csswg-drafts/css-style-attr/Overview.html at f5d23dbfbfeaf3ced88c321d06c9aed561c70e1c · w3c/csswg-drafts · GitHub

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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 Style Attributes</title>

  <link href="http://purl.org/dc/terms/" rel=schema.dcterms>
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  <meta content="CSS Style Attributes" name=dcterms.title>
  <meta content=text name=dcterms.type>
  <meta content=2015-04-10 name=dcterms.date>
  <meta content="Tantek Çelik" name=dcterms.creator>
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  <script defer=defer
   src="https://test.csswg.org/harness/annotate.js#css-style-attr-1_dev"
   type="text/javascript"></script>

 <body class=h-entry>
  <div class=head> <!--begin-logo-->
   <p><a href="http://www.w3.org/"><img alt=W3C height=48
    src="https://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->

   <h1 class=p-name>CSS Style Attributes</h1>

   <h2 class="no-num no-toc">Editor's Draft <span class=dt-updated><span
    class=value-title title=20150410>10 April 2015</span></span></h2>

   <dl>
    <dt>This version:

    <dd><a class=u-url
     href="http://dev.w3.org/csswg/css-style-attr/">http://dev.w3.org/csswg/css-style-attr/</a>

    <dt>Latest version:

    <dd><a
     href="http://www.w3.org/TR/css-style-attr/">http://www.w3.org/TR/css-style-attr/</a>

    <dt>Editor's draft:

    <dd><a
     href="http://dev.w3.org/csswg/css-style-attr/">http://dev.w3.org/csswg/css-style-attr/</a>
     (<a
     href="https://hg.csswg.org/drafts/log/tip/css-style-attr/Overview.src.html">change
     log</a>)

    <dt>Previous version:

    <dd><a
     href="http://www.w3.org/TR/2013/PR-css-style-attr-20131003/">http://www.w3.org/TR/2013/PR-css-style-attr-20131003/</a>

    <dt>Feedback:

    <dd><a
     href="mailto:www-style@w3.org?subject=%5Bcss-style-attr%5D%20feedback">www-style@w3.org</a>
     with subject line “<kbd>[css-style-attr] <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://tantek.com/" lang=tr rel=author>Tantek Çelik</a> (<a
     class="p-org org h-org" href="https://mozilla.org/">Mozilla</a>, and
     formerly at <a href="http://microsoft.com/">Microsoft Corporation</a>)
     &lt;<a class="u-email email"
     href="mailto:tantek@cs.stanford.edu">tantek@cs.stanford.edu</a>&gt;

    <dd class="p-author h-card vcard"> <a class="p-name fn n u-url u
8000
rl"
     href="http://fantasai.inkedblade.net/contact" rel=author><span
     class="p-given-name given-name">Elika</span> <abbr
     class="p-additional-name additional-name">J.</abbr> <span
     class="p-family-name family-name">Etemad</span></a> (<a
     class="p-org org h-org" href="https://mozilla.org/">Mozilla</a>)

    <dt>Previous Editors:

    <dd class=vcard><a class="fn url"
     href="http://www.w3.org/People/Bos/">Bert Bos</a> (<a class=org
     href="http://www.w3.org/">W3C</a>), &lt;<a class=email
     href="mailto:bert@w3.org">bert@w3.org</a>&gt;

    <dd class=vcard><span class=fn>Marc Attinasi</span> (<span
     class=org>AOL/Netscape</span>), &lt;<a class=email
     href="mailto:attinasi@netscape.com">attinasi@netscape.com</a>&gt;

    <dt>Test suite:

    <dd> <a
     href="http://test.csswg.org/suites/css-style-attr/nightly-unstable/">http://test.csswg.org/suites/css-style-attr/nightly-unstable/</a>
   </dl>
   <!--begin-copyright-->
   <p class=copyright><a
    href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
    rel=license>Copyright</a> © 2015 <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>,
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    href="http://www.w3.org/Consortium/Legal/copyright-documents">document
    use</a> rules apply.</p>
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   <hr title="Separator for header">
  </div>

  <h2 class="no-num no-toc" id=abstract>Abstract</h2>

  <p><span class=p-summary> Markup languages such as HTML <a
   href="#ref-HTML401" rel=biblioentry>[HTML401]<!--{{HTML401}}--></a> and
   SVG <a href="#ref-SVG11" rel=biblioentry>[SVG11]<!--{{SVG11}}--></a>
   provide a style attribute on most elements, to hold inline style
   information that applies to those elements. This draft describes the
   syntax and interpretation of the CSS fragment that can be used in such
   style attributes. </span>

  <h2 class="no-num no-toc" id=status>Status of this document</h2>
  <!--begin-status-->

  <p>This is a public copy of the editors' draft. It is provided for
   discussion only and may change at any moment. Its publication here does
   not imply endorsement of its contents by W3C. Don't cite this document
   other than as work in progress.

  <p>The (<a
   href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
   mailing list <a
   href="mailto:www-style@w3.org?Subject=%5Bcss-style-attr%5D%20PUT%20SUBJECT%20HERE">
   www-style@w3.org</a> (see <a
   href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
   discussion of this specification. When sending e-mail, please put the text
   “css-style-attr” in the subject, preferably like this:
   “[<!---->css-style-attr<!---->] <em>…summary of comment…</em>”

  <p>This document was produced by the <a
   href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
   the <a href="http://www.w3.org/Style/">Style Activity</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>
  <!--end-status-->

  <p>For this specification to exit the CR stage, the following conditions
   shall be met:

  <ol>
   <li>
    <p>There must be at least two interoperable implementations. For the
     purposes of this criterion, we define the following terms:

    <dl>
     <dt>interoperable

     <dd>
      <p>passing the respective test case(s) in the <a
       href="http://www.w3.org/Style/CSS/Test/">CSS test suite</a>, or, if
       the implementation is not a Web browser, an equivalent test. Every
       relevant test in the test suite should have an equivalent test created
       if such a user agent (UA) is to be used to claim interoperability. In
       addition if such a UA is to be used to claim interoperability, then
       there must one or more additional UAs which can also pass those
       equivalent tests in the same way for the purpose of interoperability.
       The equivalent tests must be made publicly available for the purposes
       of peer review.

     <dt>implementation

     <dd>
      <p>a user agent which:

      <ol>
       <li>implements the specification.

       <li>is available (i.e. publicly downloadable or available through some
        other public point of sale mechanism). This is the "show me"
        requirement.

       <li>is shipped, or is a "nightly build" (i.e., a development version
        for the next release), but is not experimental (i.e., a version
        specifically designed to pass the test suite and not intended for
        daily usage going forward).
      </ol>
    </dl>

   <li>
    <p>A minimum of three months of the CR period must elapse. That is, this
     specification will not exit CR before (DATE OF PUBLICATION PLUS THREE
     MONTHS). When the specification exits CR, an implementation report will
     be published. At this point, no such report exists.
  </ol>

  <p>A CSS Style Attributes <a href="http://www.w3.org/Style/CSS/Test/">Test
   Suite</a> will be developed during the Candidate Recommendation phase of
   this CSS Style Attributes specification.

  <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>

   <li><a href="#conformance"><span class=secno>2. </span>Conformance</a>

   <li><a href="#syntax"><span class=secno>3. </span>Syntax and Parsing</a>

   <li><a href="#interpret"><span class=secno>4. </span>Cascading and
    Interpretation</a>

   <li><a href="#changes"><span class=secno>5. </span>Changes</a>

   <li><a href="#ack"><span class=secno>6. </span>Acknowledgments</a>

   <li><a href="#references"><span class=secno>7. </span>References </a>
    <ul class=toc>
     <li class=no-num><a href="#normative-references">Normative
      references</a>

     <li class=no-num><a href="#informative-references">Informative
      references</a>
    </ul>
  </ul>
  <!--end-toc-->

  <h2 id=intro><span class=secno>1. </span>Introduction</h2>

  <p>Some document formats have a <dfn id=style-attribute>style
   attribute</dfn> to permit the author to directly apply style information
   to specific elements in documents. If a document format defines a style
   attribute (whether named ‘<code class=property>style</code>’ or
   something else) and the attribute accepts CSS as its value, then this
   specification defines that style attribute’s syntax and interpretation.

  <div class=example>
   <p>The following example shows the use of the <code>style</code> attribute
    in HTML <a href="#ref-HTML401"
    rel=biblioentry>[HTML401]<!--{{HTML401}}--></a>:

   <pre>&lt;p style="<em>color: #090; line-height: 1.2</em>"&gt;...&lt;/p&gt;</pre>
  </div>

  <h2 id=conformance><span class=secno>2. </span>Conformance</h2>

  <p>A document or implementation cannot conform to CSS Style Attributes
   alone, but can claim conformance to CSS Style Attributes if it satisfies
   the conformance requirements in this specification when implementing CSS
   together with style attribute handling as defined in a document language
   that has one or more CSS style attributes.

  <p>Conformance to CSS Style Attributes is defined for two classes:

  <dl>
   <dt><dfn id=document>document</dfn>

   <dd>A document represented in a document language that defines a style
    attribute for one or more of its elements.

   <dt><dfn id=interpreter>interpreter</dfn>

   <dd>Someone or something that interprets the semantics of a document and
    its associated style information. (Most CSS <a
    href="http://www.w3.org/TR/CSS21/conform.html#user-agent">user agents</a>
    fall under this category.)
  </dl>

  <p>The 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. <a
   href="#ref-RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>

  <p>Examples in this specification are introduced with the words "for
   example" or are set apart from the normative text with
   <code>class="example"</code>, like this:

  <div class=example>
   <p>This is an example of an informative example.
  </div>

  <p>Informative notes begin with the word "Note" and are set apart from the
   normative text with <code>class="note"</code>, like this:

  <p class=note>Note, this is an informative note.

  <h2 id=syntax><span class=secno>3. </span>Syntax and Parsing</h2>

  <p>The value of the style attribute must match the syntax of the contents
   of a CSS <a
   href="http://www.w3.org/TR/CSS21/syndata.html#rule-sets">declaration
   below in the terms and conventions of the <a
   href="http://www.w3.org/TR/CSS21/syndata.html#syntax">CSS core
   grammar</a>:

  <pre>
style-attribute
  : S* declaration-list
  ;

declaration-list
    : declaration [ ';' S* declaration-list ]?
    | at-rule declaration-list
    | /* empty */
    ;
</pre>

  <p class=note>Note that following the CSS2.1 convention, comment tokens are
   not shown in the rule above.

  <p>The interpreter must parse the style attribute's value using the same
   forward-compatible parsing rules that apply to parsing declaration block
   contents in a normal CSS style sheet (see <a
   href="http://www.w3.org/TR/CSS21/syndata.html">chapter 4 of the CSS2.1
   specification</a> <a href="#ref-CSS21"
   rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>), with the following
   addition: when the UA expects the start of a declaration or at-rule (i.e.,
   an IDENT token or an ATKEYWORD token) but finds an unexpected token
   instead, that token is considered to be the first token of a malformed
   declaration. I.e., the rule for malformed declarations, rather than
   malformed statements, is used to determine which tokens to ignore in that
   case.

  <p class=note>Note that because there is no open brace delimiting the
   declaration list in the CSS style attribute syntax, a close brace
   (<code>}</code>) in the style attribute's value does not terminate the
   style data: it is merely an invalid token.

  <div class=note>
   <p>Although the grammar allows it, no at-rule valid in style attributes is
    define at the moment. The forward-compatible parsing rules are such that
    a declaration following an at-rule is not ignored:

   <pre>&lt;span style="@unsupported { splines: reticulating } color: green"></pre>
  </div>

  <h2 id=interpret><span class=secno>4. </span>Cascading and Interpretation</h2>

  <p>The declarations in a style attribute apply to the element to which the
   attribute belongs. In the cascade, these declarations are considered to
   have author origin and a specificity higher than any selector. CSS2.1 <a
   href="http://www.w3.org/TR/CSS21/cascade.html#specificity">defines</a> how
   style sheets and style attributes are cascaded together. <a
   href="#ref-CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> Relative
   URLs in the style data must be resolved relative to the style attribute's
   element (or to the document if per-element resolution is not defined) when
   the attribute's value is parsed<!-- so dynamic changes to
the base URL don't affect the CSS ~Hixie -->.

  <p>Aside from the differences in cascading, the declarations in a style
   attribute must be interpreted exactly as if they were given in a CSS style
   rule that applies to the element.

  <p>The CSS Working Group strongly recommends that document languages do not
   allow multiple CSS style attributes on a single element. If a document
   language allows multiple CSS style attributes, each must be parsed
   independently and treated as a separate style rule, the ordering of which
   should be defined by the document language, else is undefined.

  <h2 id=changes><span class=secno>5. </span>Changes</h2>

  <p>Changes since the <a
   href="http://www.w3.org/TR/2013/PR-css-style-attr-20131003/">2013-10-03
   Proposed Recommendation</a> are:

  <ul>
   <li>Parse at-rules in declaration lists to allow future extension.
  </ul>

  <h2 id=ack><span class=secno>6. </span>Acknowledgments</h2>

  <p>Thanks to feedback from <span class=vcard><span class=fn>Daniel
   Glazman</span></span>, <span class=vcard><span class=fn>Ian
   Hickson</span></span>, <span class=vcard><span class="fn n"><span
   class=given-name>Eric</span> <abbr class=additional-name>A.</abbr> <span
   class=family-name>Meyer</span></span></span>, <span class=vcard><span
   class=fn>Björn Höhrmann</span></span>.

  <h2 id=references><span class=secno>7. </span>References</h2>

  <h3 class=no-num id=normative-references>Normative references</h3>
  <!--begin-normative-->
  <!-- Sorted by label -->

  <dl class=bibliography>
   <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
    <!---->

   <dt id=ref-CSS21>[CSS21]

   <dd>Bert Bos; et al. <a
    href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
    Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
    2011. W3C Recommendation. URL: <a
    href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
   </dd>
   <!---->

   <dt id=ref-RFC2119>[RFC2119]

   <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
    words for use in RFCs to Indicate Requirement Levels.</cite></a> RFC
    2119. URL: <a
    href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
   </dd>
   <!---->
  </dl>
  <!--end-normative-->

  <h3 class=no-num id=informative-references>Informative references</h3>
  <!--begin-informative-->
  <!-- Sorted by label -->

  <dl class=bibliography>
   <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
    <!---->

   <dt id=ref-HTML401>[HTML401]

   <dd>Dave Raggett; Arnaud Le Hors; Ian Jacobs. <a
    href="http://www.w3.org/TR/1999/REC-html401-19991224"><cite>HTML 4.01
    Specification.</cite></a> 24 December 1999. W3C Recommendation. URL: <a
    href="http://www.w3.org/TR/1999/REC-html401-19991224">http://www.w3.org/TR/1999/REC-html401-19991224</a>
   </dd>
   <!---->

   <dt id=ref-SVG11>[SVG11]

   <dd>Erik Dahlström; et al. <a
    href="http://www.w3.org/TR/2011/REC-SVG11-20110816/"><cite>Scalable
    Vector Graphics (SVG) 1.1 (Second Edition).</cite></a> 16 August 2011.
    W3C Recommendation. URL: <a
    href="http://www.w3.org/TR/2011/REC-SVG11-20110816/">http://www.w3.org/TR/2011/REC-SVG11-20110816/</a>
   </dd>
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