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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang=en>
<head profile="http://dublincore.org/documents/2008/08/04/dc-html/ ">
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Text Decoration Module Level 3</title>
<link href="http://purl.org/dc/terms/" rel=schema.dcterms>
<link href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=dcterms.rights>
<meta content="CSS Text Decoration Module Level 3" name=dcterms.title>
<meta content=text name=dcterms.type>
<meta content=2013-06-10 name=dcterms.date>
<meta content="Elika J. Etemad" name=dcterms.creator>
<meta content="Koji Ishii" name=dcterms.creator>
<meta content=W3C name=dcterms.publisher>
<meta content="http://dev.w3.org/csswg/css-text-decor-3/"
name=dcterms.identifier>
<link href="#contents" rel=contents><!--<link rel=index href="#index">-->
<link href="../default.css" rel=stylesheet type="text/css">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
type="text/css">
<body class=h-entry>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 class=p-name>CSS Text Decoration Module Level 3</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft <span
class=dt-updated><span class=value-title title=20130610>10 June
2013</span></span></h2>
<dl>
<dt>This version:</dt>
<!--
<dd><a class="u-url" href="http://www.w3.org/TR/2013/WD-css-text-decor-3-20130610/">http://www.w3.org/TR/2013/WD-css-text-decor-3-20130610/</a></dd>
-->
<dd><a class=u-url
href="http://dev.w3.org/csswg/css-text-decor-3/">http://dev.w3.org/csswg/css-text-decor-3/</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css-text-decor-3/">http://www.w3.org/TR/css-text-decor-3/</a>
<dt>Latest editor's draft:
<dd><a
href="http://dev.w3.org/csswg/css-text-decor-3/">http://dev.w3.org/csswg/css-text-decor-3/</a>
<dt>Previous version:
<dd><a href="http://www.w3.org/TR/2012/WD-css-text-decor-3-20121113/"
rel=previous>http://www.w3.org/TR/2012/WD-css-text-decor-3-20121113/</a>
<dt>Issues List:
<dd><a href="http://www.w3.org/Style/CSS/Tracker/products/10"
rel=issues>http://www.w3.org/Style/CSS/Tracker/products/10</a>
<dt>Feedback:
<dd><a
href="mailto:www-style@w3.org?subject=%5Bcss-text-decor%5D%20feedback">www-style@w3.org</a>
with subject line “<kbd>[css-text-decor] <var>… message topic
…</var></kbd>” (<a
href="http://lists.w3.org/Archives/Public/www-style/"
rel=discussion>archives</a>)
<dt>Editors:
<dd class="p-author h-card vcard"> <a class="p-name fn u-url url"
href="http://fantasai.inkedblade.net/contact" rel=author>Elika J.
Etemad</a> (<span class="p-org org">Mozilla</span>)
<dd class="p-author h-card vcard"> <a class="p-name fn u-email email"
href="mailto:koji.a.ishii@mail.rakuten.com" rel=author>Koji Ishii</a>
(<span class="p-org org">Rakuten, Inc.</span>)
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><abbr
title="Massachusetts Institute of Technology">MIT</abbr></a>, <a
href="http://www.ercim.eu/"><abbr
title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
<a href="http://www.keio.ac.jp/">Keio</a>, <a
href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p> <span class=p-summary> This module contains the features of CSS
relating to text decoration, such as underlines, text shadows, and
emphasis marks. </span> <a href="http://www.w3.org/TR/CSS/">CSS</a> is a
language for describing the rendering of structured documents (such as
HTML and XML) on screen, on paper, in speech, etc.
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<p><em>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 <a href="http://www.w3.org/TR/">W3C technical reports
index at http://www.w3.org/TR/.</a></em>
<p>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.
<p>This CSS module has been produced as a combined effort of the <a
href="http://www.w3.org/International/Activity">W3C Internationalization
Activity</a>, and the <a href="http://www.w3.org/Style/Activity">Style
Activity</a> and is maintained by the <a
href="http://www.w3.org/Style/CSS/members">CSS Working Group</a>. It also
includes contributions made by participants in the <a
href="http://www.w3.org/Style/XSL/Group/">XSL Working Group</a> (<a
href="http://cgi.w3.org/MemberAccess/AccessRequest">members only</a>).
<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a
href="http://www.w3.org/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> 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 <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.
<p><strong>Feedback on this draft should be posted to the (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org">www-style@w3.org</a></strong> (see <a
href="http://www.w3.org/Mail/Request">instructions</a>) <strong>with
<kbd>[text-decor-3]</kbd> in the subject line.</strong> 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.
<p>The following features are at risk and may be cut from the spec during
its CR period if there are no (correct) implementations:
<ul>
<li>the ‘<a href="#text-decoration-skip"><code
class=property>text-decoration-skip</code></a>’ property
<li>the <a href="#line-position">line positioning rules</a>
<li>the ability to place both emphasis marks and ruby above the same base
text
</ul>
<h2 class="no-num no-toc" id=contents> Table of Contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#intro"><span class=secno>1. </span> Introduction</a>
<ul class=toc>
<li><a href="#placement"><span class=secno>1.1. </span> Module
Interactions</a>
<li><a href="#values"><span class=secno>1.2. </span> Values</a>
<li><a href="#terms"><span class=secno>1.3. </span>Terminology</a>
</ul>
<li><a href="#line-decoration"><span class=secno>2. </span> Line
Decoration: Underline, Overline, and Strike-Through</a>
<ul class=toc>
<li><a href="#text-decoration-line-property"><span class=secno>2.1.
</span> Text Decoration Lines: the ‘<code
class=property>text-decoration-line</code>’ property</a>
<li><a href="#text-decoration-color-property"><span class=secno>2.2.
</span> Text Decoration Color: the ‘<code
class=property>text-decoration-color</code>’ property</a>
<li><a href="#text-decoration-style-property"><span class=secno>2.3.
</span> Text Decoration Style: the ‘<code
class=property>text-decoration-style</code>’ property</a>
<li><a href="#text-decoration-property"><span class=secno>2.4. </span>
Text Decoration Shorthand: the ‘<code
class=property>text-decoration</code>’ property</a>
<li><a href="#text-decoration-skip-property"><span class=secno>2.5.
</span> Text Decoration Line Continuity: the ‘<code
class=property>text-decoration-skip</code>’ property</a>
<li><a href="#text-underline-position-property"><span class=secno>2.6.
</span> Text Underline Position: the ‘<code
class=property>text-underline-position</code>’ property</a>
</ul>
<li><a href="#emphasis-marks"><span class=secno>3. </span> Emphasis
Marks</a>
<ul class=toc>
<li><a href="#text-emphasis-style-property"><span class=secno>3.1.
</span> Emphasis Mark Style: the ‘<code
class=property>text-emphasis-style</code>’ property</a>
<li><a href="#text-emphasis-color-property"><span class=secno>3.2.
</span> Emphasis Mark Color: the ‘<code
class=property>text-emphasis-color</code>’ property</a>
<li><a href="#text-emphasis-property"><span class=secno>3.3. </span>
Emphasis Mark Shorthand: the ‘<code
class=property>text-emphasis</code>’ property</a>
<li><a href="#text-emphasis-position-property"><span class=secno>3.4.
</span> Emphasis Mark Position: the ‘<code
class=property>text-emphasis-position</code>’ property</a>
</ul>
<li><a href="#text-shadow-property"><span class=secno>4. </span> Text
Shadows: the ‘<code class=property>text-shadow</code>’ property</a>
<li><a href="#painting-order"><span class=secno>5. </span> Painting Order
of Text Decorations</a>
<li><a href="#conformance"><span class=secno>6. </span> Conformance</a>
<ul class=toc>
<li><a href="#conventions"><span class=secno>6.1. </span> Document
Conventions</a>
<li><a href="#conformance-classes"><span class=secno>6.2. </span>
Conformance Classes</a>
<li><a href="#partial"><span class=secno>6.3. </span> Partial
Implementations</a>
<li><a href="#experimental"><span class=secno>6.4. </span> Experimental
Implementations</a>
<li><a href="#testing"><span class=secno>6.5. </span>Non-Experimental
Implementations</a>
<li><a href="#cr-exit-criteria"><span class=secno>6.6. </span> CR Exit
Criteria</a>
</ul>
<li class=no-num><a href="#acknowledgements"> Appendix A:
Acknowledgements</a>
<li class=no-num><a href="#appendix-b-references">Appendix B:
References</a>
<ul class=toc>
<li class=no-num><a href="#normative-ref">Normative references</a>
<li class=no-num><a href="#informative-ref">Informative references</a>
</ul>
<li class=no-num><a href="#changes">Appendix C: Changes</a>
<ul class=toc>
<li class=no-num><a href="#recent-changes"> Changes since the January
2013 Last Call Working Draft</a>
</ul>
<li class=no-num><a href="#default-stylesheet"> Appendix D: Default UA
Stylesheet</a>
</ul>
<!--end-toc-->
<h2 id=intro><span class=secno>1. </span> Introduction</h2>
<p><em>This subsection is non-normative.</em>
<p>This module covers text decoration, i.e. decorating the glyphs of the
text once typeset according to font and typographic rules. (See <a
href="#CSS3TEXT" rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> and <a
href="#CSS3-FONTS" rel=biblioentry>[CSS3-FONTS]<!--{{CSS3-FONTS}}--></a>.)
Such features are traditionally used not only for purely decorative
purposes, but also in some cases to show emphasis, for honorifics, and to
indicate editorial changes such as insertions, deletions, and
misspellings.
<p>CSS Levels 1 and 2 only defined very basic <a
href="#line-decoration">line decorations</a> (underlines, overlines, and
strike-throughs) appropriate to Western typographical traditions. Level 3
of this module adds the ability to change the color, style, position, and
continuity of these decorations, and also introduces <a
href="#emphasis-marks">emphasis marks</a> (traditionally used in East
Asian typography), and <a href="#text-shadow-property">shadows</a> (which
were proposed then deferred from Level 2).
<h3 id=placement><span class=secno>1.1. </span> Module Interactions</h3>
<p>This module replaces and extends the text-decorating features defined in
<a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> chapter 16.
<h3 id=values><span class=secno>1.2. </span> Values</h3>
<p>This specification follows the <a
href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
definition conventions</a> from <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. Value types not defined in
this specification are defined in CSS Level 2 Revision 1 <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. Other CSS
modules may expand the definitions of these value types: for example <a
href="#CSS3COLOR" rel=biblioentry>[CSS3COLOR]<!--{{CSS3COLOR}}--></a>,
when combined with this module, expands the definition of the
<color> value type as used in this specification.
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification also accept the <a
href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
keyword as their property value. For readability it has not been repeated
explicitly.
<h3 id=terms><span class=secno>1.3. </span>Terminology</h3>
<p>The terms <a
href="http://www.w3.org/TR/css3-text/#grapheme-cluster"><dfn
id=character>character</dfn></a>, <a
href="http://www.w3.org/TR/css3-text/#letter"><dfn
id=letter>letter</dfn></a>, and <a
href="http://www.w3.org/TR/css3-text/#content-language"><dfn
id=content-language>content language</dfn></a> as used in this
specification are defined in <a href="#CSS3TEXT"
rel=biblioentry>[CSS3TEXT]<!--{{!CSS3TEXT}}--></a>. Other terminology and
concepts used in this specification are defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> and <a
href="#CSS3-WRITING-MODES"
rel=biblioentry>[CSS3-WRITING-MODES]<!--{{!CSS3-WRITING-MODES}}--></a>.
<h2 id=line-decoration><span class=secno>2. </span> Line Decoration:
Underline, Overline, and Strike-Through</h2>
<p> The following properties describe line decorations that are added to
the content of an element. When specified on or propagated to an inline
box, that box becomes a <dfn id=decorating-box>decorating box</dfn> for
that decoration, applying the decoration to all its fragments. The
decoration is then further propagated to any in-flow block-level boxes
that split the inline (see <a
href="http://www.w3.org/TR/CSS21/visuren.html#anonymous-block-level">CSS2.1
section 9.2.1.1</a>). When specified on or propagated to a block container
that establishes an inline formatting context, the decorations are
propagated to an anonymous inline box that wraps all the in-flow
inline-level children of the block container. When specified on or
propagated to a ruby box, the decorations are propagated only to the ruby
base. For all other box types, the decorations are propagated to all
in-flow children.
<p class=note> Note that text decorations are not propagated to any
out-of-flow descendants, nor to the contents of atomic inline-level
descendants such as inline blocks and inline tables. They are also not
propagated to inline children of inline boxes, although the decoration is
<em>applied</em> to such boxes.
<p> By default underlines, overlines, and line-throughs are applied only to
non-replaced inline boxes, and are drawn across all text (including white
space, letter spacing, and word spacing). Atomic inlines, such as images,
are not decorated. The ‘<a href="#text-decoration-skip"><code
class=property>text-decoration-skip</code></a>’ property can be used to
modify this behavior, for example allowing atomic inlines to be underlined
or requiring that white space be skipped. Margins, borders, and padding of
the <a href="#decorating-box"><i>decorating box</i></a> are always
skipped.
<p>Relatively positioning a descendant moves all text decorations applied
to it along with the descendant's text; it does not affect calculation of
the decoration's initial position on that line. The ‘<code
class=property>visibility</code>’ property, ‘<a
href="#text-shadow"><code class=property>text-shadow</code></a>’,
filters, and other graphical transformations likewise affect text
decorations as part of the text they're drawn on, even if the decorations
were specified on an ancestor box, and do not affect the calculation of
their initial positions or thicknesses. (In the case of line decorations
drawn over an atomic inline or across box decorations, they are
analogously associated with the affected box rather than the <a
href="#decorating-box"><i>decorating box</i></a>.)
<div class=example>
<p>In the following style sheet and document fragment:
<pre>
<!-- --> blockquote { text-decoration: underline; color: blue; }
<!-- --> em { display: block; }
<!-- --> cite { color: fuchsia; }</pre>
<pre>
<!-- --> <blockquote>
<!-- --> <p>
<!-- --> <span>
<!-- --> Help, help!
<!-- --> <em> I am under a hat! </em>
<!-- -->
<!-- --> <cite> —GwieF </cite>
<!-- --> </span>
<!-- --> </p>
<!-- --> </blockquote></pre>
<p>...the underlining for the blockquote element is propagated to an
anonymous inline box that surrounds the span element, causing the text
"Help, help!" to be blue, with the blue underlining from the anonymous
inline underneath it, the color being taken from the blockquote element.
The <code><em>text</em></code> in the em block is also
underlined, as it is in an in-flow block to which the underline is
propagated. The final line of text is fuchsia, but the underline
underneath it is still the blue underline from the anonymous inline
element.
<p><img alt="Sample rendering of the above underline example"
src=underline-example.png>
<p>This diagram shows the boxes involved in the example above. The rounded
aqua line represents the anonymous inline element wrapping the inline
contents of the paragraph element, the rounded blue line represents the
span element, and the orange lines represent the blocks.
</div>
<h3 id=text-decoration-line-property><span class=secno>2.1. </span> Text
Decoration Lines: the ‘<a href="#text-decoration-line"><code
class=property>text-decoration-line</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-decoration-line>text-decoration-line</dfn>
<tr>
<th><a href="#values">Value</a>:
<td>none | [ underline || overline || line-through || blink ]
<tr>
<th>Initial:
<td>none
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no (but see prose)
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
<tr>
<th>Animatable:
<td>no
</table>
<p>Specifies what line decorations, if any, are added to the element.
Values have the following meanings:
<dl>
<dt><dfn id=none title="text-decoration-line:none">‘<code
class=css>none</code>’</dfn>
<dd>Neither produces nor inhibits text decoration.
<dt><dfn id=underline>‘<code class=css>underline</code>’</dfn>
<dd>Each line of text is underlined.
<dt><dfn id=overline>‘<code class=css>overline</code>’</dfn>
<dd>Each line of text has a line over it (i.e. on the opposite side from
an underline).
<dt><dfn id=line-through>‘<code class=css>line-through</code>’</dfn>
<dd>Each line of text has a line through the middle.
<dt><dfn id=blink>‘<code class=css>blink</code>’</dfn>
<dd> 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 <a
href="http://www.w3.org/TR/UAAG/guidelines.html#tech-on-off-blinking-text">checkpoint
3.3 of WAI-UAAG</a>. This value is <strong>deprecated</strong> in favor
of Animations <a href="#CSS3-ANIMATIONS"
rel=biblioentry>[CSS3-ANIMATIONS]<!--{{CSS3-ANIMATIONS}}--></a>.
</dl>
<h3 id=text-decoration-color-property><span class=secno>2.2. </span> Text
Decoration Color: the ‘<a href="#text-decoration-color"><code
class=property>text-decoration-color</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-decoration-color>text-decoration-color</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a href="http://www.w3.org/TR/css3-color/#color0"><span
class=value-inst-color><color></span></a>
<tr>
<th>Initial:
<td><a
href="http://www.w3.org/TR/css3-color/#currentcolor">currentColor</a>
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>the computed color
<tr>
<th>Animatable:
<td>as <a
href="http://www.w3.org/TR/css3-transitions/#animtype-color">color</a>
</table>
<p>This property specifies the color of text decoration (underlines
overlines, and line-throughs) set on the element with ‘<a
href="#text-decoration-line"><code
class=property>text-decoration-line</code></a>’.
<p> The color of text decorations must remain the same on all decorations
originating from a given element, even if descendant boxes have different
specified colors.
<h3 id=text-decoration-style-property><span class=secno>2.3. </span> Text
Decoration Style: the ‘<a href="#text-decoration-style"><code
class=property>text-decoration-style</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-decoration-style>text-decoration-style</dfn>
<tr>
<th><a href="#values">Value</a>:
<td>solid | double | dotted | dashed | wavy
<tr>
<th>Initial:
<td>solid
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
<tr>
<th>Animatable:
<td>no
</table>
<p>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 <a
href="http://www.w3.org/TR/css3-background/#the-border-style">border-style
properties</a> <a href="#CSS3BG"
rel=biblioentry>[CSS3BG]<!--{{!CSS3BG}}--></a>. ‘<code
class=css>wavy</code>’ indicates a wavy line.
<p> The style of text decorations must remain the same on all decorations
originating from a given element, even if descendant boxes have different
specified styles.
<h3 id=text-decoration-property><span class=secno>2.4. </span> Text
Decoration Shorthand: the ‘<a href="#text-decoration"><code
class=property>text-decoration</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-decoration>text-decoration</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><var><a
href="#text-decoration-line"><text-decoration-line></a></var> ||
<var><a
href="#text-decoration-style"><text-decoration-style></a></var>
|| <var><a
href="#text-decoration-color"><text-decoration-color></a></var>
<tr>
<th>Initial:
<td>none
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>see individual properties
<tr>
<th>Animatable:
<td>see individual properties
</table>
<p>This property is a shorthand for setting ‘<a
href="#text-decoration-line"><code
class=property>text-decoration-line</code></a>’, ‘<a
href="#text-decoration-color"><code
class=property>text-decoration-color</code></a>’, and ‘<a
href="#text-decoration-style"><code
class=property>text-decoration-style</code></a>’ in one declaration.
Omitted values are set to their initial values. A ‘<a
href="#text-decoration"><code class=property>text-decoration</code></a>’
declaration that omits both the ‘<a href="#text-decoration-color"><code
class=property>text-decoration-color</code></a>’ and ‘<a
href="#text-decoration-style"><code
class=property>text-decoration-style</code></a>’ values is
backwards-compatible with CSS Levels 1 and 2.
<div class=example>
<p>The following example underlines unvisited links with a solid blue
underline in CSS1 and CSS2 UAs and a navy dotted underline in CSS3 UAs.
<pre><code class=css>
<!-- -->:link {
<!-- --> color: blue;
<!-- --> text-decoration: underline;
<!-- --> text-decoration: navy dotted underline; /* <a
href="http://www.w3.org/TR/CSS21/syndata.html#ignore">Ignored</a> in CSS1/CSS2 UAs */
<!-- -->}</code></pre>
</div>
<h3 id=text-decoration-skip-property><span class=secno>2.5. </span> Text
Decoration Line Continuity: the ‘<a href="#text-decoration-skip"><code
class=property>text-decoration-skip</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-decoration-skip>text-decoration-skip</dfn>
<tr>
<th><a href="#values">Value</a>:
<td>none | [ objects || spaces || ink || edges || box-decoration ]
<tr>
<th>Initial:
<td>objects
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>yes
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
<tr>
<th>Animatable:
<td>no
</table>
<p>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:
<dl>
<dt><dfn id=none0 title="text-decoration-skip:none">‘<code
class=css>none</code>’</dfn>
<dd>Skip nothing: text-decoration is drawn for all text content and across
atomic inline-level boxes.
<dt><dfn id=objects title="text-decoration-skip:objects">‘<code
class=css>objects</code>’</dfn>
<dd>Skip this element (its entire margin box) if it is an atomic inline
(such as an image or inline-block).
<dt><dfn id=spaces title="text-decoration-skip:spaces">‘<code
class=css>spaces</code>’</dfn>
<dd>Skip all spacing, i.e. all <a href="#character"><i>characters</i></a>
with the Unicode White_Space property <a href="#UAX44"
rel=biblioentry>[UAX44]<!--{{UAX44}}--></a> and all <i>word separator
characters</i>, plus any adjacent letter-spacing or word-spacing <a
href="#CSS3TEXT" rel=biblioentry>[CSS3TEXT]<!--{{!CSS3TEXT}}--></a>.
<dt><dfn id=ink title="text-decoration-skip:ink">‘<code
class=css>ink</code>’</dfn>
<dd>Skip over where glyphs are drawn: interrupt the decoration line to let
the shape of the text show through where the text decoration would
otherwise cross over a glyph. The UA must skip a small distance to either
side of the glyph outline.
<div class=figure>
<p><img
alt="An alphabetic underline through Myanmar text skips around descenders and the vertical strokes of combining characters that drop below the alphabetic baseline."
src=decoration-skip-ink.png title="text-decoration-skip: ink">
<p class=caption>‘<code class=css>text-decoration-skip: ink</code>’
</div>
<dt><dfn id=edges title="text-decoration-skip:edges">‘<code
class=css>edges</code>’</dfn>
<dd>The UA should place the start and end of the line inwards slightly
(e.g. by half a line thickness) from the content edge of the <a
href="#decorating-box"><i>decorating box</i></a> 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.)
<div class=figure>
<p><img
alt="An underline below a series of Chinese characters has a gap between two adjacent underlining elements."
src=decoration-skip-edges.png title="text-decoration-skip: edges">
<p class=caption>‘<code class=css>text-decoration-skip:
edges</code>’ for
<code><u>石井</u><u>艾俐俐</u></code>
</div>
<dt><dfn id=box-decoration
title="text-decoration-skip:box-decoration">‘<code
class=css>box-decoration</code>’</dfn>
<dd> Skip over the box's margin, border, and padding areas. Note that this
only has an effect on decorations imposed by an ancestor; a <a
href="#decorating-box"><i>decorating box</i></a> never draws over its own
box decoration.
</dl>
<p class=note>Note that this property inherits and that descendant elements
can have a different setting.
<p class=note> Note that CSS 2.1 required skipping margins, borders, and
padding always. In this level, by default only the margins, borders, and
padding of the <a href="#decorating-box"><i>decorating box</i></a> are
skipped. In the future CSS2.1 may be updated to match this new default.
<h3 id=text-underline-position-property><span class=secno>2.6. </span> Text
Underline Position: the ‘<a href="#text-underline-position"><code
class=property>text-underline-position</code></a>’ property</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td><dfn id=text-underline-position>text-underline-position</dfn>
<tr>
<th><a href="#values">Value</a>:
<td>auto | alphabetic | [ under || [ left | right ] ]
<tr>
<th>Initial:
<td>auto
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>yes
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
<tr>
<th>Animatable:
<td>no
</table>
<p>This property sets the position of an underline specified on the
element. (It does not affect underlines specified by ancestor elements.)
If ‘<code class=css>left</code>’ or ‘<code class=css>right</code>’
is specified alone, ‘<code class=css>under</code>’ is also implied.
<div class=example>
<p>The following example styles modern Chinese, Japanese, and Korean texts
with the appropriate underline positions in both horizontal and vertical
text:
<pre>:root:lang(ja), [lang|=ja], :root:lang(ko), [lang|=ko] { text-underline-position: under right; }
<!-- -->:root:lang(zh), [lang|=zh] { text-underline-position: under left; }</pre>
<p>(Note that these rules are part of the suggested <a
href="#default-stylesheet">default UA style sheet</a>.)
</div>
<p>Values have the following meanings:
<dl>
<dt><dfn id=underline-auto title="text-underline-position: auto">‘<code
class=css>auto</code>’</dfn>
<dd>The user agent may use any algorithm to determine the underline's
position; however it must be placed at or under the alphabetic baseline.
<p class=note>It is suggested that the underline position be ‘<code
class=css>alphabetic</code>’ 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 ‘<code
class=css>under</code>’ is more appropriate.
<p class=issue>See also
http://lists.w3.org/Archives/Public/www-style/2010Dec/0409.html
<dt><dfn id=underline-alphabetic
title="text-underline-position: alphabetic">‘<code
class=css>alphabetic</code>’</dfn>
<dd>The underline is positioned relative to the alphabetic baseline. In
this case the underline is likely to cross some descenders.
<div class=figure>
<p><img
alt="In a typical Latin font, the underline is positioned slightly below the alphabetic baseline, leaving a gap between the line and the bottom of most Latin letters, but crossing through descenders such as the stem of a 'p'."
src=underline-position-alphabetic.png
title="text-underline-position: alphabetic">
<p class=caption>‘<a href="#underline-alphabetic"><code
class=css>text-underline-position: alphabetic</code></a>’
</div>
<dt><dfn id=underline-under
title="text-underline-position: under">‘<code
class=css>under</code>’</dfn>
<dd>The underline is positioned <i>under</i> the element's text content.
In this case the underline usually does not cross the descenders. (This
is sometimes called "accounting" underline.) This value can be combined
with ‘<code class=css>left</code>’ or ‘<code
class=css>right</code>’ if a particular side is preferred in vertical
writing modes.
<div class=figure>
<p><img
alt="In a typical Latin font, the underline is far enough below the text that it does not cross the bottom of a 'g'."
src=underline-position-under.png
title="text-underline-position: under">
<p class=caption>‘<a href="#underline-under"><code
class=css>text-underline-position: under</code></a>’
</div>
<div class=example>
<p>Because ‘<a href="#text-underline-position"><code
class=property>text-underline-position</code></a>’ inherits, and is
not reset by the ‘<a href="#text-decoration"><code
class=property>text-decoration</code></a>’ shorthand, the following
example switches the document to use ‘<code class=css>under</code>’
underlining, which can be more appropriate for writing systems with
long, complicated descenders. It is also often useful for mathematical
or chemical texts that use many subscripts.
<pre>:root { text-underline-position: under; }</pre>
</div>
<dt><dfn id=underline-left title="text-underline-position: left">‘<code
class=css>left</code>’</dfn>
<dd>In vertical writing modes, the underline is aligned as for ‘<code
class=css>under</code>’, except it is always aligned to the left 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