-last' property. (If 'text-align-last' is ''justify'', then they must be aligned as for ''center''.) text-align/text-align-last-empty-inline.html

Cursive Scripts

Justification must not introduce gaps between the joined typographic letter units of cursive scripts such as Arabic. If it is able, the UA may translate space distributed to justification opportunities within a run of such typographic letter units into some form of cursive elongation for that run. It otherwise must assume that no justification opportunity exists between any pair of typographic letter units in cursive script (regardless of whether they join).

Some font designs allow for the use of the tatweel character for justification. A UA that performs tatweel-based justification must properly handle the rules for its use. Note that correct insertion of tatweel characters depends on context, including the letter-combinations involved, location within the word, and location of the word within the line.

Minimum Requirements for ''text-justify/auto'' Justification

For auto justification, this specification does not define what all of the justification opportunities are, how they are prioritized, or when and how multiple levels of justification opportunities interact. However, it does require that

• Unless contraindicated by the typographic traditions of the content language or adjacent symbols/punctuation, each of the following provides a justification opportunity:
  • Word separators
  • The boundary between a typographic character unit of any block scripts and any other typographic character unit
  • The boundary between a typographic character unit of any clustered scripts and any other typographic character unit
• All letters belonging to all block scripts are treated the same, and all letters belonging to all clustered scripts are treated the same. For example, no distiction is made between the justification opportunity between a Han letter followed by another Han letter, vs. the justification opportunity between a Han letter followed by a Hangul letter.

Spacing

CSS offers control over text spacing via the 'word-spacing' and 'letter-spacing' properties, which specify additional space around word separators or between typographic character units, respectively.

Word Spacing: the 'word-spacing' property

  Name: word-spacing
  Value: normal | <>
  Initial: normal
  Applies to: inline boxes
  Inherited: yes
  Percentages: N/A
  Computed value: an absolute length
  Animation type: by computed value type
  Canonical order: n/a
  

This property specifies additional spacing between “words”. Missing values are assumed to be ''word-spacing:normal''. Values are interpreted as defined below:

normal

No additional spacing is applied. Computes to zero. word-spacing-100.xht

<length>

Specifies extra spacing in addition to the intrinsic inter-word spacing defined by the font. tab-size/tab-size-spacing-001.html word-spacing-004.xht word-spacing-005.xht word-spacing-006.xht word-spacing-007.xht word-spacing-008.xht word-spacing-016.xht word-spacing-017.xht word-spacing-018.xht word-spacing-019.xht word-spacing-020.xht word-spacing-028.xht word-spacing-029.xht word-spacing-030.xht word-spacing-031.xht word-spacing-032.xht word-spacing-040.xht word-spacing-041.xht word-spacing-042.xht word-spacing-043.xht word-spacing-044.xht word-spacing-052.xht word-spacing-053.xht word-spacing-054.xht word-spacing-055.xht word-spacing-056.xht word-spacing-064.xht word-spacing-065.xht word-spacing-066.xht word-spacing-067.xht word-spacing-068.xht word-spacing-076.xht word-spacing-077.xht word-spacing-078.xht word-spacing-079.xht word-spacing-080.xht word-spacing-088.xht word-spacing-089.xht word-spacing-090.xht word-spacing-091.xht word-spacing-092.xht word-spacing-097.xht word-spacing-098.xht word-spacing-099.xht

Additional spacing is applied to each word separator left in the text after the white space processing rules have been applied, and should be applied half on each side of the character unless otherwise dictated by typographic tradition. Values may be negative, but there may be implementation-dependent limits. word-spacing-remove-space-001.xht word-spacing-remove-space-002.xht word-spacing-remove-space-003.xht word-spacing-remove-space-004.xht word-spacing-remove-space-005.xht word-spacing-remove-space-006.xht

Word-separator characters are typographic character units whose purpose and general usage is to separate words. In [[UNICODE]] this includes the space (U+0020), the no-break space (U+00A0), the Ethiopic word space (U+1361), the Aegean word separators (U+10100,U+10101), the Ugaritic word divider (U+1039F), and the Phoenician Word Separator (U+1091F). word-spacing-characters-001.xht If there are no word-separator characters, or if a word-separating character has a zero advance width (such as the zero width space U+200B) then the user agent must not create an additional spacing between words. word-spacing-characters-003.xht General punctuation (from U+2000 to U+206F) and fixed-width spaces (such as U+3000 and U+2000 through U+200A) are not considered word-separator characters.

Tracking: the 'letter-spacing' property

    Name: letter-spacing
    Value: normal | <>
    Initial: normal
    Applies to: inline boxes
    Inherited: yes
    Computed value: an absolute length
    Animation type: by computed value type
    Canonical order: n/a
    

This property specifies additional spacing (commonly called tracking) between adjacent typographic character units. Letter-spacing is applied after bidi reordering [[CSS-WRITING-MODES-3]] and is in addition to kerning [[CSS-FONTS-3]] and 'word-spacing'. Depending on the justification rules in effect, user agents may further increase or decrease the space between typographic character units in order to justify text. letter-spacing/letter-spacing-bidi-001.html letter-spacing/letter-spacing-bidi-004.xht letter-spacing/letter-spacing-nesting-003.xht letter-spacing/letter-spacing-bidi-003.xht letter-spacing/letter-spacing-bidi-004.xht letter-spacing/letter-spacing-bidi-005.xht letter-spacing/letter-spacing-206.html letter-spacing/letter-spacing-211.html letter-spacing/letter-spacing-212.html bidi-005.xht bidi-006.xht bidi-007.xht bidi-008.xht bidi-009.xht bidi-010.xht bidi-text/bidi-005a.xht bidi-text/bidi-005b.xht bidi-text/bidi-006a.xht bidi-text/bidi-006b.xht bidi-text/bidi-007b.xht bidi-text/bidi-008b.xht bidi-text/bidi-009b.xht bidi-text/bidi-010b.xht text/letter-spacing-justify-001.xht

Values have the following meanings:

normal

No additional spacing is applied. Computes to zero. letter-spacing-100.xht

<length>

Specifies additional spacing between typographic character units. Values may be negative, but there may be implementation-dependent limits. tab-size/tab-size-spacing-001.html letter-spacing-004.xht letter-spacing-005.xht letter-spacing-006.xht letter-spacing-007.xht letter-spacing-008.xht letter-spacing-016.xht letter-spacing-017.xht letter-spacing-018.xht letter-spacing-019.xht letter-spacing-020.xht letter-spacing-028.xht letter-spacing-029.xht letter-spacing-030.xht letter-spacing-031.xht letter-spacing-032.xht letter-spacing-040.xht letter-spacing-041.xht letter-spacing-042.xht letter-spacing-043.xht letter-spacing-044.xht letter-spacing-052.xht letter-spacing-053.xht letter-spacing-054.xht letter-spacing-055.xht letter-spacing-056.xht letter-spacing-064.xht letter-spacing-065.xht letter-spacing-066.xht letter-spacing-067.xht letter-spacing-068.xht letter-spacing-076.xht letter-spacing-077.xht letter-spacing-078.xht letter-spacing-079.xht letter-spacing-080.xht letter-spacing-088.xht letter-spacing-089.xht letter-spacing-090.xht letter-spacing-091.xht letter-spacing-092.xht letter-spacing-097.xht letter-spacing-098.xht letter-spacing-099.xht letter-spacing-101.xht letter-spacing-102.xht

For legacy reasons, a computed 'letter-spacing' of zero yields a resolved value (getComputedStyle() return value) of ''letter-spacing/normal''.

For the purpose of 'letter-spacing', each consecutive run of atomic inlines (such as images and inline blocks) is treated as a single typographic character unit. letter-spacing/letter-spacing-204.html

Letter-spacing must not be applied at the beginning or at the end of a line. letter-spacing/letter-spacing-end-of-line-001.html tab-size/tab-size-spacing-001.html letter-spacing/letter-spacing-200.html letter-spacing/letter-spacing-201.html white-space/white-space-letter-spacing-001.html

      p    { letter-spacing: 1em; }

      <p>abc</p>

Letter spacing between two typographic character units effectively “belongs” to the innermost element that contains the two typographic character units: the total letter spacing between two adjacent typographic character units (after bidi reordering) is specified by and rendered within the innermost element that contains the boundary between the two typographic character units. letter-spacing/letter-spacing-bidi-002.html letter-spacing/letter-spacing-bidi-004.xht letter-spacing/letter-spacing-bidi-005.xht letter-spacing/letter-spacing-nesting-001.html letter-spacing/letter-spacing-nesting-002.html letter-spacing/letter-spacing-nesting-003.xht letter-spacing/letter-spacing-203.html letter-spacing/letter-spacing-205.html

      p    { letter-spacing: 1em; }
      span { letter-spacing: 2em; }

      <p>a<span>bb</span>c</p>

      p    { letter-spacing: 1em; }
      span { letter-spacing: 2em; }

      <p>a<span>b</span>c</p>

      p    { letter-spacing: 1em; }

      <p>a<span>bb</span>c</p>

      p    { letter-spacing: 1em; }
      span { letter-spacing: 2em; }

      <!-- abc followed by Hebrew letters alef (א), bet (ב) and gimel (ג) -->
      <!-- Reordering will display these in reverse order. -->
      <p>ab<span>cא</span>בג</p>

Letter spacing ignores invisible zero-width formatting characters (such as those from the Unicode Cf category). Spacing must be added as if those characters did not exist in the document. letter-spacing/letter-spacing-control-chars-001.html letter-spacing/letter-spacing-202.html

For example, 'letter-spacing' applied to A​B is identical to AB, regardless of where any element boundaries might fall.

When the effective spacing between two characters is not zero (due to either justification or a non-zero value of 'letter-spacing'), user agents should not apply optional ligatures, i.e. those that are not defined as required for fundamentally correct glyph shaping. However, ligatures and other font features specified via the low-level 'font-feature-settings' property take precedence over this rule. See [[css-fonts-3#feature-precedence]].

Cursive Scripts

If it is able, the UA may apply letter spacing to cursive scripts by translating the total extra space to be distributed to a run of such letters into some form of cursive elongation (or compression, for negative tracking values) for that run that results in an equivalent total expansion (or compression) of the run. Otherwise, if the UA cannot expand text from a cursive script without breaking its cursive connections, it must not apply spacing between any pair of that script's typographic letter units at all (effectively treating each word as a single typographic letter unit for the purpose of letter-spacing). Both cases will result in an effective spacing of zero between such letters; however the former will preserve the sense of stretching out the text.

Shaping Across Element Boundaries

Edge Effects

Edge effects control the indentation of lines with respect to other lines in the block ('text-indent') and how content is measured at the start and end edges of a line ('hanging-punctuation').

First Line Indentation: the 'text-indent' property

    Name: text-indent
    Value: [ <> ] && hanging? && each-line?
    Initial: 0
    Applies to: block containers
    Inherited: yes
    Percentages: refers to block container’s own inline-axis inner size
    Computed value: computed <> value, plus any specified keywords
    Animation type: by computed value type
    Canonical order: per grammar
    

This property specifies the indentation applied to lines of inline content in a block. The indent is treated as a margin applied to the start edge of the line box. text-indent-010.xht text-indent-012.xht text-indent-013.xht text-indent-115.xht text-indent-on-blank-line-rtl-left-align.html text-indent-overflow-001.xht text-indent-overflow-002.xht text-indent-overflow-003.xht text-indent-overflow-004.xht text-indent-rtl-001.xht text-indent-rtl-002.xht

Unless otherwise specified by the ''each-line'' and/or hanging keywords, only lines that are the first formatted line [[!CSS2]] of an element are affected. For example, the first line of an anonymous block box is only affected if it is the first child of its parent element. text-indent-014.xht text-indent-wrap-001.xht

Values have the following meanings:

<length>

Gives the amount of the indent as an absolute length.

text-indent-004.xht text-indent-005.xht text-indent-006.xht text-indent-007.xht text-indent-008.xht text-indent-010.xht text-indent-012.xht text-indent-013.xht text-indent-014.xht text-indent-016.xht text-indent-017.xht text-indent-018.xht text-indent-019.xht text-indent-020.xht text-indent-028.xht text-indent-029.xht text-indent-030.xht text-indent-031.xht text-indent-032.xht text-indent-040.xht text-indent-041.xht text-indent-042.xht text-indent-043.xht text-indent-044.xht text-indent-052.xht text-indent-053.xht text-indent-054.xht text-indent-055.xht text-indent-056.xht text-indent-064.xht text-indent-065.xht text-indent-066.xht text-indent-067.xht text-indent-068.xht text-indent-076.xht text-indent-077.xht text-indent-078.xht text-indent-079.xht text-indent-080.xht text-indent-088.xht text-indent-089.xht text-indent-090.xht text-indent-091.xht text-indent-092.xht text-indent-109.xht text-indent-110.xht text-indent-111.xht text-indent-113.xht text-indent-114.xht text-indent-115.xht text-indent-intrinsic-001.xht text-indent-intrinsic-002.xht text-indent-intrinsic-003.xht text-indent-intrinsic-004.xht text-indent-on-blank-line-rtl-left-align.html text-indent-overflow-001.xht text-indent-overflow-002.xht text-indent-overflow-003.xht text-indent-overflow-004.xht text-indent-rtl-001.xht text-indent-rtl-002.xht

<percentage>

Gives the amount of the indent as a percentage of the block container’s own logical width text-indent-011.xht text-indent-100.xht text-indent-101.xht text-indent-102.xht text-indent-103.xht text-indent-104.xht text-indent-percent-001.xht Percentages must be treated as ''0'' for the purpose of calculating [=intrinsic size contributions=], but are always resolved normally when performing layout. text-indent/percentage-value-intrinsic-size.html text-indent/text-indent-percentage-001.xht text-indent/text-indent-percentage-002.html text-indent/text-indent-percentage-003.html text-indent/text-indent-percentage-004.html Note: This can lead to the element overflowing. It is not recommended to use percentage indents and intrinsic sizing toghether.

each-line

Indentation affects the first line of each block container and each line after a forced line break (but not lines after a soft wrap break).

hanging

Inverts which lines are affected.

             Since CSS1 it has been possible to
        indent the first line of a block element
        5em by setting the 'text-indent' property 
        to '5em'.
      

        In CSS3 we can instead indent all other
             lines of the block element by 5em
             by setting the 'text-indent' property
             to 'hanging 5em'.
      

           For example, in the middle of
        this paragraph is an equation,
        which is centered:
                     x + y = z
        The first line after the equation
        is flush (else it would look like
        we started a new paragraph).
      

        In a short line of text
        There need be no wrapping,
        But when we go on and on and on  
           and on,
        Sometimes a soft break
        Can help us stay on the page.
      

Note: Since the 'text-indent' property inherits, when specified on a block element, it will affect descendant inline-block elements. For this reason, it is often wise to specify 'text-indent: 0' on elements that are specified 'display: inline-block'.

Hanging Glyphs

When a glyph at the start or end edge of a line hangs, it is not considered when measuring the line's contents for fit, alignment, or justification. Depending on the line's alignment/justification, this can result in the mark being placed outside the line box. The [=hanging=] glyph is also not taken into account when computing intrinsic sizes (min-content size and max-content size), and any sizes derived thereof. (The interaction of this measurement and kerning is currently UA-defined; the CSSWG welcomes advice on this point.)

A hanging glyph is still enclosed inside its parent inline box and still participates in text justification: its character advance is just not measured when determining how much content fits on the line, how much the line's contents need to be expanded or compressed for justification, or how to position the content within the line box for text alignment. Effectively, the hanging glyph character advance is re-interpreted as an additional negative margin on the affected edge of its parent inline box; the line is otherwise laid out as usual. An overflowing [=hanging glyph=] should typically be considered [=ink overflow=] [[!CSS-OVERFLOW-3]] so as to avoid creating unnecessary scrollbars, but the UA may treat it as [=scrollable overflow=] when the content is editable or in other circumstances where treating it as [=scrollable overflow=] would be useful to the user. hanging-punctuation/hanging-scrollable-001.html white-space/white-space-intrinsic-size-019.html white-space/white-space-intrinsic-size-020.html

In some cases, a glyph at the end of a line can conditionally hang: it [=hangs=] only if it does not otherwise fit in the line prior to justification. It is not considered when measuring the line’s contents for fit; however, any part of it that does not fit is considered to [=hang=]. Glyphs that [=conditionally hang=] are not taken into account when computing [=min-content sizes=] and any sizes derived thereof, but they are taken into account for [=max-content sizes=] and any sizes derived thereof. white-space/white-space-intrinsic-size-013.html white-space/white-space-intrinsic-size-014.html white-space/white-space-intrinsic-size-017.html

Non-zero inline-axis borders or padding between a hangable glyph and the edge of the line prevent the glyph from hanging. For example, a period at the end of an inline box with end padding does not hang at the end edge of a line.

Multiple adjacent glyphs can hang together, however there may be limits on how many are allowed to hang (e.g. at most one punctuation character may hang at each edge of the line).

Hanging Punctuation: the 'hanging-punctuation' property

    Name: hanging-punctuation
    Value: none | [ first || [ force-end | allow-end ] || last ]
    Initial: none
    Applies to: inline boxes
    Inherited: yes
    Canonical order: per grammar
    Computed value: specified keyword(s)
    Animation type: discrete
    

This property determines whether a punctuation mark, if one is present, hangs and may be placed outside the line box (or in the indent) at the start or at the end of a line of text.

Note: If there is not sufficient padding on the block container, 'hanging-punctuation' can trigger overflow.

Values have the following meanings:

none

No punctuation character is made to hang.

first

An opening bracket or quote at the start of the first formatted line of an element hangs. This applies to all characters in the Unicode categories Ps, Pf, Pi plus the ASCII quote marks “'” U+0027 and “"” U+0022. hanging-punctuation/hanging-punctuation-first-001.xht

last

A closing bracket or quote at the end of the last formatted line of an element hangs. This applies to all characters in the Unicode categories Pe, Pf, Pi plus the ASCII quote marks “'” U+0027 and “"” U+0022. hanging-punctuation/hanging-punctuation-last-001.xht

force-end

A stop or comma at the end of a line hangs. hanging-punctuation/hanging-punctuation-force-end-001.xht

allow-end

A stop or comma at the end of a line conditionally hangs. hanging-punctuation/hanging-punctuation-allow-end-001.xht

At most one punctuation character may hang at each edge of the line.

Stops and commas allowed to hang include:

U+002C	,	COMMA
U+002E	.	FULL STOP
U+060C	،	ARABIC COMMA
U+06D4	۔	ARABIC FULL STOP
U+3001	、	IDEOGRAPHIC COMMA
U+3002	。	IDEOGRAPHIC FULL STOP
U+FF0C	，	FULLWIDTH COMMA
U+FF0E	．	FULLWIDTH FULL STOP
U+FE50	﹐	SMALL COMMA
U+FE51	﹑	SMALL IDEOGRAPHIC COMMA
U+FE52	﹒	SMALL FULL STOP
U+FF61	｡	HALFWIDTH IDEOGRAPHIC FULL STOP
U+FF64	､	HALFWIDTH IDEOGRAPHIC COMMA

The UA may include other characters as appropriate.

Note: The CSS Working Group would appreciate if UAs including other characters would inform the working group of such additions.

The ''allow-end'' and ''force-end'' are two variations of hanging punctuation used in East Asia.

        p {
          text-align: justify;
          hanging-punctuation: allow-end;
        }

        p {
          text-align: justify;
          hanging-punctuation: force-end;
        }
      

The punctuation at the end of the first line for ''allow-end'' does not hang, because it fits without hanging. However, if ''force-end'' is used, it is forced to hang. The justification measures the line without the hanging punctuation. Therefore when the line is expanded, the punctuation is pushed outside the line.

Bidirectionality and Line Boxes

The start and end edges of a line box are determined by the inline base direction of the line box. In most cases, this is given by its containing block's computed 'direction'.

However if its containing block has ''unicode-bidi: plaintext'' [[!CSS-WRITING-MODES-3]], the line box's inline base direction must be determined by the inline base direction of the bidi paragraph to which it belongs: that is, the bidi paragraph for which the line box holds content. An empty line box (i.e. one that contains no atomic inlines or characters other than the line-breaking character, if any), takes its inline base direction from the preceding line box (if any), or, if this is the first line box in the containing block, then from the 'direction' property of the containing block.

      <block style="unicode-bidi: plaintext">
        Latin
        و·کمی
        Latin
        و·کمی
        Latin
        و·کمی
      </block>

Note: The inline base direction determined here applies to the line box itself, and not to its contents. It affects 'text-align-all', 'text-align-last', 'text-indent', and 'hanging-punctuation', i.e. the position and alignment of its contents with respect to its edges. It does not affect the formatting or ordering of its content.

      <para style="display: block; direction: rtl; unicode-bidi:plaintext">
      <quote style="unicode-bidi:plaintext">שלום!</quote>", he said.
      </para>

"!שלום", he said.

      <fieldset style="direction: rtl">
      <textarea style="unicode-bidi:plaintext">

      Hello!

      </textarea>
      </fieldset>

Appendix A: Text Processing Order of Operations

The following list defines the order of text operations. (Implementations are not bound to this order as long as the resulting layout is the same.)

1. white space processing part I (pre-wrapping)
2. text transformation
3. text combination
4. text orientation [[!CSS-WRITING-MODES-3]]
5. text wrapping while applying per line:
   • indentation
   • bidirectional reordering [[!CSS2]] / [[!CSS-WRITING-MODES-3]]
   • white space processing part II
   • font/glyph selection and positioning [[!CSS2]] / [[!CSS-FONTS-3]]
   • 'letter-spacing' and 'word-spacing'
   • hanging punctuation
6. justification (which may affect glyph selection and/or text wrapping, looping back into that step)
7. text alignment

Appendix B: Conversion to Plaintext

This appendix is normative for the purpose of plaintext copy-paste operations.

When a CSS-rendered document is converted to a plaintext format, it is expected that:

• The 'text-transform' property has no effect.
• [[#white-space-phase-1]] is applied and any sequence of collapsible [=white space=] at the beginning of a block or immediately following a forced line break is removed.

Appendix C: Default UA Stylesheet

This appendix is informative, and is to help UA developers to implement a default stylesheet for HTML, but UA developers are free to ignore or modify as appropriate.

      /* make list items and option elements align together */
      li, option { text-align: match-parent; }

If you find any issues, recommendations to add, or corrections, please send the information to www-style@w3.org with [css-text] in the subject line.

Appendix D: Scripts and Spacing

This appendix is normative.

Typographic behavior varies somewhat by language, but varies drastically by writing system. This appendix categorizes some common scripts in Unicode 6.0 according to their justification and spacing behavior. Category descriptions are descriptive, not prescriptive; the determining factor is the prioritization of justification opportunities.

block scripts

CJK and by extension all Wide characters (see [[!UAX11]].) The following Unicode scripts are included: Bopomofo, Han, Hangul, Hiragana, Katakana, and Yi. Characters of the East Asian Width property Wide and Fullwidth are also included, but Ambiguous characters are included only if the writing system is Chinese, Korean, or Japanese.

clustered scripts

Clustered scripts have discrete units and break only at word boundaries, but do not use visible word separators. They prioritize stretching spaces, but comfortably admit inter-character spacing for justification. The clustered scripts include, but are not limited to, the following Unicode scripts: Khmer, Lao, Myanmar, New Tai Lue, Tai Le, Tai Tham, Tai Viet, Thai

cursive scripts

Cursive scripts do not admit gaps between their letters for either justification or 'letter-spacing'. The following Unicode scripts are included: Arabic, Mandaic, Mongolian, N'Ko, Phags Pa, Syriac

User agents should update this list as they update their Unicode support to handle as-yet-unencoded cursive scripts in future versions of Unicode, and are encouraged to ask the CSSWG to update this spec accordingly.

Should block and cluster scripts be merged? They have different tolerances for space-justification vs inter-character justification, but both admit both.

Appendix E. Characters and Properties

Unicode defines four code point-level properties that are referenced in CSS typesetting:

East Asian width property

Defined in [[!UAX11]] and given as the East_Asian_Width property in the Unicode Character Database [[!UAX44]].

general category

Defined in [[!UAX44]] and given as the General_Category property in the Unicode Character Database [[!UAX44]].

script property

Defined in [[!UAX24]] and given as the Script property in the Unicode Character Database [[!UAX44]]. (UAs must include any ScriptExtensions.txt assignments in this mapping.)

Vertical Orientation

Defined in [[!UTR50]] as the Vertical_Orientation property and given in the UTR50 data file.

Unicode defines properties for individual code points, but sometimes it is necessary to determine the properties of a typographic character unit. For the purposes of CSS Text, the properties of a typographic character unit are given by the base character of its first grapheme cluster—except in two cases:

• Grapheme clusters formed with an Enclosing Mark (Me) of the Common script are considered to be Other Symbols (So) in the Common script. They are assumed to have the same Unicode properties as the Replacement Character U+FFFD.
• Grapheme clusters formed with a Space Separator (Zs) as the base are considered to be Modifier Symbols (Sk). They are assumed to have the same East Asian Width property as the base, but take their other properties from the first combining character in the sequence.

Appendix F. Space-Discarding Unicode Characters

This appendix is normative.

Appendix G. Identifying the Content Writing System

This appendix is normative.

Appendix H. Small Kana Mappings

Privacy and Security Considerations

Acknowledgements

This specification would not have been possible without the help from: Ayman Aldahleh, Bert Bos, Tantek Çelik, James Clark, Emilio Cobos Álvarez, Stephen Deach, John Daggett, Martin Dürst, Laurie Anna Edlund, Ben Errez, Yaniv Feinberg, Arye Gittelman, Ian Hickson, Martin Heijdra, Richard Ishida, Masayasu Ishikawa, Michael Jochimsen, Eric LeVine, Ambrose Li, Håkon Wium Lie, Chris Lilley, Ken Lunde, Myles Maxfield, Nat McCully, IM Mincheol, Shinyu Murakami, Paul Nelson, Chris Pratley, Xidorn Quan, Marcin Sawicki, Arnold Schrijver, Rahul Sonnad, Alan Stearns, Michel Suignard, Takao Suzuki, Frank Tang, Chris Thrasher, Etan Wexler, Chris Wilson, Masafumi Yabe and Steve Zilles.

Changes

Changes from the 12 December 2018 Working Draft

Changes from the 6 December 2018 Working Draft