CSS Text Level 3

Abstract

This CSS3 module defines properties for text manipulation and specifies their processing model. It covers line breaking, justification and alignment, white space handling, text decoration and text transformation.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This CSS module has been produced as a combined effort of the W3C Internationalization Activity, and the Style Activity and is maintained by the CSS Working Group. It also includes contributions made by participants in the XSL Working Group (members only).

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Feedback on this draft should be posted to the (archived) public mailing list www-style@w3.org (see instructions) with [css3-text] in the subject line. You are strongly encouraged to complain if you see something stupid in this draft. The editors will do their best to respond to all feedback.

If you have implemented properties from the May 2003 CSS3 Text CR please let us know so we can take that into account as we redraft the spec. You can post to www-style (public), post to the CSS WG mailing list (Member-restricted), or email fantasai directly (personal).

The following features are at risk and may be cut from the spec during its CR period:

• the 'text-outline' property
• the ''unrestricted'' value of 'text-wrap'
• the 'hanging-punctuation' property
• the 'text-trim' property
• audit draft and add more here

Table of Contents

Introduction

[document here]

Script Groups

Typographic behavior varies somewhat by language, but varies drastically by writing system. For convenience, CSS3 Text defines the following script groups, which combine typographically-similar scripts together.

block scripts

CJK (including Hangul and half-width kana) and by extension all "wide" characters. (See [[!UAX11]])

clustered scripts

South-East Asian scripts that have discrete units but do not use space between words (such as Thai, Lao, Khmer, Myanmar). This category also includes the Tibetan script.

discrete scripts

Scripts that use spaces or visible word-separating punctuation between words and have discrete, unconnected (in print) units within words, such as Latin, Greek, Ethiopic, Cyrillic, Hebrew.

cursive scripts

Arabic and similar cursive scripts.

connected scripts

Devanagari, Ogham, and other scripts that use spaces between words and baseline connectors within words. By extension this group also includes Gurmukhi, Tamil and any other Indic scripts whose typographic behavior is similar to Devanagari.

Provide an appendix using Unicode script names.

These definitions are used primarily in describing line-breaking and justification behavior.

Conformance

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification. All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [[!RFC2119]]

Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example", like this:

Informative notes begin with the word “Note” and are set apart from the normative text with class="note", like this:

Note, this is an informative note.

Conformance to CSS Text Level 3 is defined for three conformance classes:

style sheet

A CSS style sheet.

renderer

A UA that interprets the semantics of a style sheet and renders documents that use them.

authoring tool

A UA that writes a style sheet.

A style sheet is conformant to CSS Text Level 3 if all of its declarations that use properties defined in this module have values that are valid according to the generic CSS grammar and the individual grammars of each property as given in this module.

A renderer is conformant to CSS Text Level 3 if, in addition to interpreting the style sheet as defined by the appropriate specifications, it supports all the properties defined by CSS Text Level 3 by parsing them correctly and rendering the document accordingly. However, the inability of a UA to correctly render a document due to limitations of the device does not make the UA non-conformant. (For example, a UA is not required to render color on a monochrome monitor.)

An authoring tool is conformant to CSS Text Level 3 if it writes syntactically correct style sheets, according to the generic CSS grammar and the individual grammars of each property in this module.

Partial and Experimental Implementations

UAs must treat as invalid any properties or values they do not support. Experimental implementations of a feature should support only a vendor-prefixed syntax for the property/value.

Transforming Text

Transforming Text: the 'text-transform' property

This property transforms text for styling purposes. Values have the following meanings:

none

No effects.

capitalize

Puts the first character of each word in titlecase; other characters are unaffected.

uppercase

Puts all characters in uppercase.

lowercase

Puts all characters in lowercase.

fullwidth

Puts all characters in fullwidth form. If the character does not have a corresponding fullwidth form, it is left as is. This value is typically used to typeset Latin characters and digits like ideographic characters.

large-kana

Converts all small Kana characters to normal Kana. This value is typically used for ruby annotation text, where all small Kana should be drawn as large Kana.

Authors using this for ruby text may also want to use ''font-variant: ruby''. [[CSS3FONT]]

Although limited, the case mapping process has some language dependencies. Some well known examples are Turkish and Greek. If the content language is known then any such language-specific rules must be used.

The case mapping rules for the character repertoire specified by the Unicode Standard can be found on the Unicode Consortium Web site. [[!UNICODE]] Only characters belonging to bicameral scripts are affected.

The definition of fullwidth and halfwidth forms can be found on the Unicode consortium web site at [[!UAX11]].

The definition of "word" used for ''captilize'' 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).

Text transformation happens after white space processing. (This only matters when ''fullwidth'' transforms U+0020 space characters to U+3000.) This requirement may need to be relaxed during CR, so mark at-risk.

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

White Space Processing

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 for rendering: it has no effect on the underlying document data.

In the context of CSS, the document white space set is defined to be any space characters (Unicode value U+0020), tab characters (U+0009), and line feeds (U+000A).

However in the document source, segments can be delimited by carriage returns (U+000D), linefeeds (U+000A) or a combination (U+000D U+000A), or by some other mechanism, such as the SGML RECORD-START and RECORD-END tokens. In CSS, each such segment break is treated as a single line feed character (U+000A). If no segmentation rules are specified for the document language, each line feed (U+000A), carriage return (U+000D) and CRLF sequence (U+000D U+000A) in the text is considered a segment break. (This default rule also applies to generated content.)

Note that the document parser may have not only normalized segment breaks, but also collapsed other space characters or otherwise processed 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.

Control characters other than U+0009 (tab), U+000A (line feed), U+0020 (space), and U+202x (bidi formatting characters) are treated as characters to render in the same way as any normal character. Copied from CSS2.1 but this has got to be wrong.

White Space Collapsing: the 'white-space-collapsing' property

This section is still under discussion and may change in future drafts.

Rename to white-space-trim or white-space-adjust? white-space-collapsing has an 'ing' and is confusing with XSL

This property declares whether and how white space inside the element is collapsed. Values have the following meanings, which must be interpreted according to the white space processing rules:

collapse

This value directs user agents to collapse sequences of white space into a single character (or in some cases, no character).

preserve

This value prevents user agents from collapsing sequences of white space. Line feeds are preserved as forced line breaks.

preserve-breaks

This value collapses white space as for ''collapse'', but preserves line feeds as forced line breaks.

discard

This value directs user agents to "discard" all white space in the element.

trim-inner

This value directs UAs to discard all whitespace at the beginning of a block up to and including the last line feed before the first non-white-space character in the block as well as to discard all white space at the end of a block starting with the first line feed after the last non-white-space character in the block.

Tab Character Size: the 'tab-size' property

This property determines the width of the tab character (U+0009), in space characters (U+0020), when rendered. Only positive integers are allowed.

The White Space Processing Rules

For each inline (including anonymous inlines), white space characters are handled as follows, ignoring bidi formatting characters as if they were not there:

• If 'white-space-collapsing' is set to 'collapse' or 'preserve-breaks', white space characters are considered collapsible and are processed by performing the following steps:

  1. All spaces and tabs immediately preceding or following a line feed character are removed.
  2. If 'white-space-collapsing' is not 'preserve-breaks', line feed characters are transformed for rendering according to the line break transformation rules.
  3. Every tab (U+0009) is converted to a space (U+0020)
  4. Any space (U+0020) following another collapsible space (U+0020)—even a space before the inline—is removed. However, if removing this space would eliminate a line breaking opportunity in the text, that opportunity is still considered to exist.

• If 'white-space-collapsing' is set to 'preserve', any sequence of spaces (U+0020) unbroken by an element boundary is treated as a sequence of non-breaking spaces. However, a line breaking opportunity exists at the end of the sequence.

• If 'white-space-collapsing' is set to 'discard', the first white space character in every white space sequence is converted to a zero width non-joiner (U+200C) and the rest of the sequence is removed.

Then, the entire block is rendered. Inlines are laid out, taking bidi reordering into account, and wrapping as specified by the 'text-wrap' property.

As each line is laid out,

1. A sequence of collapsible spaces (U+0020) at the beginning of a line is removed.
2. Each tab (U+0009) is rendered as a horizontal shift that lines up the start edge of the next glyph with the next tab stop. Tab stops occur at points that are multiples of the width of a space (U+0020) rendered in the block's font from the block's starting content edge. How many spaces is given by the 'tab-size' property.
3. A sequence of collapsible spaces (U+0020) at the end of a line is removed.
4. If spaces (U+0020) or tabs (U+0009) at the end of a line are non-collapsible but have 'text-wrap' set to 'normal' or 'avoid' the UA may visually collapse them.

<ltr>A <rtl> B </rtl> C</ltr>

A  BC

Line Break Transformation Rules

When line feeds are collapsible, they are either transformed into a space (U+0020) or removed depending on the script context before and after the line break.

Note that the white space processing rules have already removed any tabs and spaces after the line feed before these checks take place.

• If the character immediately before or immediately after the line feed is the zero width space character (U+200B), then the line feed is removed.
• Otherwise, if the script context on one side of the line feed is Hangul, then the line feed is converted to a space (U+0020).
• Otherwise, if the East Asian Width property [[!UAX11]] of both the character before and after the line feed is F, W, or H (not A), then the line feed is removed.
• Otherwise, if 'text-autospace' property is set to add extra spaces for the combination of the character before the line feed and after, then the line break is removed.
• Otherwise, the line feed is converted to a space (U+0020).

Comments on how well this would work in practice would be very much appreciated, particularly from people who work with Thai and similar scripts.

Informative Summary of White Space Collapsing Effects

• Consecutive white space collapses into a single space.
• A sequence of newlines and other white space between two ideographic characters collapses into nothing unless there is a space before the first newline in the sequence.
• A zero width space within a white space sequence containing a newline causes the entire sequence of white space to collapse into a zero width space.

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

The 'white-space' property is a shorthand for the 'white-space-collapsing' and 'text-wrap' properties. Not all combinations are represented. Values have the following meanings:

normal

Sets 'white-space-collapsing' to 'collapse' and 'text-wrap' to 'normal'

pre

Sets 'white-space-collapsing' to 'preserve' and 'text-wrap' to 'none'

nowrap

Sets 'white-space-collapsing' to 'collapse' and 'text-wrap' to 'none'

pre-wrap

Sets 'white-space-collapsing' to 'preserve' and 'text-wrap' to 'normal'

pre-line

Sets 'white-space-collapsing' to 'preserve-breaks' and 'text-wrap' to 'normal'

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

Line Breaking and Word Boundaries

In most writing systems, in the absence of hyphenation a line break occurs only at word boundaries. Many writing systems use spaces or punctuation to explicitly separate words, and line break 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 break points in such texts.

In several other writing systems, (including Chinese, Japanese, Yi, and sometimes also Korean) a line break opportunity is based on character boundaries, not word boundaries. In these systems a line can break anywhere except between certain character combinations. Additionally the level of strictness in these restrictions can vary with the typesetting style.

CSS does not fully define where line breaking opportunities occur, however some controls are provided to distinguish common variations.

Further information on line breaking conventions can be found in [[JIS4051]] for Japanese, [[ZHMARK]] for Chinese, and [?] for Korean, and in [[!UAX14]] for all scripts in Unicode.

Any guidance for appropriate references here would be much appreciated.

Information on line-breaking in the absence of dictionaries: for Thai

Floated and absolutely-positioned elements do not introduce a line breaking opportunity. The line breaking behavior of a replaced element is equivalent to that of a Latin character.

It is not clear whether this section handles Southeast Asian scripts well. Additionally, some guidance should be provided on how to break or not break Southeast Asian in the absence of a dictionary.

Line Breaking Strictness: the 'line-break' property

This property specifies the strictness of line-breaking rules applied within an element: particularly how line-breaking interacts with punctuation. 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.

CSS distinguishes between three levels of strictness in the rules for implicit line breaking. The precise set of rules in effect for each level is up to the UA and should follow language conventions. However, this specification does recommend that:

• Following breaks be forbidden in ''strict'' line breaking and allowed in ''normal'':
  • breaks before Japanese small kana
  • breaks before the KATAKANA-HIRAGANA PROLONGED SOUND MARK (U+30FC)
  Additionally, if the language is known to be Chinese or Japanese, breaks before hyphens (U+2010, U+2013, U+301C, U+30A0) may be allowed in ''normal''.
• Following breaks be forbidden in ''normal'' and ''strict'' line breaking and allowed in ''loose'':
  • breaks before iteration marks (U+3005, U+303B, U+309D, U+309E, U+30FD, U+30FE)
  • breaks between inseparatable characters (U+2014, U+2025, U+2026, U+3033, U+3034, U+3035)
  If the language is known to be Chinese or Japanese, then additionally the following breaks may be allowed in ''loose'':
  • breaks before middle dots (U+003A, U+003B, U+30FB, U+FF1A, U+FF1B, U+FF65)
  • breaks before dividing punctuation marks (U+0021, U+003F, U+203C, U+2047, U+2048, U+2049, U+FF01, U+FF1F)
  • breaks before postfixes (U+0025, U+00A2, U+00B0, U+2030, U+2032, U+2033, U+2103, U+FF05, U+FFE0)
  • breaks after prefixes (U+0024, U+00A3, U+00A5, U+20AC, U+2116, U+FF04, U+FFE1, U+FFE5)

Word Breaking Rules: the 'word-break' property

This property specifies line break opportunities within words. Values have the following meanings:

normal

Break lines according to their usual rules.

break-all

Lines may break between any two grapheme clusters within words. Hyphenation is not applied. This option is used mostly in a context where the text is predominantly using CJK characters with few non-CJK excerpts and it is desired that the text be better distributed on each line.

keep-all

Block characters can no longer create implied break points. Otherwise this option is equivalent to ''normal''. This option is mostly used where the presence of word separator characters still creates line-breaking opportunities, as in Korean.

keep-words

Lines may not break within words, even in block scripts (which would require the use of a dictionary in languages such as Chinese and Japanese). This option is sometimes used in combination with start-aligned (unjustified) text. This value is likely to be dropped before CR unless there is interest from implementers.

When shaping scripts such as Arabic are allowed to break within words due to ''break-all'', the characters must still be shaped as if the word were not broken.

Hyphenation

Hyphenation allows the controlled splitting of words to improve the layout of paragraphs. CSS3 Text does not define the exact rules for hyphenation, but defines six properties and an at-rule that influence hyphenation.

Whether hyphenation is applied can controlled with the 'hyphens' property.

Hyphenation Control: the 'hyphens' property

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

none

Words are not broken at line breaks, even if characters inside the word suggest line break points.

manual

Words are only broken at line breaks where there are characters inside the word that suggest line break opportunities. Characters can be explicit or conditional.

In Unicode, U+00AD is a conditional "soft hyphen" and U+2010 is an explicit hyphen. Unicode Standard Annex #14 describes the role of soft hyphens in Unicode line breaking. [[!UAX14]]

In HTML, ­ represents the soft hyphen character which suggests a line break opportunity.

ex­ample

auto

Words can be broken at appropriate hyphenation points either as determined by hyphenation characters inside the word or as determined automatically by a language-appropriate hyphenation resource (such as those provided via ''@hyphenation-resource''). Explicit hyphenation characters inside a word take priority over automatic resources when determining hyphenation points within the word.

all

All possible hyphenation points, as would be determined for ''auto'', are marked. The visual appearance of the mark is UA-dependent. This value is intended for debugging. Do we really need this value?

Correct automatic hyphenation requires a hyphenation resource appropriate to the language of the text being broken. The UA is therefore only required to automatically hyphenate text for which the author has declared a language (e.g. via HTML lang or XML xml:lang) and for which it has an appropriate hyphenation resource.

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.

Hyphens: the 'hyphenate-character' property

This property specifies strings that are shown between parts of hyphenated words. The 'auto' value means that the user agent should find an appropriate value. If one string is specified, it appears at the end of lines. If two strings are specified, the second string appears at the beginning of lines.

Is the use of hyphenate characters at the beginning of lines common enough for this to be part of the specification?

article { hyphenate-character: "\2010" }

Hyphenation Size Limit: the 'hyphenate-limit-zone' property

Is 'hyphenate-limit-zone' a good name? Comments/suggestions?

This property specifies the maximum amount of unfilled space (before justification) that may be left in the line box before hyphenation is triggered to pull part of a word from the next line back up into the current line.

Should percentages be relative to the line box or the block? (Difference occurs in presence of floats. Making it relative to the line box means the hyphenation zone adapts to how much space there is on the line.)

Hyphenation Character Limits: the 'hyphenate-limit-before' and 'hyphenate-limit-after' properties

This property specifies the minimum number of characters in a hyphenated word before the hyphenation character. The ''auto'' value means that the UA chooses a value that adapts to the current layout.

Unless the UA is able to calculate a better value, it is suggested that ''auto'' means 2.

This property specifies the minimum number of characters in a hyphenated word after the hyphenation character. The ''auto'' value means that the UA chooses a value that adapts to the current layout.

Unless the UA is able to calculate a better value, it is suggested that ''auto'' means 2.

Hyphenation Line Limits: the 'hyphenate-limit-lines' and 'hyphenate-limit-last' properties

This property indicates the maximum number of successive hyphenated lines in an element. In some cases, user agents may not be able to honor the specified value. The ''no-limit'' value means that there is no limit.

This property indicates hyphenation behavior at the end of elements, column, pages and spreads. A spread is a set of two pages that are visible to the reader at the same time. Values are:

''none''

No restrictions imposed.

''always''

The last full line of the element, or the last line before any column, page, or spread break inside the element should not be hyphenated.

''column''

The last line before any column, page, or spread break inside the element should not be hyphenated.

''page''

The last line before page or spread break inside the element should not be hyphenated.

''spread''

The last line before any spread break inside the element should not be hyphenated.

p { hyphenate-limit-last: always }
div.chapter {  hyphenate-limit-last: spread }

This is just a
simple example
to show Antarc-
tica.
      

This is just a
simple example
to        show 
Antarctica.
      
    

Hyphenation Resources

@hyphenate-resource {
  /* English */
  en:    url(en-GB.hy);
  en-US: url(en-US.hy);
  en-x-hixie:    url(hixie.hy), local, url(en-GB.hy);
  en-US-x-hixie: url(hixie.hy), local, url(en-US.hy);
  /* français */
  fr:    url(fr.hy);
}
    

The 'hyphenate-resource' property

This property specifies a comma-separated list of external resources that can help the UA determine hyphenation points. If more than one resource is specified, the UA should consult each resource – in turn, from the beginning – until it finds one that is able to determine hyphenation points in a word. The 'none' value indicates that no external resources are available. In any case, the UA can also use local resources not listed on this property.

:lang(dk) { hyphenate-resource: url("hyph_da_DK.dic"), url("hyph_da_NO.dic") }
      

UAs are not required to support this property.

Use a format specifier, like @font-face? What is the format?

Text Wrapping

Text wrapping is controlled by the 'text-wrap' and 'word-wrap' properties:

Text Wrap Settings: the 'text-wrap' property

This property specifies the mode for text wrapping. Possible values:

normal

Lines may break at allowed break points, as determined by the line-breaking rules in effect. Line breaking behavior defined for the WJ, ZW, and GL line-breaking classes in [[!UAX14]] must be honored.

none

Lines may not break; text that does not fit within the block container overflows it.

unrestricted

Lines may break between any two grapheme clusters. Line-breaking restrictions have no effect and hyphenation does not take place. Character shaping is performed on each side of the break as if the break had not occurred. This value is for terminal-style dumb line breaking. But has no use cases.

avoid

Line breaking is suppressed within the element: the UA may only break within the element if there are no other valid break points in the line. If the text breaks, line-breaking restrictions are honored as for 'normal'.

Regardless of the 'text-wrap' value, lines always break at forced breaks: for all values, line-breaking behavior defined for the BK, CR, LF, CM NL, and SG line breaking classes in [[!UAX14]] must be honored.

When 'text-wrap' is set to 'normal' or 'avoid', UAs that allow breaks at punctuation other than spaces should prioritize breakpoints. For example, if breaks after slashes have a lower priority than spaces, the sequence "check /etc" will never break between the '/' and the 'e'. The UA may use the width of the containing block, the text's language, and other factors in assigning priorities. As long as care is taken to avoid such awkward breaks, allowing breaks at appropriate punctuation other than spaces is recommended, as it results in more even-looking margins, particularly in narrow measures.

footer { text-wrap: avoid; /* inherits to all descendants */ }
      

<footer>
  <venue>27th Internationalization and Unicode Conference</venue>
  &#8226; <date>April 7, 2005</date> &#8226;
  <place>Berlin, Germany</place>
</footer>
      

27th Internationalization and Unicode Conference •
April 7, 2005 • Berlin, Germany
      

27th Internationalization and Unicode
Conference • April 7, 2005 •
Berlin, Germany
      

27th Internationalization and Unicode Conference • April
7, 2005 • Berlin, Germany
      

Emergency Wrapping: the 'word-wrap' property

This property specifies whether the UA may break within a word to prevent overflow when an otherwise-unbreakable string is too long to fit within the line box. It only has an effect when 'text-wrap' is either 'normal' or 'avoid'. 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'' and the various hyphenation limit properties may be ignored if there are no otherwise-acceptable break points in the line.

break-word

An unbreakable "word" 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 together stay as one unit.

Should there be a ''hyphenate'' value, that turns on hyphenation only for emergency breaking? (This would give better results than ''break-word''.)

Should there be a ''none'' value, that prevents the relaxation of 'word-break' and hyphenation limit restrictions?

Alignment and Justification

Text Alignment: the 'text-align' property

This property describes how inline contents of a block are horizontally aligned if the contents do not completely fill the line box. Values have the following meanings:

start

The inline contents are aligned to the start edge of the line box.

end

The inline contents are aligned to the end edge of the line box.

left

The inline contents are aligned to the left edge of the line box. In vertical text, 'left' aligns to the edge of the line box that would be the start edge for left-to-right text.

right

The inline contents are aligned to the right edge of the line box. In vertical text, 'right' aligns to the edge of the line box that would be the end edge for left-to-right text.

center

The inline contents are centered within the line box.

justify

The text is justified according to the method specified by the 'text-justify' property.

<string>

The string must be a single character; otherwise the declaration must be ignored. When applied to a table cell, specifies the alignment character around which the cell's contents will align. See below for further details.

match-parent

This value behaves the same as 'inherit' except that an inherited 'start' or 'end' keyword is calculated against its parent's 'direction' value and results in a computed value of either 'left' or 'right'.

A block of text is a stack of line boxes. In the case of 'start', 'end', 'left', 'right' and 'center', 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 in addition to shifting their positions. (See also 'text-justify', 'letter-spacing', and 'word-spacing'.) If an element's white space is set to be 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 expansion 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.

Details on Character-based Alignment in a Table Column

When multiple cells in a column have an alignment character specified, the alignment character of each such cell in the column is centered along a single column-parallel axis and the rest of the text in the column shifted accordingly. (Note that the strings do not have to be the same for each cell, although they usually are.)

If the alignment character appears more than once in the text, the first instance is used for alignment. If the alignment character does not appear in a cell at all, the string is aligned as if the alignment character had been inserted at the end of its contents.

Character-based alignment occurs before table cell width computation so that auto width computations can leave enough space for alignment. Whether column-spanning cells participate in the alignment prior to or after width computation is undefined. If width constraints on the cell contents prevent full alignment throughout the column, the resulting alignment is undefined.

A keyword value may be specified in conjunction with the <string> value; if it is not given, it defaults to ''right''. This value is used:

• when character-based alignment is applied to boxes that are not table cells.
• when the text wraps to multiple lines.
• when the column is wide enough that the character alignment alone does not determine the positions of its character-aligned contents. In this case the keyword alignment of the first cell in the column with a specified alignment character is used to slide the position of the character-aligned contents to match the keyword alignment insofar as possible without changing the width of the column. For ''center'', the UA may center the aligned contents using its extremes, center the alignment axis itself (insofar as possible), or optically center the aligned contents some other way (such as by taking a weighted average of the extent of the cells' contents to either side of the axis).
• when a character-aligned cell spans more than one column. In this case the keyword alignment value is used to determine which column's axis to align with: the leftmost column for ''left'', the rightmost column for ''right'' and ''center'', the startmost column for ''start'', the endmost column for ''end''.

TD { text-align: "." center }

<TABLE>
<COL width="40">
<TR> <TH>Long distance calls
<TR> <TD> $1.30
<TR> <TD> $2.50
<TR> <TD> $10.80
<TR> <TD> $111.01
<TR> <TD> $85.
<TR> <TD> N/A
<TR> <TD> $.05
<TR> <TD> $.06
</TABLE>

+---------------------+
| Long distance calls |
+---------------------+
|        $11.30       |
|        $22.50       |
|         $0.80       |
|    $200567.01       |
|        $85.         |
|        N/A          |
|          $.05       |
|          $.06       |
+---------------------+

Right alignment is used by default for character-based alignment because numbering systems are almost all left-to-right even in right-to-left writing systems, and the primary use case of character-based alignment is for numerical alignment.

First Line Alignment: the 'text-align-first' property

This property describes how the first line of a block or a line right after a forced line break is aligned. Values have the following meanings:

''auto''

Use the alignment given by 'text-align' (or by 'text-align-last' if that applies instead).

''start''

The inline contents are aligned to the start edge of the line box. (This overrides 'text-align-last' if both apply to this line.)

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

This property describes how the last line of a block or a line right before a forced line break is aligned. ''auto'' is equivalent to the value of the 'text-align' property except when 'text-align' is set to ''justify'', in which case it is ''justify'' when 'text-justify' is ''distribute'' and ''start'' otherwise. All other values have the same meanings as in 'text-align'.

Justification Method: the 'text-justify' property

This property selects the justification method used when a line's alignment is set to ''justify''. (See 'text-align'.) The property applies to block containers, but the UA may (but is not required to) also support it on inline elements. It takes the following values:

auto

The UA determines the justification algorithm to follow, based on a balance between performance and adequate presentation quality.

One possible algorithm is to determine the behavior based on the language of the paragraph: the UA can then choose appropriate value for the language, like ''inter-ideograph'' for CJK, or ''inter-word'' for English. Another possibility is to use a justification method that is a universal compromise for all scripts, e.g. the ''inter-cluster'' method with block scripts raised to first priority.

none

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

inter-word

Justification primarily changes spacing at word separators. This value is typically used for languages that separate words using spaces, like English or (sometimes) Korean.

inter-ideograph

Justification primarily changes spacing at word separators and at inter-graphemic boundaries in scripts that use no word spaces. This value is typically used for CJK languages.

inter-cluster

Justification primarily changes spacing at word separators and at grapheme cluster boundaries in clustered scripts. This value is typically used for Southeast Asian scripts such as Thai.

distribute

Justification primarily changes spacing both at word separators and at grapheme cluster boundaries in all scripts except those in the connected and cursive groups. This value is sometimes used in e.g. Japanese.

kashida

Justification primarily stretches cursive scripts through the use of kashida or other calligraphic elongation.

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. If the 'letter-spacing' and 'word-spacing' property values allow it, the user agent may also distribute negative space, putting more content on the line than would otherwise fit under normal spacing conditions. The exact justification algorithm is UA-dependent; however, CSS provides some general guidelines which should be followed when any justification method other than 'auto' is specified.

CSS defines expansion opportunities as points where the justification algorithm may alter spacing within the text. These expansion opportunities fall into priority levels as defined by the justification method. Within a line, higher priority expansion opportunities should be expanded or compressed to their limits before lower priority expansion opportunities are adjusted. (Expansion and compression limits are given by the letter-spacing and word-spacing properties.)

How any remaining space is distributed once all expansion opportunities reach their limits is up to the UA. 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'' if 'text-justify' is ''distribute'' and as ''start'' otherwise.)

The expansion opportunity priorities for values of 'text-justify' are given in the table below. Space must be distributed evenly among all types of expansion opportunities in a given prioritization group, but may vary within a line due to changes in the font or letter-spacing and word-spacing values. Since justification behavior varies by writing system, expansion opportunities are organized by script group. The different types of expansion opportunities are defined as follows:

spaces

An expansion opportunity exists at spaces and other word separators. Expand as for 'word-spacing'.

block

clustered

discrete

An expansion opportunity exists between two grapheme clusters when at least one of them belongs to the affected script group and the spacing that point has not already been altered at a higher priority.

cursive

Words may be expanded through kashida elongation or other cursive expansion processes. Kashida may be applied in discrete units or continuously, and the prioritization of kashida points is UA-dependent: for example, the UA may apply more at the end of the line. The UA should not apply kashida to fonts for which it is inappropriate. It may instead rely on other justification methods that lengthen or shorten Arabic segments (e.g. by substituting in swash forms or optional ligatures). Because elongation rules depend on the typeface style, the UA should rely on on the font whenever possible rather than inserting kashida based on a font-independent ruleset. The UA should limit elongation so that, e.g. in multi-script lines a short stretch of Arabic will not be forced to soak up too much of the extra space by itself. If the UA does not support cursive elongation, then no expansion points exist between grapheme clusters of these scripts.

punctuation

An expansion opportunity exists between a pair of characters from the Unicode symbols (S*) and punctuation (P*) classes and at enabled autospace points. The default justification priority of these points depends on the justification method as defined below; however there may be additional rules controlling their justification behavior due to typographic tradition. For example, there are traditionally no expansion opportunities between consecutive EM DASH U+2014, HORIZONTAL BA U+2015, HORIZONTAL ELLIPSIS U+2026, or TWO DOT LEADER U+2025 characters [[JLREQ]]. The UA may introduce additional levels of priority to handle expansion opportunities involving punctuation.

connected

No expansion opportunities occur between pairs of connected script grapheme clusters. Is this correct?

The ''auto'' column defined above is informative.

The UA may enable or break optional ligatures or use other font features such as alternate glyphs to help justify the text under any method. This behavior is not defined by CSS.

Spacing

The next two properties refer to the <spacing-limit> value type, which is defined as follows:

<spacing-limit>

[ normal | <length> | <percentage> ]

normal

Specifies the normal optimum/minimum/maximum spacing, as defined by the current font and/or the user agent. Normal spacing should be percentage-based. Normal minimum and maximum spacing must be based on the optimum spacing so that the minimum and maximum limits increase and decrease with changes to the optimum spacing. Normal minimum and maximum spacing may also vary according to some measure of the amount of text on a line (e.g. block width divided by font size): larger measures can accommodate tighter spacing constraints. Normal optimum/minimum/maximum spacing may also vary based on the value of the 'text-justify' property, the element's language, and other factors. Normal minimum, maximum, and optimal spacing between a pair of connected or cursive grapheme clusters is always zero.

<length> or <percentage>

Specifies extra spacing in addition to the normal spacing. Percentages are with respect to the width of the affected character. Values may be negative, but there may be implementation-dependent limits.

Word Spacing: the 'word-spacing' property

This property specifies the minimum, maximum, and optimal spacing between words. If only one value is specified, then it represents the optimal spacing and the minimum and maximum are both 'normal'. If two values are specified, then the first represents both the optimal spacing and the minimum spacing, and the second represents the maximum spacing. If three values are specified, they represent the optimum, minimum, and maximum respectively.

If the value of the optimum or maximum spacing is less than the value of the minimum spacing, then its used value is the minimum spacing. If the optimum spacing is greater than the maximum spacing then its used value is the maximum spacing. (This substitution occurs after inheritance.)

In the absence of justification the optimal spacing must be used. The text justification process may alter the spacing from its optimum (see the 'text-justify' property, above) but must not violate the minimum spacing limit and should also avoid exceeding the maximum.

Spacing is applied to each word-separator character left in the text after the white space processing rules have been applied and should be applied half on each side of the character. This is correct for Ethiopian and doesn't matter for invisible spaces, but is it correct for Tibetan? Most publications seem to add space after the tsek mark during justification. Word-separator characters include 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 Tibetan tsek (U+0F0B, U+0F0C). Is this list correct? If there are no word-separator characters, or if the 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. General punctuation and fixed-width spaces (such as U+3000 and U+2000 through U+200A) are not considered word-separators.

Tracking: the 'letter-spacing' property

This property specifies the minimum, maximum, and optimal spacing between grapheme clusters. If only one value is specified, then it represents all three values. If two values are specified, then the first represents both the optimal spacing and the minimum spacing, and the second represents the maximum spacing. If three values are specified, they represent the optimum, minimum, and maximum respectively.

If the value of the optimum or maximum spacing is less than the value of the minimum spacing, then its used value is the minimum spacing. If the optimum spacing is greater than the maximum spacing then its used value is the maximum spacing. (This substitution occurs after inheritance.)

In the absence of justification the optimal spacing must be used. The text justification process may alter the spacing from its optimum (see the 'text-justify' property, above) but must not violate the minimum spacing limit and should also avoid exceeding the maximum. Letter-spacing is applied in addition to any word-spacing. 'normal' optimum letter-spacing is typically zero.

A grapheme cluster is what a language user considers to be a character or a basic unit of the script. The term is described in detail in the Unicode Technical Report: Text Boundaries [[!UAX29]]. This specification uses the extended grapheme cluster definition in [[!UAX29]] (not the legacy grapheme cluster definition). The UA may further tailor the definition as allowed by Unicode.

Letter-spacing must not be applied at the beginning or at the end of a line. At element boundaries, the letter spacing is given by and rendered within the innermost element that contains the boundary.

<P>a<LS>b<Z>cd</Z><Y>ef</Y></LS>g</P>

LS { letter-spacing: 1em; }
Z { letter-spacing: 0.3em; }
Y { letter-spacing: 0.4em; }

a[0]b[1em]c[0.3em]d[1em]e[0.4em]f[0]g

UAs may apply letter-spacing to cursive scripts. In this case, UAs should extend the space between disjoint graphemes as specified above and extend the visible connection between cursively connected graphemes by the same amount (rather than leaving a gap). The UA may use glyph substitution or other font capabilities to spread out the letters. If the UA cannot expand a cursive script without breaking the cursive connections, it should not apply letter-spacing between grapheme clusters of that script at all.

When the resulting space between two characters is not the same as the default space, user agents should not use optional ligatures.

Fullwidth Kerning: the 'text-trim' property

        Syntax is derived as a shorthand of the following theoretical
        properties (defaults given first):

           text-trim-start:      keep-start | force-start
           text-trim-end:        allow-end | force-end | keep-end | keep-fullstop
           text-trim-adjacent:   force-adjacent | keep-adjacent
           text-trim-kana:       ...
           text-trim-justify:    justify | no-justify

        Filtering out the default values (and ignoring trim-kana),
        we get the following shorthand:
           text-trim: normal |
                      force-start ||
                      [ force-end | keep-end | keep-fullstop] ||
                      keep-adjacent ||
                      no-justify
    

This property determines whether or not a fullwidth punctuation character should be trimmed (kerned). Values are defined as follows:

normal

Trim (kern) the blank half of fullwidth closing punctuation at the end of each line if it does not otherwise fit prior to justification.

force-start

Trim (kern) the blank half of fullwidth opening punctuation at the beginning of each line.

keep-end

Do not trim the blank half of fullwidth opening punctuation at the end of each line.

force-end

Trim (kern) the blank half of fullwidth closing punctuation at the end of each line.

no-justify

The blank portions of fullwidth punctuation must not be trimmed during the justification process. (If this value is not specified, the justification process may trim the blank portions of fullwidth punctuation glyphs.) An example of compression rules is given for Japanese in 3.8 Line Adjustment in [[JLREQ]].

Figure out proper interaction with text-align: end. Does allow-end behavior make sense? Do we want allow-start instead?

In all cases, the UA must trim (kern) the blank half of fullwidth opening punctuation if its previous adjacent character is a fullwidth opening punctuation, fullwidth middle dot punctuation, fullwidth closing punctuation, or ideographic space (U+3000). It must also trim (kern) the blank half of fullwidth closing punctuation if its next adjacent character is a fullwidth closing punctuation, fullwidth middle dot punctuation, or ideographic space (U+3000).

In the context of this property the following definitions apply:

classes and Unicode code point should be reviewed.

fullwidth opening punctuation

Includes any opening punctuation character (Unicode category Ps) that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F) or is categorized as East Asian Fullwidth (F) by [[!UAX11]]. Also includes LEFT SINGLE QUOTATION MARK (U+2018) and LEFT DOUBLE QUOTATION MARK (U+201C). When trimmed, the left (for horizontal text) or top (for vertical text) half is kerned.

fullwidth closing punctuation

Includes any closing punctuation character (Unicode category Pe) that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F) or is categorized as East Asian Fullwidth (F) by [[!UAX11]]. Also includes RIGHT SINGLE QUOTATION MARK (U+2019) and RIGHT DOUBLE QUOTATION MARK (U+201D). May also include fullwidth colon punctuation and/or fullwidth dot punctuation (see below). When trimmed, the right (for horizontal text) or bottom (for vertical text) half is kerned.

fullwidth middle dot punctuation

Includes MIDDLE DOT (U+00B7), HYPHENATION POINT (U+2027), and KATAKANA MIDDLE DOT (U+30FB). May also include fullwidth colon punctuation and/or fullwidth dot punctuation (see below).

fullwidth colon punctuation

Includes FULLWIDTH COLON (U+FF1A) and FULLWIDTH SEMICOLON (U+FF1B).

fullwidth dot punctuation

Includes IDEOGRAPHIC COMMA (U+3001), IDEOGRAPHIC FULL STOP (U+3002), FULLWIDTH COMMA (U+FF0C), FULLWIDTH FULL STOP (U+FF0E).

Fullwidth opening and closing punctuation must not be trimmed if the glyph is not actually fullwidth. This includes the case where the glyph is not fullwidth as a result of the kerning in the font. A fullwidth glyph is one that has the same advance width as a typical Han character in the same font.

Whether fullwidth colon punctuation and fullwidth dot punctuation should be considered fullwidth closing punctuation or fullwidth middle dot punctuation depends on where in the glyph's box the punctuation is drawn. If the punctuation is centered, then it should be considered middle dot punctuation. If the punctuation is drawn to one side (left in horizontal text, top in vertical text) and the other half is therefore blank then the punctuation should be considered closing punctuation and trimmed accordingly.

The UA must classify fullwidth colon punctuation and fullwidth dot punctuation under either the fullwidth closing punctuation category or the fullwidth middle dot punctuation category as appropriate. The UA may rely on language conventions and the layout orientation (horizontal vs. vertical), and/or font information to determine this categorization. The UA may also add additional characters to any category as appropriate.

Adding space: the 'text-autospace' property

When a run of non-ideographic or numeric characters appears inside of ideographic text, a certain amount of space is often preferred on both sides of the non-ideographic text to separate it from the surrounding ideographic glyphs. This property controls the creation of that space when rendering the text. That added width does not correspond to the insertion of additional space characters, but instead to the width increment of existing glyphs.

(A commonly used algorithm for determining this behavior is specified in JIS X-4051 [[JIS4051]].)

This property is additive with the 'word-spacing' and 'letter-spacing' [[!CSS21]] properties. That is, the amount of spacing contributed by the 'letter-spacing' setting (if any) is added to the spacing created by 'text-autospace'. The same applies to 'word-spacing'.

The space added can be compressed or expanded during the justification process as specified in the 'text-justify' property.

This property applies only to the same inline element context, and can apply across elements if in the same inline element context.

Values have the following meanings:

none

No extra space is created.

ideograph-numeric

Creates 1/4em extra spacing between runs of ideographic letters and non-ideographic numeric glyphs.

ideograph-alpha

Creates 1/4em extra spacing between runs of ideographic letters and non-ideographic letters, such as Latin-based, Cyrillic, Greek, Arabic or Hebrew.

punctuation

Creates extra non-breaking spacing around punctuation as required by language-specific typographic conventions. For example, if the element's content language is French, narrow no-break space (U+202F) and no-break space (U+00A0) should be inserted where required by French typographic guidelines.

It was requested to add a value for doubling the space after periods.

At element boundaries, the font size of the extra spacing is given by and rendered within the innermost element that contains the boundary.

In the context of this property the following definitions apply:

Reviews and feedbacks to the classes/code points are appreciated.

Ideographic letters

• All characters in the range of U+3041 to U+30FF, except that belongs to Unicode Punctuation [P*] category.
• CJK Strokes (U+31C0 to U+31EF).
• Katakana Phonetic Extensions (U+31F0 to U+31FF).
• All characters that belongs to Han Unicode Script Property [[!UAX24]].

Non-ideographic numerals

• All characters that belongs to Unicode Number, Decimal Digit [Nd] category.
• Except any of the following conditions are met:
  • Is categorized as East Asian Fullwidth (F) by [[!UAX11]].
  • Is upright in vertical text flow using the 'text-orientation' property or the 'text-combine' property.

Non-ideographic letters

• All characters that belongs to Unicode Letters [L*] and Mark [M*] category.
• Except any of the following conditions are met:
  • Is defined as Ideographic letters.
  • Is categorized as East Asian Fullwidth (F) by [[!UAX11]].
  • Is upright in vertical text flow using the 'text-orientation' property or the 'text-combine' property.

Edge Effects

First Line Indentation: the 'text-indent' property

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. Unless otherwise specified via the ''each-line'' and/or ''hanging'' keywords, only lines that are the first formatted line of an element. For example, the first line of an anonymous block box is only affected if it is the first child of its parent element.

Values have the following meanings:

<length>

Gives the amount of the indent as an absolute length.

<percentage>

Gives the amount of the indent as a percentage of the containing block's logical width.

each-line

Indentation affects the first line of the block container as well as each line after a forced line break, but does not affect lines after a text wrap break.

hanging

Inverts which lines are affected.

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

Note that 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 Punctuation: the 'hanging-punctuation' property

This property determines whether a punctuation mark, if one is present, may be placed outside the line box (or in the indent) at the start or at the end of a full line of text. Such hanging punctuation is not considered when measuring the line's contents for indentation, alignment, or justification. Values have the following meanings:

first

Punctuation (specifically, opening brackets and quotes) may hang outside the start edge of the first line. This applies to all characters in the Unicode categories Ps, Pf, Pi.

last

Punctuation (specifically, closing brackets and quotes) may hang outside the start edge of the first line. This applies to all characters in the Unicode categories Pe, Pf, and Pi. This value appears to have no use cases. If none are submitted, it will be dropped in the next draft.

allow-end

Punctuation (specifically, stops and commas) may hang outside the end edge of any line if the punctuation does not otherwise fit prior to justification.

force-end

Punctuation (specifically, stops and commas) may hang outside the end edge of any 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.

Should other characters be included?

The CSS Working Group would appreciate if such UAs would inform the working group of such additional characters.

In all cases only one punctuation character may hang outside the edge of the line. Furthermore, start and end borders or padding on an inline element are never allowed to hang.

Note that if there is not sufficient padding on the block container, hanging punctuation may trigger overflow.

Text Decoration

Line Decoration: Underline, Overline, and Strike-Through

Sync this against CSS2.1.

The following properties describe line decorations that are added to the content of an element. When specified on an inline element, such decoration affects all the boxes generated by that element; for all other elements, the decorations are propagated to an anonymous inline box that wraps all the in-flow inline children of the element, and to any block-level in-flow descendants. They are not, however, further propagated to floating and absolutely positioned descendants, nor to the contents of inline-table and inline-block descendants. The value of the text-decoration-line property on descendant elements therefore cannot have any effect on the decoration of the ancestor; to skip descendants, use the text-decoration-skip property.

By default underlines, overlines, and line-throughs are applied only to text (including white space, letter spacing, and word spacing): margins, borders, and padding are skipped. Elements containing no text, such as images, are likewise not decorated. The text-decoration-skip property can be used to modify this behavior, for example allowing inline replaced elements to be underlined or requiring that white space be skipped.

The UA should place the start and end of the line inwards from the content edge of the decorating element so that, e.g. two underlined elements side-by-side do not appear to have a single underline. (This is important in Chinese, where underlining is a form of punctuation.)

In determining the position and thickness of text decoration lines, user agents may consider the font sizes and dominant baselines of descendants, but for a given element's decoration must use the same baseline and thickness on each line. Relatively positioning a descendant moves all text decorations affecting it along with the descendant's text; it does not affect calculation of the decoration's initial position on that line. The color and line style of decorations must remain the same on all decorations applied by a given element, even if descendant elements have different color or line style values.

   blockquote { text-decoration: underline; color: blue; }
   em { display: block; }
   cite { color: fuchsia; }

   <blockquote>
    <p>
     <span>
      Help, help!
      <em> I am under a hat! </em>

      <cite> —GwieF </cite>
     </span>
    </p>
   </blockquote>

Text Decoration Lines: the 'text-decoration-line' property

Specifies what line decorations, if any, are added to the element. Values have the following meanings:

none

Produces no text decoration.

underline

Each line of text is underlined.

overline

Each line of text has a line above it (i.e. on the opposite side from an underline).

line-through

Each line of text has a line through the middle.

Text Decoration Color: the 'text-decoration-color' property

This property specifies the color of text decoration (underlines overlines, and line-throughs) set on the element with text-decoration-line.

Text Decoration Style: the 'text-decoration-style' property

This property specifies the style of the line(s) drawn for text decoration specified on the element. Values have the same meaning as for the border-style properties [[!CSS3BG]].

Text Decoration Shorthand: the 'text-decoration' property

This property is a shorthand for setting text-decoration-line, text-decoration-color, and text-decoration-style in one declaration. Omitted values are set to their initial values. A text-decoration declaration that omits both the text-decoration-color and text-decoration-style values is backwards-compatible with CSS Levels 1 and 2.

If the blink keyword is specified the text blinks (alternates between visible and invisible). Conforming user agents may simply not blink the text. Note that not blinking the text is one technique to satisfy checkpoint 3.3 of WAI-UAAG.

:link {
    color: blue;
    text-decoration: underline;
    text-decoration: navy dotted underline; /* Ignored in CSS1/CSS2 UAs */
}

Text Decoration Line Continuity: the 'text-decoration-skip' property

This property specifies what parts of the element's content any text decoration affecting the element must skip over. It controls all text decoration lines drawn by the element and also any text decoration lines drawn by its ancestors. Values have the following meanings:

none

Skip nothing: text-decoration is drawn for all text content and for inline replaced elements.

objects

Skip this element if it is an atomic inline (such as an image or inline-block).

spaces

Skip white space: this includes regular spaces (U+0020) and tabs (U+0009), as well as nbsp (U+00A0), ideographic space (U+3000), all fixed width spaces (such as U+2000–U+200A, U+202F and U+205F), and any adjacent letter-spacing or word-spacing.

ink

Skip over where glyphs are drawn: interrupt the decoration line to let text show through where the text decoration would otherwise cross over a glyph. The UA may also skip a small distance to either side of the glyph outline.

all

Skip over all content in this element.

Do we need a value that doesn't skip margins and padding?

Note that this property inherits and that descendant elements can have a different setting. Therefore a child of an element with text-decoration-skip: all can cause its grandparent's underline to be drawn by specifying text-decoration-skip: none.

Text Underline Position: the 'text-underline-position' property

This property sets the position of an underline specified on the same element: it does not affect underlines specified by ancestor elements. Values have the following meanings:

''auto''

The user agent may use any algorithm to determine the underline's position; however in vertical typographic mode, if the language of the element is set to Japanese or Korean (matches :lang(ja) or :lang(ko)) the underline must be drawn on the right side of the text as described for ''below right''.

It is suggested that the underline position be ''alphabetic'' unless it crosses either subscripted (or otherwise lowered) text, or it affects characters from Asian scripts such as Han or Tibetan, for which an alphabetic underline is too high: in such cases, aligning to the em box edge as described for ''below left'' is more appropriate.

''alphabetic''

The underline is aligned with the alphabetic baseline. In this case the underline is likely to cross some descenders.

''below left''

The underline is aligned with the under edge of the element's content box. In this case the underline usually does not cross the descenders. (This is sometimes called "accounting" underline.) If the underline affects descendants with a lower content edge, the user agent should shift the underline down further to the lowest underlined content box edge. The user agent may ignore elements with ''vertical-align'' values given as lengths, percentages, ''top'', or ''bottom'' when making this adjustment. (Note that images that are not affected by the underline per 'text-decoration-skip' will not affect the position of the underline.)

''below right''

In horizontal typographic mode, this value is equivalent to ''below left''. In vertical typographic mode, the underline is aligned as for ''below left'', except it is aligned to the right edge of the text. If this causes the underline to be drawn on the "over" side of the text, then an overline also switches sides and is drawn on the "under" side.

Emphasis Marks

East Asian documents traditionally use small symbols next to each glyph to emphasize a run of text. For example:

Emphasis Mark Style: the 'text-emphasis-style' property

This property applies emphasis marks to the element's text. Values have the following meanings:

none

No emphasis marks.

filled

The shape is filled with solid color.

open

The shape is hollow.

dot

Draw small circles as marks. The filled dot is U+2022 '•', and the open dot is U+25E6 '◦'.

circle

Draw large circles as marks. The filled circle is U+25CF '●', and the open circle is U+25CB '○'.

double-circle

Draw double circles as marks. The filled double-circle is U+25C9 '◉', and the open double-circle is U+25CE '◎'.

triangle

Draw triangles as marks. The filled triangle is U+25B2 '▲', and the open triangle is U+25B3 '△'.

sesame

Draw sesames as marks. The filled sesame is U+FE45 '﹅', and the open sesame is U+FE46 '﹆'.

<string>

Draw the given string as marks. Authors should not specify more than one grapheme cluster in <string>. The UA may truncate or ignore strings consisting of more than one grapheme cluster.

If a shape keyword is specified but neither of ''filled'' nor ''open'' is specified, ''filled'' is assumed. If only ''filled'' or ''open'' is specified, the shape keyword computes to ''circle'' in horizontal writing mode and ''sesame'' in vertical writing mode.

The marks should be drawn using the element's font settings with its size scaled down to 50%. However, not all fonts have all these glyphs, and some fonts use inappropriate sizes for emphasis marks in these code points. The UA may opt to use a font known to be good for emphasis marks, or the marks may instead be synthesized by the UA. Marks must remain upright in both horizontal and vertical typographic modes: they do not rotate to match the writing mode.

The marks are drawn once for each grapheme cluster. However, emphasis marks are not drawn for a grapheme cluster consisting of:

• Word separators or characters belonging to the Unicode separator classes (Z*). (But note that emphasis marks are drawn for a space that combines with any combining characters.)
• Characters belonging to the Unicode classes for control codes and unassigned characters (Cc, Cf, Cn).
• Anything else? Probably need to exclude punctuation, but which punctuation exactly? Can we determine that Unicode-wide?

If emphasis marks are drawn for grapheme clusters for which ruby is drawn in the same position as the emphasis mark, the ruby should be stacked between the emphasis marks and the base text. In this case, the position of the emphasis marks for a given element should be determined as if all grapheme clusters have ruby boxes of the same height as the highest ruby box in the element. If the UA is not capable of drawing ruby and emphasis marks on the same side, the UA may hide ruby and draw only emphasis marks.

Emphasis Mark Color: the 'text-emphasis-color' property

This property describes the foreground color of the emphasis marks.

Emphasis Mark Shorthand: the 'text-emphasis' property

This property is a shorthand for setting text-emphasis-style and text-emphasis-color in one declaration. Omitted values are set to their initial values.

Note that 'text-emphasis-position' is not reset in this shorthand. This is because typically the shape and color vary, but the position is consistent for a particular language throughout the document. Therefore the position should inherit independently.

Emphasis Mark Position: the 'text-emphasis-position' property

This property describes where emphasis marks are drawn at. The values have following meanings:

''above''

Draw marks over the text in horizontal typographic mode.

''below''

Draw marks under the text in horizontal typographic mode.

''right''

Draw marks to the right of the text in vertical typographic mode.

''left''

Draw marks to the left of the text in vertical typographic mode.

Emphasis marks are drawn exactly as if each grapheme cluster was assigned the mark as its ruby annotation text with the ruby position given by 'text-emphasis-position' and the ruby alignment as centered.

The effect of emphasis marks on the line height is the same as for ruby text.

Note, the preferred position of emphasis marks depends on the language. In Japanese for example, the preferred position is ''above right''. In Chinese, on the other hand, the preferred position is ''below right''. The informative table below summarizes the preferred emphasis mark positions for Chinese and Japanese:

Preferred emphasis mark and ruby position

Language	Preferred mark position		Illustration
	Horizontal	Vertical
Japanese	above	right
Chinese	below	right

Text Shadows: the 'text-shadow' property

This property accepts a comma-separated list of shadow effects to be applied to the text of the element. <shadow> is the same as defined for the 'box-shadow' property except that the ''inset'' keyword is not allowed. The shadow is applied to all of the element's text as well as any text decorations it specifies. When a text outline is specified, the shadow shadows the outlined shape rather than the glyph shape.

The shadow effects are applied front-to-back: the first shadow is on top. The shadows may thus overlay each other, but they never overlay the text itself. The shadow must be painted at a stack level between the element's border and/or background, if present, and the elements text and text decoration. UAs should avoid painting text shadows over text in adjacent elements belonging to the same stack level and stacking context. (This may mean that the exact stack level of the shadows depends on whether the element has a border or background: the exact stacking behavior of text shadows is thus UA-defined.)

Unlike 'box-shadow', text shadows are not clipped to the shadowed shape and may show through if the text is partially-transparent. Like 'box-shadow', text shadows do not influence layout, and do not trigger scrolling or increase the size of the scrollable area.

The painting order of shadows defined here is the opposite of that defined in the 1998 CSS2 Recommendation.

The text-shadow property applies to both the ::first-line and ::first-letter pseudo-elements.

Text Outlines: the 'text-outline' property

This property specifies a text outline where the first length represents the outline's thickness and the second represents an optional blur radius. The outline never overlays the text itself. Its shape is the same as that obtained by applying text shadows in every radial direction, i.e. all text shadows whose offsets satisfy the equation x2 + y2 = thickness2. The blur radius is treated the same as for 'text-shadow'.

The Timed-Text WG had suggestions for some keywords (text-outline: normal|heavy|light;) as well as a <length> thickness. Should these be added? How would they be defined? (Maybe use (thin|medium|thick) as in border-width?)

A color value must be specified before or after the length values of the outline effect. The color value will be used as the color of the outline.

Implementations may ignore the blur radius when text outline is combined with a text shadow.

The spread radius argument added to the 'text-shadow' property makes this property somewhat redundant. Should it be kept?

Changes

Changes from the October 2010 CSS3 Text WD

Major changes include:

• Updated line break transformation rules to use East Asian Width property, consistent with behavior in MSIE.
• Moved ''keep-all'' value of 'line-break' back to 'word-break' and adjusted explanation of properties to match this split.
• Added ''keep-words'' value to 'word-break'.
• Renamed ''newspaper'' value of 'line-break' to ''loose''.
• Copied hyphenation controls over from CSS3 Generated Content for Paged Media Module and updated with feedback from TPAC and Oslo F2F.
• Renamed ''suppress'' value of 'text-wrap' to ''avoid'' to be consistent with 'page-break-inside', which has similar behavior.
• Added more details to behavior of 'text-align' with <string> values.
• Added 'text-align-first'.
• Added ''auto'' value to 'text-align-last'.
• Added ''none'' value ot 'text-justify'.
• Reorganized values of 'punctuation-trim' and renamed to 'text-trim'.
• Removed ''trim'' keyword of 'text-justify' to control it through 'text-trim'.
• Removed ''ideograph-space'' and ''ideograph-parenthesis'' values of 'text-autospace'.
• Changed definitions of ideographic letters, non-ideographic letters, and non-ideographic numerals for 'text-autospace'.
• Changed values of 'text-emphasis-position' and 'text-underline-position' to allow specifying common combinations of horizontal and vertical positions.
• Changed preferred value of 'text-emphasis-position' for Chinese (Traditional).
• Removed definition of the 'text-overflow' property, which has been moved to [[CSS3UI]].

Acknowledgements

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

Appendix A: References

Normative references

Informative references

Appendix B: Property index

Appendix C: Default UA Stylesheet

This section is informative, and is to help UA developers to implement default stylesheet, but UA developers are free to ignore or change.

/* make list items align together */
li { text-align: match-parent; }
/* disable inheritance of text-emphasis marks to ruby text:
  emphasis marks should only apply to base text */
rt { text-emphasis: none; }

:root:lang(zh) {
/* default emphasis mark position is 'under' for Chinese */
  text-emphasis-position: under;
}

If you find any issues, recommendations to add, or corrections, please send the information to www-style@w3.org with [css3-text] in the subject line.

Index