css-fonts/Fonts.html@538559084d14
css-fonts/Fonts.html
Wed, 26 Feb 2014 13:10:40 +0900
- author
- John Daggett <jdaggett@mozilla.com>
- date
- Wed, 26 Feb 2014 13:10:40 +0900
- changeset 10069
- 538559084d14
- parent 9209
- 0fd8e74f0ab3
- child 14709
- 0530ba8002d7
- permissions
- -rw-r--r--
[css3-fonts] add an example of font descriptor matching
1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
4 <html lang=en>
5 <head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
7 <title>CSS Fonts Module Level 3</title>
8 <!--
9 FIXME when publishing: copy the current default.css and link to
10 "default.css" rather than "../default.css"
11 -->
12 <link href="../default.css" rel=stylesheet type="text/css">
13 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
14 <!-- I'm just experimenting here, don't get your bee in a bonnet -->
15 <script src="http://use.typekit.com/xon2bky.js"
16 type="text/javascript"></script>
17 <script type="text/javascript">try{Typekit.load();}catch(e){}</script>
19 <style type="text/css">
21 body, th, td, h1, h2, h3, h4, h5, h6 {
22 font-family: "myriad-pro", sans-serif !important;
23 }
25 body {
26 padding: 2em 70px 2em 70px;
27 }
29 p + p, p.mtb {
30 margin-top: 0.8em;
31 text-indent: 0px;
32 }
34 #bolderlighter {
35 width: 40%;
36 }
38 #bolderlighter th {
39 text-align: center;
40 }
42 #fontformats td, #eventhandlers td, #fontformats th, #eventhandlers th {
43 padding-right: 2em;
44 text-align: left;
45 }
47 dd {
48 margin-bottom: 1em;
49 }
51 #authors dd {
52 margin-bottom: 0;
53 }
55 #fontstylematchingalg {
56 list-style-type: lower-alpha;
57 }
59 #fontmatchingalg ul, #fontmatchingalg ol {
60 margin-top: 0.8em;
61 }
63 #fontmatchingalg li + li {
64 margin-top: 0.8em;
65 }
67 div.example {
68 padding: 1em;
69 margin-top: 1em;
70 }
72 div.example + div.example {
73 margin-top: 2em;
74 }
76 div.figure {
77 page-break-inside: avoid;
78 }
80 pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
82 div.featex {
83 width: 700px;
84 }
86 div.featex img {
87 margin: auto;
88 display: block;
89 }
91 span.tag {
92 font-family: monospace;
93 font-size: 120%;
94 }
96 ol ol {
97 list-style-type: lower-alpha;
98 }
100 .idl-code {
101 font-weight: bold;
102 color: #c50;
103 }
104 </style>
105 <link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
106 type="text/css">
107 <script defer=defer
108 src="http://test.csswg.org/harness/annotate.js#CSS3-FONTS_DEV"
109 type="text/javascript"></script>
111 <body>
112 <div class=head> <!--begin-logo-->
113 <p><a href="http://www.w3.org/"><img alt=W3C height=48
114 src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
116 <h1>CSS Fonts Module Level 3</h1>
118 <h2 class="no-num no-toc" id=editors-draft-26-february-2014>Editor's Draft
119 26 February 2014</h2>
121 <dl id=authors>
122 <dt>This version:
124 <dd><a
125 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
126 <!-- <dd><a href="http://www.w3.org/TR/2014/ED-css-fonts-3-20140226/">http://www.w3.org/TR/2014/ED-css-fonts-3-20140226/</a> -->
129 <dt>Latest version:
131 <dd><a
132 href="http://www.w3.org/TR/css-fonts-3/">http://www.w3.org/TR/css-fonts-3/</a>
134 <dt>Latest editor's draft:
136 <dd><a
137 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
138 (<a
139 href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
140 log</a>)
142 <dt>Previous version:
144 <dd><a
145 href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/</a>
147 <dt>Issues List:
149 <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
150 issues in Tracker</a>
152 <dd><a
153 href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&product=CSS&component=Fonts&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED">CSS3
154 Fonts issues in Bugzilla</a>
156 <dt>Discussion:
158 <dd><a
159 href="mailto:www-style@w3.org?subject=%5Bcss-fonts%5D%20feedback">www-style@w3.org</a>
160 with subject line “<kbd>[css-fonts] <var>… message topic
161 …</var></kbd>” (<a
162 href="http://lists.w3.org/Archives/Public/www-style/"
163 rel=discussion>archives</a>)
165 <dt>Test Suite:
167 <dd><a
168 href="http://test.csswg.org/suites/css3-fonts/nightly-unstable/">http://test.csswg.org/suites/css3-fonts/nightly-unstable/</a>
171 <dt>Editor:
173 <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
174 </dl>
175 <!--begin-copyright-->
176 <p class=copyright><a
177 href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
178 rel=license>Copyright</a> © 2014 <a href="http://www.w3.org/"><abbr
179 title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
180 href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
181 Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
182 title="European Research Consortium for Informatics and
183 Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
184 <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
185 <a
186 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
187 <a
188 href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
189 and <a
190 href="http://www.w3.org/Consortium/Legal/copyright-documents">document
191 use</a> rules apply.</p>
192 <!--end-copyright-->
193 <hr title="Separator for header">
194 </div>
196 <h2 class="no-num no-toc" id=abstract>Abstract</h2>
198 <p>This CSS3 module describes how font properties are specified and how
199 font resources are loaded dynamically. The contents of this specification
200 are a consolidation of content previously divided into <a
201 href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
202 and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
203 Web Fonts</a> modules. The description of font load events was moved into
204 the <a href="http://dev.w3.org/csswg/css-font-load-events/">CSS3 Font Load
205 Events</a> module.
207 <h2 class="no-num no-toc" id=status>Status of this document</h2>
208 <!--begin-status-->
210 <p>This is a public copy of the editors' draft. It is provided for
211 discussion only and may change at any moment. Its publication here does
212 not imply endorsement of its contents by W3C. Don't cite this document
213 other than as work in progress.
215 <p>The (<a
216 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
217 mailing list <a
218 href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
219 www-style@w3.org</a> (see <a
220 href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
221 discussion of this specification. When sending e-mail, please put the text
222 “css3-fonts” in the subject, preferably like this:
223 “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
225 <p>This document was produced by the <a
226 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
227 the <a href="http://www.w3.org/Style/">Style Activity</a>).
229 <p>This document was produced by a group operating under the <a
230 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
231 2004 W3C Patent Policy</a>. W3C maintains a <a
232 href="http://www.w3.org/2004/01/pp-impl/32061/status"
233 rel=disclosure>public list of any patent disclosures</a> made in
234 connection with the deliverables of the group; that page also includes
235 instructions for disclosing a patent. An individual who has actual
236 knowledge of a patent which the individual believes contains <a
237 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
238 Claim(s)</a> must disclose the information in accordance with <a
239 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
240 6 of the W3C Patent Policy</a>.</p>
241 <!--end-status-->
243 <p>See the section <a href="#cr-exit-criteria">CR Exit Criteria</a> for
244 details on advancing this specification to W3C Recommendation. The
245 specification will remain Candidate Recommendation at least until 3 April
246 2014. A <a
247 href="http://test.csswg.org/suites/css3-fonts/nightly-unstable/report/">test
248 suite and implementation report</a> are under development.
250 <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
252 <p>The following features are at risk; if interoperable implementations are
253 not found, they may be removed to advance the other features in this
254 specification to Proposed Recommendation:
256 <ul>
257 <li>fallback handling for text decoration in superscript/subscript variant
258 glyphs (‘<a href="#propdef-font-variant-position"><code
259 class=property>font-variant-position</code></a>’)
261 <li>‘<a href="#propdef-font-language-override"><code
262 class=property>font-language-override</code></a>’ property
263 </ul>
265 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
266 <!--begin-toc-->
268 <ul class=toc>
269 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
271 <li><a href="#typography-background"><span class=secno>2 </span>Typography
272 Background</a>
274 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
275 Properties</a>
276 <ul class=toc>
277 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
278 family: the font-family property</a>
279 <ul class=toc>
280 <li><a href="#generic-font-families"><span class=secno>3.1.1
281 </span>Generic font families</a>
282 </ul>
284 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
285 weight: the font-weight property</a>
287 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
288 width: the font-stretch property</a>
290 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
291 the font-style property</a>
293 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
294 the font-size property</a>
296 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
297 </span>Relative sizing: the font-size-adjust property</a>
299 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
300 property: the font property</a>
302 <li><a href="#font-synthesis-prop"><span class=secno>3.8
303 </span>Controlling synthetic faces: the font-synthesis property</a>
304 </ul>
306 <li><a href="#font-resources"><span class=secno>4 </span>Font
307 Resources</a>
308 <ul class=toc>
309 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
310 <code>@font-face</code> rule</a>
312 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
313 family: the font-family descriptor</a>
315 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
316 src descriptor</a>
318 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
319 descriptors: the font-style, font-weight, font-stretch descriptors</a>
321 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
322 range: the unicode-range descriptor</a>
324 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
325 character ranges to define composite fonts</a>
327 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
328 features: the font-variant and font-feature-settings descriptors</a>
330 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
331 loading guidelines</a>
333 <li><a href="#font-fetching-requirements"><span class=secno>4.9
334 </span>Font fetching requirements</a>
335 </ul>
337 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
338 Matching Algorithm</a>
339 <ul class=toc>
340 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
341 sensitivity of font family names</a>
343 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
344 font styles</a>
346 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
347 matching</a>
349 <li><a href="#char-handling-issues"><span class=secno>5.4
350 </span>Character handling issues</a>
352 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
353 matching changes since CSS 2.1</a>
355 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
356 matching examples</a>
357 </ul>
359 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
360 Properties</a>
361 <ul class=toc>
362 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
363 </span>Glyph selection and positioning</a>
365 <li><a href="#language-specific-support"><span class=secno>6.2
366 </span>Language-specific display</a>
368 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
369 the font-kerning property</a>
371 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
372 </span>Ligatures: the font-variant-ligatures property</a>
374 <li><a href="#font-variant-position-prop"><span class=secno>6.5
375 </span>Subscript and superscript forms: the font-variant-position
376 property</a>
378 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
379 </span>Capitalization: the font-variant-caps property</a>
381 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
382 </span>Numerical formatting: the font-variant-numeric property</a>
384 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
385 </span>Alternates and swashes: the font-variant-alternates property</a>
388 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
389 font specific alternates: the <code>@font-feature-values</code>
390 rule</a>
391 <ul class=toc>
392 <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
393 syntax</a>
395 <li><a href="#multi-valued-feature-value-definitions"><span
396 class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
397 </ul>
399 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
400 </span>East Asian text rendering: the font-variant-east-asian
401 property</a>
403 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
404 shorthand for font rendering: the font-variant property</a>
406 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
407 </span>Low-level font feature settings control: the
408 font-feature-settings property</a>
410 <li><a href="#font-language-override-prop"><span class=secno>6.13
411 </span>Font language override: the font-language-override property</a>
412 </ul>
414 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
415 Feature Resolution </a>
416 <ul class=toc>
417 <li><a href="#default-features"><span class=secno>7.1 </span>Default
418 features</a>
420 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
421 precedence</a>
423 <li><a href="#feature-precedence-examples"><span class=secno>7.3
424 </span>Feature precedence examples</a>
425 </ul>
427 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
428 <ul class=toc>
429 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
430 <code>CSSFontFaceRule</code> interface</a>
432 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
433 <code>CSSFontFeatureValuesRule</code> interface</a>
434 </ul>
436 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
437 platform font properties to CSS properties</a>
439 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
440 <ul class=toc>
441 <li class=no-num><a href="#recent-changes"> Changes from the July 2013
442 CSS3 Fonts Last Call Working Draft</a>
443 </ul>
445 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
447 <li class=no-num><a href="#conformance"> Conformance</a>
448 <ul class=toc>
449 <li class=no-num><a href="#conventions"> Document Conventions</a>
451 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
454 <li class=no-num><a href="#partial"> Partial Implementations</a>
456 <li class=no-num><a href="#experimental"> Experimental
457 Implementations</a>
459 <li class=no-num><a href="#testing"> Non-Experimental
460 Implementations</a>
462 <li class=no-num><a href="#cr-exit-criteria">CR Exit Criteria</a>
463 </ul>
465 <li class=no-num><a href="#references">References</a>
466 <ul class=toc>
467 <li class=no-num><a href="#normative-references">Normative
468 References</a>
470 <li class=no-num><a href="#other-references">Other References</a>
471 </ul>
473 <li class=no-num><a href="#index">Index</a>
475 <li class=no-num><a href="#property-index">Property index</a>
476 </ul>
477 <!--end-toc-->
479 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
481 <p>A font provides a resource containing the visual representation of
482 characters. At the simplest level it contains information that maps
483 character codes to shapes (called glyphs) that represent these characters.
484 Fonts sharing a common design style are commonly grouped into font
485 families classified by a set of standard font properties. Within a family,
486 the shape displayed for a given character can vary by stroke weight, slant
487 or relative width, among others. An individual font face is described by a
488 unique combination of these properties. For a given range of text, CSS
489 font properties are used to select a font family and a specific font face
490 within that family to be used when rendering that text. As a simple
491 example, to use the bold form of Helvetica one could use:
493 <pre>body {
494 font-family: Helvetica;
495 font-weight: bold;
496 }</pre>
498 <p>Font resources may be installed locally on the system on which a user
499 agent is running or downloadable. For local font resources descriptive
500 information can be obtained directly from the font resource. For
501 downloadable font resources (sometimes referred to as web fonts), the
502 descriptive information is included with the reference to the font
503 resource.
505 <p>Families of fonts typically don't contain a single face for each
506 possible variation of font properties. The CSS font selection mechanism
507 describes how to match a given set of CSS font properties to a single font
508 face.
510 <h2 id=typography-background><span class=secno>2 </span>Typography
511 Background</h2>
513 <p><em>This section is non-normative.</em>
515 <p> Typographic traditions vary across the globe, so there is no unique way
516 to classify all fonts across languages and cultures. For even common Latin
517 letters, wide variations are possible:
519 <div class=figure><img alt="variations in glyphs for a single character"
520 src=aaaaaa.png>
521 <p class=caption>One character, many glyph variations
522 </div>
524 <p>Differences in the anatomy of letterforms is one way to distinguish
525 fonts. For Latin fonts, flourishes at the ends of a character's main
526 strokes, or serifs, can distinguish a font from those without. Similar
527 comparisons exist in non-Latin fonts between fonts with tapered strokes
528 and those using primarily uniform strokes:
530 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
531 <p class=caption>Letterforms with and without serifs
532 </div>
534 <div class=figure><img alt="serif vs. non-serifs for japanese"
535 src=minchovsgothic.png>
536 <p class=caption>Similar groupings for Japanese typefaces
537 </div>
539 <p>Fonts contain letterforms and the data needed to map characters to these
540 letterforms. Often this may be a simple one-to-one mapping, but more
541 complex mappings are also possible. The use of combining diacritic marks
542 creates many variations for an underlying letterform:
544 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
545 <p class=caption>Variations with diacritic marks
546 </div>
548 <p>A sequence of characters can be represented by a single glyph known as a
549 ligature:
551 <div class=figure><img alt="example of a fi ligature"
552 src=final-ligature.png>
553 <p class=caption>Ligature example
554 </div>
556 <p>Visual transformations based on textual context are often stylistic
557 option in European languages. They are required to correctly render
558 languages like Arabic, the lam and alef characters below <em>must</em> be
559 combined when they exist in sequence:
561 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
562 <p class=caption>Required Arabic ligature
563 </div>
565 <p>The relative complexity of these shaping transformations requires
566 additional data within the font.
568 <p>Sets of font faces with various stylistic variations are often grouped
569 together into font families. In the simplest case a regular face is
570 supplemented with bold and italic faces, but much more extensive groupings
571 are possible. Variations in the thickness of letterform strokes, the <dfn
572 id=weight>weight</dfn>, and the overall proportions of the letterform, the
573 <dfn id=width>width</dfn>, are most common. In the example below, each
574 letter uses a different font face within the Univers font family. The
575 width used increases from top to bottom and the weight increases from left
576 to right:
578 <div class=figure><img alt="various width and weight variations within a
579 single family" src=weightwidthvariations.png>
580 <p class=caption>Weight and width variations within a single font family
581 </div>
583 <p>Creating fonts that support multiple scripts is a difficult task;
584 designers need to understand the cultural traditions surrounding the use
585 of type in different scripts and come up with letterforms that somehow
586 share a common theme. Many languages often share a common script and each
587 of these languages may have noticeable stylistic differences. For example,
588 the Arabic script, when used for Persian and Urdu, exhibits significant
589 and systematic differences in letterforms, as does Cyrillic when used with
590 languages such as Serbian and Russian.
592 <p>The <a href="#character-map"><em>character map</em></a> of a font
593 defines the mapping of characters to glyphs for that font. If a document
594 contains characters not supported by the <a href="#character-map"><em
595 title="character map">character maps</em></a> of the fonts contained in a
596 font family list, a user agent may use a <a
597 href="#system-font-fallback"><em>system font fallback</em></a> procedure
598 to locate an appropriate font that does. If no appropriate font can be
599 found, some form of "missing glyph" character will be rendered by the user
600 agent. System fallback can occur when the specified list of font families
601 does not include a font that supports a given character.
603 <p>Although the <a href="#character-map"><em>character map</em></a> of a
604 font maps a given character to a glyph for that character, modern font
605 technologies such as OpenType and AAT (Apple Advanced Typography) provide
606 ways of mapping a character to different glyphs based upon feature
607 settings. Fonts in these formats allow these features to be embedded in
608 the font itself and controlled by applications. Common typographic
609 features which can be specified this way include ligatures, swashes,
610 contextual alternates, proportional and tabular figures, and automatic
611 fractions, to list just a few. For a visual overview of OpenType features,
612 see the <a href="#OPENTYPE-FONT-GUIDE"
613 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
615 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
617 <p>The particular font face used to render a character is determined by the
618 font family and other font properties that apply to a given element. This
619 structure allows settings to be varied independent of each other.</p>
620 <!-- prop: font-family -->
622 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
623 href="#propdef-font-family">font-family</a> property</h3>
625 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
626 <tbody>
627 <tr>
628 <td>Name:
630 <td><dfn id=propdef-font-family
631 title="font-family!!property">font-family</dfn>
633 <tr>
634 <td>Value:
636 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
637 <a href="#generic-family-value"><var><generic-family></var></a> ]
638 #
640 <tr>
641 <td>Initial:
643 <td>depends on user agent
645 <tr>
646 <td>Applies to:
648 <td>all elements
650 <tr>
651 <td>Inherited:
653 <td>yes
655 <tr>
656 <td>Percentages:
658 <td>N/A
660 <tr>
661 <td>Media:
663 <td>visual
665 <tr>
666 <td>Computed value:
668 <td>as specified
670 <tr>
671 <td>Animatable:
673 <td>no
674 </table>
676 <p>This property specifies a prioritized list of font family names or
677 generic family names. A font family defines a set of faces that vary in
678 weight, width or slope. CSS uses the combination of a family name with
679 other style attributes to select an individual face. Using this selection
680 mechanism, rather than selecting a face via the style name as is often
681 done in design applications, allows some degree of regularity in textual
682 display when fallback occurs.
684 <p class=note>Designers should note that the CSS definition of font
685 attributes used for selection are explicitly not intended to define a font
686 taxonomy. A type designer's idea of a family may often extend to a set of
687 faces that vary along axes other than just the standard axes of weight,
688 width and slope. A family may extend to include both a set of serif faces
689 and a set of sans-serif faces or vary along axes that are unique to that
690 family. The CSS font selection mechanism merely provides a way to
691 determine the “closest” substitute when substitution is necessary.
693 <p>Unlike other CSS properties, component values are a comma-separated list
694 indicating alternatives. A user agent iterates through the list of family
695 names until it matches an available font that contains a glyph for the
696 character to be rendered. This allows for differences in available fonts
697 across platforms and for differences in the range of characters supported
698 by individual fonts.
700 <p>A font family name only specifies a name given to a set of font faces,
701 it does not specify an individual face. For example, given the
702 availability of the fonts below, Futura would match but Futura Medium
703 would not:
705 <div class=figure><img alt="family and face names"
706 src=familyvsfacename.png>
707 <p class=caption>Family and individual face names
708 </div>
710 <p>Consider the example below:
712 <div class=example>
713 <pre>body {
714 font-family: Helvetica, Verdana, sans-serif;
715 }</pre>
717 <p>If Helvetica is available it will be used when rendering. If neither
718 Helvetica nor Verdana is present, then the user-agent-defined sans serif
719 font will be used.</p>
720 </div>
722 <p>There are two types of font family names:
724 <dl>
725 <dt><dfn id=family-name-value><var><family-name></var></dfn>
727 <dd>The name of a font family of choice such as Helvetica or Verdana in
728 the previous example.
730 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
732 <dd> The following generic family keywords are defined: ‘<a
733 href="#serif"><code class=property>serif</code></a>’, ‘<a
734 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
735 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
736 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
737 href="#monospace"><code class=property>monospace</code></a>’. These
738 keywords can be used as a general fallback mechanism when an author's
739 desired font choices are not available. As keywords, they must not be
740 quoted. Authors are encouraged to append a generic font family as a last
741 alternative for improved robustness.
742 </dl>
744 <p>Font family names other than generic families must either be given
745 quoted as <a
746 href="http://www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or
747 unquoted as a sequence of one or more <a
748 href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
749 This means most punctuation characters and digits at the start of each
750 token must be escaped in unquoted font family names.
752 <p>To illustrate this, the following declarations are invalid:
754 <pre>
755 font-family: Red/Black, sans-serif;
756 font-family: "Lucida" Grande, sans-serif;
757 font-family: Ahem!, sans-serif;
758 font-family: test@foo, sans-serif;
759 font-family: #POUND, sans-serif;
760 font-family: Hawaii 5-0, sans-serif;
761 </pre>
763 <p>If a sequence of identifiers is given as a font family name, the
764 computed value is the name converted to a string by joining all the
765 identifiers in the sequence by single spaces.
767 <p>To avoid mistakes in escaping, it is recommended to quote font family
768 names that contain white space, digits, or punctuation characters other
769 than hyphens:
771 <pre>
772 body { font-family: "New Century Schoolbook", serif }
774 <BODY STYLE="font-family: '21st Century', fantasy">
775 </pre>
777 <p>Font family <em>names</em> that happen to be the same as a keyword value
778 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
779 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
780 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
781 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
782 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
783 class=property>cursive</code></a>’) must be quoted to prevent confusion
784 with the keywords with the same names. The keywords ‘<code
785 class=property>initial</code>’ and ‘<code
786 class=property>default</code>’ are reserved for future use and must also
787 be quoted when used as font names. UAs must not consider these keywords as
788 matching the <a
789 href="#family-name-value"><var><family-name></var></a> type.
791 <p>The precise way a set of fonts are grouped into font families varies
792 depending upon the platform font management API's. The Windows GDI API
793 only allows four faces to be grouped into a family while the DirectWrite
794 API and API's on OSX and other platforms support font families with a
795 variety of weights, widths and slopes (see <a
796 href="#platform-props-to-css">Appendix A</a> for more details).
798 <p>Some font formats allow fonts to carry multiple localizations of the
799 family name. User agents must recognize and correctly match all of these
800 names independent of the underlying platform localization, system API used
801 or document encoding:
803 <div class=figure><img alt="examples of localized family names"
804 src=localizedfamilynames.png>
805 <p class=caption>Localized family names
806 </div>
808 <p>The details of localized font family name matching and the corresponding
809 issues of case sensitivity are described below in the <a
810 href="#font-family-casing">font matching</a> section.
812 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
813 families</h4>
815 <p>All five generic font families are defined to exist in all CSS
816 implementations (they need not necessarily map to five distinct actual
817 fonts). User agents should provide reasonable default choices for the
818 generic font families, which express the characteristics of each family as
819 well as possible within the limits allowed by the underlying technology.
820 User agents are encouraged to allow users to select alternative choices
821 for the generic fonts.
823 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
824 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
826 <p>Serif fonts represent the formal text style for a script. This often
827 means but is not limited to glyphs that have finishing strokes, flared or
828 tapering ends, or have actual serifed endings (including slab serifs).
829 Serif fonts are typically proportionately-spaced. They often display a
830 greater variation between thick and thin strokes than fonts from the ‘<a
831 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
832 font family. CSS uses the term ‘<a href="#serif"><code
833 class=property>serif</code></a>’ to apply to a font for any script,
834 although other names may be more familiar for particular scripts, such as
835 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
836 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
837 class=property>serif</code></a>’ more due to its typographic role rather
838 than its actual design style. Any font that is so described may be used to
839 represent the generic ‘<a href="#serif"><code
840 class=property>serif</code></a>’ family.
842 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
843 <p class=caption>Sample serif fonts
844 </div>
846 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
847 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
848 id=sans-serif>sans-serif</dfn></a></span></h5>
850 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
851 low contrast (vertical and horizontal stems have the close to the same
852 thickness) and have stroke endings that are plain -- without any flaring,
853 cross stroke, or other ornamentation. Sans-serif fonts are typically
854 proportionately-spaced. They often have little variation between thick and
855 thin strokes, compared to fonts from the ‘<a href="#serif"><code
856 class=property>serif</code></a>’ family. CSS uses the term ‘<a
857 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
858 to a font for any script, although other names may be more familiar for
859 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
860 (Korean). Any font that is so described may be used to represent the
861 generic ‘<a href="#sans-serif"><code
862 class=property>sans-serif</code></a>’ family.
864 <div class=figure><img alt="sample sans-serif fonts"
865 src=sansserifexamples.png>
866 <p class=caption>Sample sans-serif fonts
867 </div>
869 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
870 title="cursive, definition of"> <a name=cursive-def><dfn
871 id=cursive>cursive</dfn></a></span></h5>
873 <p>Glyphs in cursive fonts generally use a more informal script style, and
874 the result looks more like handwritten pen or brush writing than printed
875 letterwork. CSS uses the term ‘<a href="#cursive"><code
876 class=property>cursive</code></a>’ to apply to a font for any script,
877 although other names such as Chancery, Brush, Swing and Script are also
878 used in font names.
880 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
881 <p class=caption>Sample cursive fonts
882 </div>
884 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
885 title="fantasy, definition of"> <a name=fantasy-def><dfn
886 id=fantasy>fantasy</dfn></a></span></h5>
888 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
889 decorative or expressive representations of characters. These do not
890 include Pi or Picture fonts which do not represent actual characters.
892 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
893 <p class=caption>Sample fantasy fonts
894 </div>
896 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
897 title="monospace, definition of"> <a name=monospace-def><dfn
898 id=monospace>monospace</dfn></a></span></h5>
900 <p>The sole criterion of a monospace font is that all glyphs have the same
901 fixed width. This is often used to render samples of computer code.
903 <div class=figure><img alt="sample monospace fonts"
904 src=monospaceexamples.png>
905 <p class=caption>Sample monospace fonts
906 </div>
907 <!-- prop: font-weight -->
909 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
910 href="#propdef-font-weight">font-weight</a> property</h3>
912 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
913 <tbody>
914 <tr>
915 <td>Name:
917 <td><dfn id=propdef-font-weight
918 title="font-weight!!property">font-weight</dfn>
920 <tr>
921 <td>Value:
923 <td><a href="#font-weight-normal-value"
924 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
925 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
926 href="#font-weight-numeric-values" title="100...900 weight
927 values">100</a> | <a href="#font-weight-numeric-values"
928 title="100...900 weight values">200</a> | <a
929 href="#font-weight-numeric-values" title="100...900 weight
930 values">300</a> | <a href="#font-weight-numeric-values"
931 title="100...900 weight values">400</a> | <a
932 href="#font-weight-numeric-values" title="100...900 weight
933 values">500</a> | <a href="#font-weight-numeric-values"
934 title="100...900 weight values">600</a> | <a
935 href="#font-weight-numeric-values" title="100...900 weight
936 values">700</a> | <a href="#font-weight-numeric-values"
937 title="100...900 weight values">800</a> | <a
938 href="#font-weight-numeric-values" title="100...900 weight
939 values">900</a>
941 <tr>
942 <td>Initial:
944 <td>normal
946 <tr>
947 <td>Applies to:
949 <td>all elements
951 <tr>
952 <td>Inherited:
954 <td>yes
956 <tr>
957 <td>Percentages:
959 <td>N/A
961 <tr>
962 <td>Media:
964 <td>visual
966 <tr>
967 <td>Computed value:
969 <td>numeric weight value (see description)
971 <tr>
972 <td>Animatable:
974 <td>as <a
975 href="http://dev.w3.org/csswg/css-transitions/#animtype-font-weight">font
976 weight</a>
977 </table>
979 <p>The <a href="#propdef-font-weight"
980 title="font-weight!!property">‘<code
981 class=property>font-weight</code>’</a> property specifies the weight of
982 glyphs in the font, their degree of blackness or stroke thickness.
984 <p>Values have the following meanings:
986 <dl>
987 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
988 to 900</dfn>
990 <dd>These values form an ordered sequence, where each number indicates a
991 weight that is at least as dark as its predecessor. These roughly
992 correspond to the commonly used weight names below:
993 </dl>
995 <ul>
996 <li>100 - Thin
998 <li>200 - Extra Light (Ultra Light)
1000 <li>300 - Light
1002 <li>400 - Normal
1004 <li>500 - Medium
1006 <li>600 - Semi Bold (Demi Bold)
1008 <li>700 - Bold
1010 <li>800 - Extra Bold (Ultra Bold)
1012 <li>900 - Black (Heavy)
1013 </ul>
1015 <dl>
1016 <dt><dfn id=font-weight-normal-value
1017 title="normal!!font-weight">normal</dfn>
1019 <dd>Same as ‘<code class=css>400</code>’.
1021 <dt><dfn id=bold>bold</dfn>
1023 <dd>Same as ‘<code class=css>700</code>’.
1025 <dt><dfn id=bolder>bolder</dfn>
1027 <dd>Specifies a bolder weight than the inherited value.
1029 <dt><dfn id=lighter>lighter</dfn>
1031 <dd>Specifies a lighter weight than the inherited value.
1032 </dl>
1034 <p>Font formats that use a scale other than a nine-step scale should map
1035 their scale onto the CSS scale so that 400 roughly corresponds with a face
1036 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1037 face that would be labeled as Bold. Or weights may be inferred from the
1038 style names, ones that correspond roughly with the scale above. The scale
1039 is relative, so a face with a larger weight value must never appear
1040 lighter. If style names are used to infer weights, care should be taken to
1041 handle variations in style names across locales.
1043 <p>Quite often there are only a few weights available for a particular font
1044 family. When a weight is specified for which no face exists, a face with a
1045 nearby weight is used. In general, bold weights map to faces with heavier
1046 weights and light weights map to faces with lighter weights (see the <a
1047 href="#font-matching-algorithm">font matching section below</a> for a
1048 precise definition). The examples here illustrate which face is used for
1049 different weights, grey indicates a face for that weight does not exist so
1050 a face with a nearby weight is used:
1052 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1053 900 weights" src=optimaweights.png>
1054 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1055 weight faces
1056 </div>
1058 <div class=figure><img alt="weight mappings for a family with 300, 600
1059 weights" src=hiraginoweights.png>
1060 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1061 faces
1062 </div>
1064 <p>Although the practice is not well-loved by typographers, bold faces are
1065 often synthesized by user agents for faces that lack actual bold faces.
1066 For the purposes of style matching, these faces must be treated as if they
1067 exist within the family. Authors can explicitly avoid this behavior by
1068 using the ‘<a href="#propdef-font-synthesis"><code
1069 class=property>font-synthesis</code></a>’ property.
1071 <p>Specified values of ‘<a href="#bolder"><code
1072 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1073 class=property>lighter</code></a>’ indicate weights relative to the
1074 weight of the parent element. The computed weight is calculated based on
1075 the inherited <a href="#propdef-font-weight"
1076 title="font-weight!!property">‘<code
1077 class=property>font-weight</code>’</a> value using the chart below.
1079 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1080 <thead>
1081 <tr>
1082 <th>Inherited value
1084 <th>bolder
1086 <th>lighter
1088 <tbody>
1089 <tr>
1090 <th>100
1092 <td>400
1094 <td>100
1096 <tr>
1097 <th>200
1099 <td>400
1101 <td>100
1103 <tr>
1104 <th>300
1106 <td>400
1108 <td>100
1110 <tr>
1111 <th>400
1113 <td>700
1115 <td>100
1117 <tr>
1118 <th>500
1120 <td>700
1122 <td>100
1124 <tr>
1125 <th>600
1127 <td>900
1129 <td>400
1131 <tr>
1132 <th>700
1134 <td>900
1136 <td>400
1138 <tr>
1139 <th>800
1141 <td>900
1143 <td>700
1145 <tr>
1146 <th>900
1148 <td>900
1150 <td>700
1151 </table>
1153 <p>The table above is equivalent to selecting the next relative bolder or
1154 lighter face, given a font family containing normal and bold faces along
1155 with a thin and a heavy face. Authors who desire finer control over the
1156 exact weight values used for a given element may use numerical values
1157 instead of relative weights.</p>
1158 <!-- prop: font-stretch -->
1160 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1161 href="#propdef-font-stretch">font-stretch</a> property</h3>
1163 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1164 <tbody>
1165 <tr>
1166 <td>Name:
1168 <td><dfn id=propdef-font-stretch
1169 title="font-stretch!!property">font-stretch</dfn>
1171 <tr>
1172 <td>Value:
1174 <td> <a href="#font-stretch-normal-value"
1175 title="normal!!font-stretch">normal</a> | <a
1176 href="#ultra-condensed">ultra-condensed</a> | <a
1177 href="#extra-condensed">extra-condensed</a> | <a
1178 href="#condensed">condensed</a> | <a
1179 href="#semi-condensed-">semi-condensed</a> | <a
1180 href="#semi-expanded">semi-expanded</a> | <a
1181 href="#expanded">expanded</a> | <a
1182 href="#extra-expanded">extra-expanded</a> | <a
1183 href="#ultra-expanded">ultra-expanded</a>
1185 <tr>
1186 <td>Initial:
1188 <td>normal
1190 <tr>
1191 <td>Applies to:
1193 <td>all elements
1195 <tr>
1196 <td>Inherited:
1198 <td>yes
1200 <tr>
1201 <td>Percentages:
1203 <td>N/A
1205 <tr>
1206 <td>Media:
1208 <td>visual
1210 <tr>
1211 <td>Computed value:
1213 <td>as specified
1215 <tr>
1216 <td>Animatable:
1218 <td>as <a href="#font-stretch-animation">font stretch</a>
1219 </table>
1221 <p>The <a href="#propdef-font-stretch"
1222 title="font-stretch!!property">‘<code
1223 class=property>font-stretch</code>’</a> property selects a normal,
1224 condensed, or expanded face from a font family. Absolute keyword values
1225 have the following ordering, from narrowest to widest:
1227 <ul>
1228 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1230 <li><dfn id=extra-condensed>extra-condensed</dfn>
1232 <li><dfn id=condensed>condensed</dfn>
1234 <li><dfn id=semi-condensed->semi-condensed </dfn>
1236 <li><dfn id=font-stretch-normal-value
1237 title="normal!!font-stretch">normal</dfn>
1239 <li><dfn id=semi-expanded>semi-expanded</dfn>
1241 <li><dfn id=expanded>expanded</dfn>
1243 <li><dfn id=extra-expanded>extra-expanded</dfn>
1245 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1246 </ul>
1248 <p>When a face does not exist for a given width, normal or condensed values
1249 map to a narrower face, otherwise a wider face. Conversely, expanded
1250 values map to a wider face, otherwise a narrower face. The figure below
1251 shows how the nine font-stretch property settings affect font selection
1252 for font family containing a variety of widths, grey indicates a width for
1253 which no face exists and a different width is substituted:
1255 <div class=figure><img alt="width mappings for a family with condensed,
1256 normal and expanded faces" src=universwidths.png>
1257 <p class=caption>Width mappings for a font family with condensed, normal
1258 and expanded width faces
1259 </div>
1261 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1262 interpolated in discrete steps. The interpolation happens as though the
1263 ordered values are equally spaced real numbers. The interpolation result
1264 is rounded to the nearest value, with values exactly halfway between two
1265 values rounded towards the later value in the list above.</p>
1266 <!-- prop: font-style -->
1268 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1269 href="#propdef-font-style">font-style</a> property</h3>
1271 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1272 <tbody>
1273 <tr>
1274 <td>Name:
1276 <td><dfn id=propdef-font-style
1277 title="font-style!!property">font-style</dfn>
1279 <tr>
1280 <td>Value:
1282 <td><a href="#font-style-normal-value"
1283 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1284 <a href="#oblique">oblique</a>
1286 <tr>
1287 <td>Initial:
1289 <td>normal
1291 <tr>
1292 <td>Applies to:
1294 <td>all elements
1296 <tr>
1297 <td>Inherited:
1299 <td>yes
1301 <tr>
1302 <td>Percentages:
1304 <td>N/A
1306 <tr>
1307 <td>Media:
1309 <td>visual
1311 <tr>
1312 <td>Computed value:
1314 <td>as specified
1316 <tr>
1317 <td>Animatable:
1319 <td>no
1320 </table>
1322 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1323 class=property>font-style</code>’</a> property allows italic or oblique
1324 faces to be selected. Italic forms are generally cursive in nature while
1325 oblique faces are typically sloped versions of the regular face. Oblique
1326 faces can be simulated by artificially sloping the glyphs of the regular
1327 face. Compare the artificially sloped renderings of Palatino ‘<code
1328 class=property>a</code>’ and Baskerville ‘<code
1329 class=property>N</code>’ in grey with the actual italic versions:
1331 <div class=figure><img alt="artificial sloping vs. real italics"
1332 src=realvsfakeitalics.png>
1333 <p class=caption>Artificial sloping versus real italics
1334 </div>
1336 <p>Values have the following meanings:
1338 <dl>
1339 <dt><dfn id=font-style-normal-value
1340 title="normal!!font-style">normal</dfn>
1342 <dd>selects a face that is classified as a normal face, one that is
1343 neither italic or obliqued
1345 <dt><dfn id=italic>italic</dfn>
1347 <dd>selects a font that is labeled as an italic face, or an oblique face
1348 if one is not
1350 <dt><dfn id=oblique>oblique</dfn>
1352 <dd>selects a font that is labeled as an oblique face, or an italic face
1353 if one is not
1354 </dl>
1356 <p>If no italic or oblique face is available, oblique faces can be
1357 synthesized by rendering non-obliqued faces with an artificial obliquing
1358 operation. The use of these artificially obliqued faces can be disabled
1359 using the ‘<a href="#propdef-font-synthesis"><code
1360 class=property>font-synthesis</code></a>’ property. The details of the
1361 obliquing operation are not explicitly defined.
1363 <p class=note>Authors should also be aware that synthesized approaches may
1364 not be suitable for scripts like Cyrillic, where italic forms are very
1365 different in shape. It is always better to use an actual italic font
1366 rather than rely on a synthetic version.</p>
1367 <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
1369 <p>Many scripts lack the tradition of mixing a cursive form within text
1370 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1371 always lack italic or oblique faces. Fonts that support a mixture of
1372 scripts will sometimes omit specific scripts such as Arabic from the set
1373 of glyphs supported in the italic face. User agents should be careful
1374 about making <a href="#character-map"><em>character map</em></a>
1375 assumptions across faces when implementing support for <a
1376 href="#system-font-fallback"><em>system font fallback</em></a>.</p>
1377 <!-- prop: font-size -->
1379 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1380 href="#propdef-font-size">font-size</a> property</h3>
1382 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1383 <tbody>
1384 <tr>
1385 <td>Name:
1387 <td><dfn id=propdef-font-size>font-size</dfn>
1389 <tr>
1390 <td>Value:
1392 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1393 | <a href="#relative-size-value"><var><relative-size></var></a> |
1394 <a href="#length-size-value"><var><length></var></a> | <a
1395 href="#percentage-size-value"><var><percentage></var></a>
1397 <tr>
1398 <td>Initial:
1400 <td>medium
1402 <tr>
1403 <td>Applies to:
1405 <td>all elements
1407 <tr>
1408 <td>Inherited:
1410 <td>yes
1412 <tr>
1413 <td>Percentages:
1415 <td>refer to parent element's font size
1417 <tr>
1418 <td>Media:
1420 <td>visual
1422 <tr>
1423 <td>Computed value:
1425 <td>absolute length
1427 <tr>
1428 <td>Animatable:
1430 <td>as <a
1431 href="http://dev.w3.org/csswg/css-transitions/#animtype-length">length</a>
1432 </table>
1434 <p>This property indicates the desired height of glyphs from the font. For
1435 scalable fonts, the font-size is a scale factor applied to the EM unit of
1436 the font. (Note that certain glyphs may bleed outside their EM box.) For
1437 non-scalable fonts, the font-size is converted into absolute units and
1438 matched against the declared font-size of the font, using the same
1439 absolute coordinate space for both of the matched values. Values have the
1440 following meanings:
1442 <dl>
1443 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1445 <dd> An <a
1446 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1447 refers to an entry in a table of font sizes computed and kept by the user
1448 agent. Possible values are:
1449 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1451 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1453 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1454 keyword is interpreted relative to the table of font sizes and the
1455 computed ‘<a href="#propdef-font-size"><code
1456 class=property>font-size</code></a>’ of the parent element. Possible
1457 values are:
1458 <p> [ larger | smaller ]
1460 <p> For example, if the parent element has a font size of ‘<code
1461 class=property>medium</code>’, a value of ‘<code
1462 class=property>larger</code>’ will make the font size of the current
1463 element be ‘<code class=property>large</code>’. If the parent
1464 element's size is not close to a table entry, the user agent is free to
1465 interpolate between table entries or round off to the closest one. The
1466 user agent may have to extrapolate table values if the numerical value
1467 goes beyond the keywords.
1469 <dt><dfn id=length-size-value><var><length></var></dfn>
1471 <dd>A length value specifies an absolute font size (independent of the
1472 user agent's font table). Negative lengths are illegal.
1474 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1476 <dd>A percentage value specifies an absolute font size relative to the
1477 parent element's font size. Use of percentage values, or values in
1478 ‘<code class=property>em</code>’s, leads to more robust and
1479 cascadable style sheets.
1480 </dl>
1482 <p>The following table provides user agent guidelines for the absolute-size
1483 scaling factor and their mapping to HTML heading and absolute font-sizes.
1484 The ‘<code class=property>medium</code>’ value is used as the
1485 reference middle value. The user agent may fine-tune these values for
1486 different fonts or different types of display devices.
1488 <table class=data>
1489 <thead>
1490 <tr>
1491 <th>CSS absolute-size values
1493 <th>xx-small
1495 <th>x-small
1497 <th>small
1499 <th>medium
1501 <th>large
1503 <th>x-large
1505 <th>xx-large
1507 <th>
1509 <tbody>
1510 <tr>
1511 <th>scaling factor
1513 <td>3/5
1515 <td>3/4
1517 <td>8/9
1519 <td>1
1521 <td>6/5
1523 <td>3/2
1525 <td>2/1
1527 <td>3/1
1529 <tr>
1530 <th>HTML headings
1532 <td>h6
1534 <td>
1536 <td>h5
1538 <td>h4
1540 <td>h3
1542 <td>h2
1544 <td>h1
1546 <td>
1548 <tr>
1549 <th>HTML font sizes
1551 <td>1
1553 <td>
1555 <td>2
1557 <td>3
1559 <td>4
1561 <td>5
1563 <td>6
1565 <td>7
1566 </table>
1568 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1569 applying these guidelines should nevertheless avoid creating font-size
1570 resulting in less than 9 device pixels per EM unit on a computer
1571 display.</em>
1573 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1574 factor between adjacent indexes was 1.5 which user experience proved to be
1575 too large. In CSS2, the suggested scaling factor for computer screen
1576 between adjacent indexes was 1.2 which still created issues for the small
1577 sizes. The new scaling factor varies between each index to provide a
1578 better readability.</em>
1580 <p>The actual value of this property may differ from the computed value due
1581 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1582 class=property>font-size-adjust</code></a>’ and the unavailability of
1583 certain font sizes.
1585 <p>Child elements inherit the computed <a class=noxref
1586 href="#font-size-prop"> <span class=property>‘<code
1587 class=property>font-size</code>’</span></a> value (otherwise, the effect
1588 of <a class=noxref href="#font-size-adjust-prop"><span
1589 class=property>‘<code
1590 class=property>font-size-adjust</code>’</span></a> would compound).
1592 <div class=example>
1593 <p style="display:none">Example(s):</p>
1595 <pre>p { font-size: 12pt; }
1596 blockquote { font-size: larger }
1597 em { font-size: 150% }
1598 em { font-size: 1.5em }
1599 </pre>
1600 </div>
1601 <!-- prop: font-size-adjust -->
1603 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1604 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1606 <table class=propdef id=namefont-size-adjustvaluenone-ltnumbergt>
1607 <tbody>
1608 <tr>
1609 <td>Name:
1611 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1613 <tr>
1614 <td>Value:
1616 <td><a href="#font-size-adjust-none-value"
1617 title="none!!font-size-adjust">none</a> | <a
1618 href="#aspect-ratio-value"><var><number></var></a>
1620 <tr>
1621 <td>Initial:
1623 <td>none
1625 <tr>
1626 <td>Applies to:
1628 <td>all elements
1630 <tr>
1631 <td>Inherited:
1633 <td>yes
1635 <tr>
1636 <td>Percentages:
1638 <td>N/A
1640 <tr>
1641 <td>Media:
1643 <td>visual
1645 <tr>
1646 <td>Computed value:
1648 <td>as specified
1650 <tr>
1651 <td>Animatable:
1653 <td>as <a
1654 href="http://dev.w3.org/csswg/css-transitions/#animtype-number">number</a>
1655 </table>
1657 <p>For any given font size, the apparent size and legibility of text varies
1658 across fonts. For scripts such as Latin or Cyrillic that distinguish
1659 between upper and lowercase letters, the relative height of lowercase
1660 letters compared to their uppercase counterparts is a determining factor
1661 of legibility. This is commonly referred to as the <a class=index-def
1662 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1663 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1664 the x-height of a font divided by the font size.
1666 <p>In situations where font fallback occurs, fallback fonts may not share
1667 the same aspect value as the desired font family and will thus appear less
1668 readable. The ‘<a href="#propdef-font-size-adjust"><code
1669 class=property>font-size-adjust</code></a>’ property is a way to
1670 preserve the readability of text when font fallback occurs. It does this
1671 by adjusting the font-size so that the x-height is the same regardless of
1672 the font used.
1674 <div class=example>
1675 <p>The style defined below defines Verdana as the desired font family, but
1676 if Verdana is not available Futura or Times will be used.</p>
1678 <pre>p {
1679 font-family: Verdana, Futura, Times;
1680 }
1682 <p>Lorem ipsum dolor sit amet, ...</p>
1683 </pre>
1685 <p>Verdana has a relatively high aspect value, lowercase letters are
1686 relatively tall compared to uppercase letters, so at small sizes text
1687 appears legible. Times has a lower aspect value and so if fallback
1688 occurs, the text will be less legible at small sizes than Verdana.</p>
1689 </div>
1691 <p>How text rendered in each of these fonts compares is shown below, the
1692 columns show text rendered in Verdana, Futura and Times. The same
1693 font-size value is used across cells within each row and red lines are
1694 included to show the differences in x-height. In the upper half each row
1695 is rendered in the same font-size value. The same is true for the lower
1696 half but in this half the ‘<a href="#propdef-font-size-adjust"><code
1697 class=property>font-size-adjust</code></a>’ property is also set so that
1698 the actual font size is adjusted to preserve the x-height across each row.
1699 Note how small text remains relatively legible across each row in the
1700 lower half.
1702 <div class=figure><img alt="text with and without 'font-size-adjust'"
1703 src=fontsizeadjust.png>
1704 <p class=caption>Text with and without the use of ‘<a
1705 href="#propdef-font-size-adjust"><code
1706 class=property>font-size-adjust</code></a>’
1707 </div>
1709 <p>This property allows authors to specify an <a
1710 href="#aspect-value"><i>aspect value</i></a> for an element that will
1711 effectively preserve the x-height of the first choice font, whether it is
1712 substituted or not. Values have the following meanings:
1714 <dl>
1715 <dt><dfn id=font-size-adjust-none-value
1716 title="none!!font-size-adjust">none</dfn>
1718 <dd>Do not preserve the font's x-height.
1720 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1722 <dd>Specifies the <a href="#aspect-value"><i>aspect value</i></a> used in
1723 the calculation below to calculate the adjusted font size:
1724 <pre>c = ( a / a' ) s
1725 </pre>
1727 <p>where:</p>
1729 <pre>s = font-size value
1730 a = <a href="#aspect-value"><i>aspect value</i></a> as specified by the 'font-size-adjust' property
1731 a' = <a href="#aspect-value"><i>aspect value</i></a> of actual font
1732 c = adjusted font-size to use
1733 </pre>
1735 <p>This value applies to any font that is selected but in typical usage
1736 it should be based on the <a href="#aspect-value"><i>aspect
1737 value</i></a> of the first font in the font-family list. If this is
1738 specified accurately, the <tt>(a/a')</tt> term in the formula above is
1739 effectively 1 for the first font and no adjustment occurs. If the value
1740 is specified inaccurately, text rendered using the first font in the
1741 family list will display differently in older user agents that don't
1742 support ‘<a href="#propdef-font-size-adjust"><code
1743 class=property>font-size-adjust</code></a>’.</p>
1744 </dl>
1746 <p>The value of ‘<a href="#propdef-font-size-adjust"><code
1747 class=property>font-size-adjust</code></a>’ affects the used value of
1748 ‘<a href="#propdef-font-size"><code
1749 class=property>font-size</code></a>’ but does not affect the computed
1750 value. It affects the size of relative units that are based on font
1751 metrics of the <a href="#first-available-font"><i>first available
1752 font</i></a> such as <code>ex</code> and <code>ch</code> but does not
1753 affect the size of <code>em</code> units. Since numeric values of <a
1754 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1755 class=property>line-height</code>’</a> refer to the computed size of
1756 ‘<a href="#propdef-font-size"><code
1757 class=property>font-size</code></a>’, ‘<a
1758 href="#propdef-font-size-adjust"><code
1759 class=property>font-size-adjust</code></a>’ does not affect the used
1760 value of <a
1761 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1762 class=property>line-height</code>’</a>.
1764 <p class=note>In CSS, authors often specify <a
1765 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1766 class=property>line-height</code>’</a> as a multiple of the ‘<a
1767 href="#propdef-font-size"><code class=property>font-size</code></a>’.
1768 Since the ‘<a href="#propdef-font-size-adjust"><code
1769 class=property>font-size-adjust</code></a>’ property affects the used
1770 value of ‘<a href="#propdef-font-size"><code
1771 class=property>font-size</code></a>’, authors should take care setting
1772 the line height when ‘<a href="#propdef-font-size-adjust"><code
1773 class=property>font-size-adjust</code></a>’ is used. Setting the line
1774 height too tightly can result in overlapping lines of text in this
1775 situation.
1777 <p>Authors can calculate the <a href="#aspect-value"><i>aspect
1778 value</i></a> for a given font by comparing spans with the same content
1779 but different ‘<a href="#propdef-font-size-adjust"><code
1780 class=property>font-size-adjust</code></a>’ properties. If the same
1781 font-size is used, the spans will match when the ‘<a
1782 href="#propdef-font-size-adjust"><code
1783 class=property>font-size-adjust</code></a>’ value is accurate for the
1784 given font.
1786 <div class=example>
1787 <p>Two spans with borders are used to determine the <a
1788 href="#aspect-value"><i>aspect value</i></a> of a font. The ‘<a
1789 href="#propdef-font-size"><code class=property>font-size</code></a>’ is
1790 the same for both spans but the ‘<a
1791 href="#propdef-font-size-adjust"><code
1792 class=property>font-size-adjust</code></a>’ property is specified only
1793 for the right span. Starting with a value of 0.5, the aspect value can be
1794 adjusted until the borders around the two letters line up.</p>
1796 <pre>p {
1797 font-family: Futura;
1798 font-size: 500px;
1799 }
1801 span {
1802 border: solid 1px red;
1803 }
1805 .adjust {
1806 font-size-adjust: 0.5;
1807 }
1809 <p><span>b</span><span class="adjust">b</span></p>
1810 </pre>
1812 <div class=figure><img alt="Futura with an <i>aspect value</i> of 0.5"
1813 src=beforefontsizeadjust.png>
1814 <p class=caption>Futura with an <a href="#aspect-value"><i>aspect
1815 value</i></a> of 0.5
1816 </div>
1818 <p>The box on the right is a bit bigger than the one on the left, so the
1819 <a href="#aspect-value"><i>aspect value</i></a> of this font is something
1820 less than 0.5. Adjust the value until the boxes align.</p>
1821 </div>
1822 <!-- prop: font -->
1824 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1825 <a href="#propdef-font">font</a> property</h3>
1827 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1828 <tbody>
1829 <tr>
1830 <td>Name:
1832 <td><dfn id=propdef-font>font</dfn>
1834 <tr>
1835 <td>Value:
1837 <td>[ [ <var><<a href="#propdef-font-style"
1838 title="font-style!!property">‘<code
1839 class=property>font-style</code>’</a>></var> || <a
1840 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1841 || <var><<a href="#propdef-font-weight"
1842 title="font-weight!!property">‘<code
1843 class=property>font-weight</code>’</a>></var> || <var><<a
1844 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1845 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1846 href="#propdef-font-size"><code
1847 class=property>font-size</code></a>’></var> [ / <var><‘<code
1848 class=property>line-height</code>’></var> ]? <var><<a
1849 href="#propdef-font-family" title="font-family!!property">‘<code
1850 class=property>font-family</code>’</a>></var> ] | caption | icon |
1851 menu | message-box | small-caption | status-bar
1853 <tr>
1854 <td>Initial:
1856 <td>see individual properties
1858 <tr>
1859 <td>Applies to:
1861 <td>all elements
1863 <tr>
1864 <td>Inherited:
1866 <td>yes
1868 <tr>
1869 <td>Percentages:
1871 <td>see individual properties
1873 <tr>
1874 <td>Media:
1876 <td>visual
1878 <tr>
1879 <td>Computed value:
1881 <td>see individual properties
1883 <tr>
1884 <td>Animatable:
1886 <td>see individual properties
1887 </table>
1889 <p>The <span class=property>‘<a href="#propdef-font"><code
1890 class=property>font</code></a>’</span> property is, except as described
1891 below, a shorthand property for setting <a href="#propdef-font-style"
1892 title="font-style!!property">‘<code
1893 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1894 title="font-variant!!property">‘<code
1895 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1896 title="font-weight!!property">‘<code
1897 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1898 title="font-stretch!!property">‘<code
1899 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1900 href="#propdef-font-size"><code
1901 class=property>font-size</code></a>’</span>, <a class=property
1902 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1903 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1904 title="font-family!!property">‘<code
1905 class=property>font-family</code>’</a> at the same place in the
1906 stylesheet. Values for the <a href="#propdef-font-variant"
1907 title="font-variant!!property">‘<code
1908 class=property>font-variant</code>’</a> property may also be included
1909 but only those supported in CSS 2.1, none of the <a
1910 href="#propdef-font-variant" title="font-variant!!property">‘<code
1911 class=property>font-variant</code>’</a> values added in this
1912 specification can be used in the <span class=property>‘<a
1913 href="#propdef-font"><code class=property>font</code></a>’</span>
1914 shorthand:
1916 <pre
1917 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1919 <p>The syntax of this property is based on a traditional typographical
1920 shorthand notation to set multiple properties related to fonts.
1922 <p>All subproperties of the ‘<a href="#propdef-font"><code
1923 class=property>font</code></a>’ property are first reset to their
1924 initial values, including those listed above plus <span
1925 class=property>‘<a href="#propdef-font-size-adjust"><code
1926 class=property>font-size-adjust</code></a>’</span>, <span
1927 class=property>‘<a href="#propdef-font-kerning"><code
1928 class=property>font-kerning</code></a>’</span>, subproperties of <a
1929 href="#propdef-font-variant" title="font-variant!!property">‘<code
1930 class=property>font-variant</code>’</a> and and <span>‘<a
1931 href="#propdef-font-language-override"><code
1932 class=property>font-language-override</code></a>’</span>. Then, those
1933 properties that are given explicit values in the <span
1934 class=property>‘<a href="#propdef-font"><code
1935 class=property>font</code></a>’</span> shorthand are set to those
1936 values. For a definition of allowed and initial values, see the previously
1937 defined properties. For reasons of backwards compatibility, it is not
1938 possible to set <span class=property>‘<a
1939 href="#propdef-font-size-adjust"><code
1940 class=property>font-size-adjust</code></a>’</span> to anything other
1941 than its initial value using the <span class=property>‘<a
1942 href="#propdef-font"><code class=property>font</code></a>’</span>
1943 shorthand property; instead, use the individual property.
1945 <div class=example>
1946 <p style="display:none">Example(s):</p>
1948 <pre>p { font: 12pt/14pt sans-serif }
1949 p { font: 80% sans-serif }
1950 p { font: x-large/110% "new century schoolbook", serif }
1951 p { font: bold italic large Palatino, serif }
1952 p { font: normal small-caps 120%/120% fantasy }
1953 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1954 </pre>
1956 <p> In the second rule, the font size percentage value (‘<code
1957 class=css>80%</code>’) refers to the computed ‘<a
1958 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1959 the parent element. In the third rule, the line height percentage
1960 (‘<code class=css>110%</code>’) refers to the font size of the
1961 element itself.
1963 <p>The first three rules do not specify the <a
1964 href="#propdef-font-variant" title="font-variant!!property">‘<code
1965 class=property>font-variant</code>’</a> and <a
1966 href="#propdef-font-weight" title="font-weight!!property">‘<code
1967 class=property>font-weight</code>’</a> explicitly, so these properties
1968 receive their initial values (<span title="normal value">‘<code
1969 class=property>normal</code>’</span>). Notice that the font family name
1970 "new century schoolbook", which contains spaces, is enclosed in quotes.
1971 The fourth rule sets the <a href="#propdef-font-weight"
1972 title="font-weight!!property">‘<code
1973 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1974 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1975 title="font-style!!property">‘<code
1976 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1977 class=property>italic</code></a>’, and implicitly sets <a
1978 href="#propdef-font-variant" title="font-variant!!property">‘<code
1979 class=property>font-variant</code>’</a> to <a
1980 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1981 class=property>normal</code>’</a>.
1983 <p> The fifth rule sets the <a href="#propdef-font-variant"
1984 title="font-variant!!property">‘<code
1985 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1986 class=property>small-caps</code></a>’), the <span class=property>‘<a
1987 href="#propdef-font-size"><code
1988 class=property>font-size</code></a>’</span> (120% of the parent's font
1989 size), the <a class=property
1990 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1991 class=property>line-height</code>’</a> (120% of the font size) and the
1992 <a href="#propdef-font-family" title="font-family!!property">‘<code
1993 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1994 class=property>fantasy</code></a>’). It follows that the keyword <span
1995 title="normal value">‘<code class=property>normal</code>’</span>
1996 applies to the two remaining properties: <a href="#propdef-font-style"
1997 title="font-style!!property">‘<code
1998 class=property>font-style</code>’</a> and <a
1999 href="#propdef-font-weight" title="font-weight!!property">‘<code
2000 class=property>font-weight</code>’</a>.
2002 <p>The sixth rule sets the <a href="#propdef-font-style"
2003 title="font-style!!property">‘<code
2004 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
2005 title="font-stretch!!property">‘<code
2006 class=property>font-stretch</code>’</a>, <span class=property>‘<a
2007 href="#propdef-font-size"><code
2008 class=property>font-size</code></a>’</span>, and <a
2009 href="#propdef-font-family" title="font-family!!property">‘<code
2010 class=property>font-family</code>’</a>, the other font properties being
2011 set to their initial values.
2012 </div>
2014 <p>Since the <a href="#propdef-font-stretch"
2015 title="font-stretch!!property">‘<code
2016 class=property>font-stretch</code>’</a> property was not defined in CSS
2017 2.1, when using <a href="#propdef-font-stretch"
2018 title="font-stretch!!property">‘<code
2019 class=property>font-stretch</code>’</a> values within ‘<a
2020 href="#propdef-font"><code class=property>font</code></a>’ rules,
2021 authors should include a extra version compatible with older user agents:
2023 <pre>p {
2024 font: 80% sans-serif; /* for older user agents */
2025 font: condensed 80% sans-serif;
2026 }</pre>
2028 <p>The following values refer to system fonts:
2030 <dl>
2031 <dt><strong>caption</strong>
2033 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
2034 etc.).
2036 <dt><strong>icon</strong>
2038 <dd>The font used to label icons.
2040 <dt><strong>menu</strong>
2042 <dd>The font used in menus (e.g., dropdown menus and menu lists).
2044 <dt><strong>message-box</strong>
2046 <dd>The font used in dialog boxes.
2048 <dt><strong>small-caption</strong>
2050 <dd>The font used for labeling small controls.
2052 <dt><strong>status-bar</strong>
2054 <dd>The font used in window status bars.
2055 </dl>
2057 <p>System fonts may only be set as a whole; that is, the font family, size,
2058 weight, style, etc. are all set at the same time. These values may then be
2059 altered individually if desired. If no font with the indicated
2060 characteristics exists on a given platform, the user agent should either
2061 intelligently substitute (e.g., a smaller version of the ‘<code
2062 class=property>caption</code>’ font might be used for the ‘<code
2063 class=property>small-caption</code>’ font), or substitute a user agent
2064 default font. As for regular fonts, if, for a system font, any of the
2065 individual properties are not part of the operating system's available
2066 user preferences, those properties should be set to their initial values.
2068 <p>That is why this property is "almost" a shorthand property: system fonts
2069 can only be specified with this property, not with <a
2070 href="#propdef-font-family" title="font-family!!property">‘<code
2071 class=property>font-family</code>’</a> itself, so <span
2072 class=property>‘<a href="#propdef-font"><code
2073 class=property>font</code></a>’</span> allows authors to do more than
2074 the sum of its subproperties. However, the individual properties such as
2075 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2076 class=property>font-weight</code>’</a> are still given values taken from
2077 the system font, which can be independently varied.
2079 <p>Note that the keywords used for the system fonts listed above are only
2080 treated as keywords when they occur in the initial position, in other
2081 positions the same string is treated as part of the font family name:
2083 <pre> font: menu; /* use the font settings for system menus */
2084 font: large menu; /* use a font family named "menu" */</pre>
2086 <div class=example>
2087 <p style="display:none">Example(s):</p>
2089 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2090 button p { font: menu }
2091 button p em { font-weight: bolder }
2092 </pre>
2094 <p>If the font used for dropdown menus on a particular system happened to
2095 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2096 that were descendants of BUTTON would be displayed as if this rule were
2097 in effect:
2099 <pre>button p { font: 600 9pt Charcoal }
2100 </pre>
2102 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2103 class=property>font</code></a>’</span> shorthand resets to its initial
2104 value any property not explicitly given a value, this has the same effect
2105 as this declaration:
2107 <pre>button p {
2108 font-style: normal;
2109 font-variant: normal;
2110 font-weight: 600;
2111 font-size: 9pt;
2112 line-height: normal;
2113 font-family: Charcoal
2114 }
2115 </pre>
2116 </div>
2117 <!-- prop: font-synthesis -->
2119 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2120 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2121 property</h3>
2123 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2124 <tbody>
2125 <tr>
2126 <td>Name:
2128 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2130 <tr>
2131 <td>Value:
2133 <td>none | [ weight || style ]
2135 <tr>
2136 <td>Initial:
2138 <td>weight style
2140 <tr>
2141 <td>Applies to:
2143 <td>all elements
2145 <tr>
2146 <td>Inherited:
2148 <td>yes
2150 <tr>
2151 <td>Percentages:
2153 <td>N/A
2155 <tr>
2156 <td>Media:
2158 <td>visual
2160 <tr>
2161 <td>Computed value:
2163 <td>as specified
2165 <tr>
2166 <td>Animatable:
2168 <td>no
2169 </table>
2171 <p>This property controls whether user agents are allowed to synthesize
2172 bold or oblique font faces when a font family lacks bold or italic faces.
2173 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2174 specified, user agents must not synthesize bold faces and if ‘<code
2175 class=property>style</code>’ is not specified user agents must not
2176 synthesize italic faces. A value of ‘<code class=property>none</code>’
2177 disallows all synthetic faces.
2179 <div class=example>
2180 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2182 <pre>*:lang(ar) { font-synthesis: none; }
2183 </pre>
2184 </div>
2186 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2188 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2189 id=at-font-face-rule style="font-weight: inherit; font-style:
2190 inherit"><code>@font-face</code></dfn> rule</h3>
2192 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2193 for linking to fonts that are automatically fetched and activated when
2194 needed. This allows authors to select a font that closely matches the
2195 design goals for a given page rather than limiting the font choice to a
2196 set of fonts available on a given platform. A set of font descriptors
2197 define the location of a font resource, either locally or externally,
2198 along with the style characteristics of an individual face. Multiple <a
2199 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2200 construct font families with a variety of faces. Using CSS font matching
2201 rules, a user agent can selectively download only those faces that are
2202 needed for a given piece of text.
2204 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2205 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2206 at-keyword followed by a block of descriptor declarations. In terms of the
2207 grammar, this specification defines the following productions:
2209 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2210 : <a href="#fontfacesym"><i>FONT_FACE_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? [ ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
2211 ;
2213 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2214 : <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>property</i></a> ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>expr</i></a>
2215 ;</pre>
2217 <p>The following new definitions are introduced:
2219 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2220 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2222 <p>The following new token is introduced:
2224 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2226 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2227 specifies a value for every font descriptor, either implicitly or
2228 explicitly. Those not given explicit values in the rule take the initial
2229 value listed with each descriptor in this specification. These descriptors
2230 apply solely within the context of the <a
2231 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2232 are defined, and do not apply to document language elements. There is no
2233 notion of which elements the descriptors apply to or whether the values
2234 are inherited by child elements. When a given descriptor occurs multiple
2235 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2236 rule, only the last descriptor declaration is used and all prior
2237 declarations for that descriptor are ignored.
2239 <div class=example>
2240 <p>To use a downloadable font called Gentium:</p>
2242 <pre>
2243 @font-face {
2244 font-family: Gentium;
2245 src: url(http://example.com/fonts/Gentium.woff);
2246 }
2248 p { font-family: Gentium, serif; }
2249 </pre>
2251 <p>The user agent will download Gentium and use it when rendering text
2252 within paragraph elements. If for some reason the site serving the font
2253 is unavailable, the default serif font will be used.</p>
2254 </div>
2256 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2257 rules define a set of fonts available for use within the documents that
2258 contain these rules. When font matching is done, fonts defined using these
2259 rules are considered before other available fonts on a system.
2261 <p>Downloaded fonts are only available to documents that reference them.
2262 The process of activating these fonts must not make them available to
2263 other applications or to documents that don't directly link to the same
2264 font. User agent implementers might consider it convenient to use
2265 downloaded fonts when rendering characters in other documents for which no
2266 other available font exists as part of the <a
2267 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2268 However, this would cause a security leak since the contents of one page
2269 would be able to affect other pages, something an attacker could use as an
2270 attack vector. These restrictions do not affect caching behavior, fonts
2271 are cached the same way other web resources are cached.
2273 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2274 properties in a declaration block, declarations of any descriptors that
2275 are not supported by the user agent must be ignored. <a
2276 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2277 font-family and src descriptor; if either of these are missing, the <a
2278 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2279 must be ignored entirely.
2281 <p>In cases where user agents have limited platform resources or implement
2282 the ability to disable downloadable font resources, <a
2283 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2284 ignored; the behavior of individual descriptors as defined in this
2285 specification should not be altered.
2287 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2288 href="#descdef-font-family">font-family</a> descriptor</h3>
2290 <table class=descdef>
2291 <tbody>
2292 <tr>
2293 <td>Name:
2295 <td><dfn id=descdef-font-family
2296 title="font-family!!descriptor">font-family</dfn>
2298 <tr>
2299 <td>Value:
2301 <td><a href="#family-name-value"><var><family-name></var></a>
2303 <tr>
2304 <td><em>Initial:</em>
2306 <td>N/A
2307 </table>
2309 <p>This descriptor defines the font family name that will be used in all
2310 CSS font family name matching. It is required for the <a
2311 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2312 overrides the font family names contained in the underlying font data. If
2313 the font family name is the same as a font family available in a given
2314 user's environment, it effectively hides the underlying font for documents
2315 that use the stylesheet. This permits a web author to freely choose
2316 font-family names without worrying about conflicts with font family names
2317 present in a given user's environment. Likewise, platform substitutions
2318 for a given font family name must not be used.
2320 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2321 href="#descdef-src">src</a> descriptor</h3>
2323 <table class=descdef>
2324 <tbody>
2325 <tr>
2326 <td>Name:
2328 <td><dfn id=descdef-src>src</dfn>
2330 <tr>
2331 <td>Value:
2333 <td>[ <url> [format(<string> #)]? | <a
2334 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2336 <tr>
2337 <td><em>Initial:</em>
2339 <td>N/A
2340 </table>
2342 <p>This descriptor specifies the resource containing font data. It is
2343 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2344 rule to be valid. Its value is a prioritized, comma-separated list of
2345 external references or locally-installed font face names. When a font is
2346 needed the user agent iterates over the set of references listed, using
2347 the first one it can successfully activate. Fonts containing invalid data
2348 or local font faces that are not found are ignored and the user agent
2349 loads the next font in the list.
2351 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2352 resolved relative to the location of the style sheet containing the <a
2353 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2354 SVG fonts, the URL points to an element within a document containing SVG
2355 font definitions. If the element reference is omitted, a reference to the
2356 first defined font is implied. Similarly, font container formats that can
2357 contain more than one font must load one and only one of the fonts for a
2358 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2359 Fragment identifiers are used to indicate which font to load. If a
2360 container format lacks a defined fragment identifier scheme,
2361 implementations should use a simple 1-based indexing scheme (e.g.
2362 "font-collection#1" for the first font, "font-collection#2" for the second
2363 font).
2365 <pre>
2366 src: url(fonts/simple.woff); /* load simple.woff relative to stylesheet location */
2367 src: url(/fonts/simple.woff); /* load simple.woff from absolute location */
2368 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2369 </pre>
2371 <p>External references consist of a URL, followed by an optional hint
2372 describing the format of the font resource referenced by that URL. The
2373 format hint contains a comma-separated list of format strings that denote
2374 well-known font formats. Conformant user agents must skip downloading a
2375 font resource if the format hints indicate only unsupported or unknown
2376 font formats. If no format hints are supplied, the user agent should
2377 download the font resource.
2379 <pre>
2380 /* load WOFF font if possible, otherwise use OpenType font */
2381 @font-face {
2382 font-family: bodytext;
2383 src: url(ideal-sans-serif.woff) format("woff"),
2384 url(basic-sans-serif.ttf) format("opentype");
2385 }
2386 </pre>
2388 <p>Format strings defined by this specification:
2390 <table class=data id=fontformats>
2391 <thead>
2392 <tr>
2393 <th>String
2395 <th>Font Format
2397 <th>Common extensions
2399 <tbody>
2400 <tr>
2401 <th>"woff"
2403 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2405 <td>.woff
2407 <tr>
2408 <th>"truetype"
2410 <td><a
2411 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2413 <td>.ttf
2415 <tr>
2416 <th>"opentype"
2418 <td><a
2419 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2421 <td>.ttf, .otf
2423 <tr>
2424 <th>"embedded-opentype"
2426 <td><a
2427 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2428 OpenType</a>
2430 <td>.eot
2432 <tr>
2433 <th>"svg"
2435 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2437 <td>.svg, .svgz
2438 </table>
2440 <p>Given the overlap in common usage between TrueType and OpenType, the
2441 format hints "truetype" and "opentype" must be considered as synonymous; a
2442 format hint of "opentype" does not imply that the font contains Postscript
2443 CFF style glyph data or that it contains OpenType layout information (see
2444 <a href="#platform-props-to-css">Appendix A</a> for more background on
2445 this).
2447 <p>When authors would prefer to use a locally available copy of a given
2448 font and download it if it's not, <code>local()</code> can be used. The
2449 locally-installed <dfn
2450 id=font-face-name-value><var><font-face-name></var></dfn> argument
2451 to <code>local()</code> is a format-specific string that uniquely
2452 identifies a single font face within a larger family. The syntax for a <a
2453 href="#font-face-name-value"><var><font-face-name></var></a> is a
2454 unique font face name enclosed by "local(" and ")". The name can
2455 optionally be enclosed in quotes. If unquoted, the unquoted font family
2456 name processing conventions apply; the name must be a sequence of
2457 identifiers separated by whitespace which is converted to a string by
2458 joining the identifiers together separated by a single space.
2460 <pre>
2461 /* regular face of Gentium */
2462 @font-face {
2463 font-family: MyGentium;
2464 src: local(Gentium), /* use locally available Gentium */
2465 url(Gentium.woff); /* otherwise, download it */
2466 }
2467 </pre>
2469 <p>For OpenType and TrueType fonts, this string is used to match only the
2470 Postscript name or the full font name in the name table of locally
2471 available fonts. Which type of name is used varies by platform and font,
2472 so authors should include both of these names to assure proper matching
2473 across platforms. Platform substitutions for a given font name must not be
2474 used.
2476 <pre>
2477 /* bold face of Gentium */
2478 @font-face {
2479 font-family: MyGentium;
2480 src: local(Gentium Bold), /* full font name */
2481 local(Gentium-Bold), /* Postscript name */
2482 url(GentiumBold.woff); /* otherwise, download it */
2483 font-weight: bold;
2484 }
2485 </pre>
2487 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2488 specifies the characteristics of a single font within a family, the unique
2489 name used with <code>local()</code> specifies a single font, not an entire
2490 font family. Defined in terms of OpenType font data, the Postscript name
2491 is found in the font's <a
2492 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2493 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2494 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2495 Postscript name is the commonly used key for all fonts on OSX and for
2496 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2497 used as a unique key for fonts with TrueType glyphs on Windows.
2499 <p>For OpenType fonts with multiple localizations of the full font name,
2500 the US English version is used (language ID = 0x409 for Windows and
2501 language ID = 0 for Macintosh) or the first localization when a US English
2502 full font name is not available (the OpenType specification recommends
2503 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2504 fonts minimally include US English names</a>). User agents that also match
2505 other full font names, e.g. matching the Dutch name when the current
2506 system locale is set to Dutch, are considered non-conformant. This is done
2507 not to prefer English but to avoid matching inconsistencies across font
2508 versions and OS localizations, since font style names (e.g. "Bold") are
2509 frequently localized into many languages and the set of localizations
2510 available varies widely across platform and font version. User agents that
2511 match a concatenation of family name (nameID = 1) with style name (nameID
2512 = 2) are considered non-conformant.
2514 <p>This also allows for referencing faces that belong to larger families
2515 that cannot otherwise be referenced.
2517 <div class=example>
2518 <p>Use a local font or reference an SVG font in another document:</p>
2520 <pre>
2521 @font-face {
2522 font-family: Headline;
2523 src: local(Futura-Medium),
2524 url(fonts.svg#MyGeometricModern) format("svg");
2525 }
2526 </pre>
2528 <p>Create an alias for local Japanese fonts on different platforms:</p>
2530 <pre>
2531 @font-face {
2532 font-family: jpgothic;
2533 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2534 }
2535 </pre>
2537 <p>Reference a font face that cannot be matched within a larger family:</p>
2539 <pre>
2540 @font-face {
2541 font-family: Hoefler Text Ornaments;
2542 /* has the same font properties as Hoefler Text Regular */
2543 src: local(HoeflerText-Ornaments);
2544 }
2545 </pre>
2547 <p>Since localized fullnames never match, a document with the header style
2548 rules below would always render using the default serif font, regardless
2549 whether a particular system locale parameter is set to Finnish or not:</p>
2551 <pre>
2552 @font-face {
2553 font-family: SectionHeader;
2554 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2555 font-weight: bold;
2556 }
2558 h2 { font-family: SectionHeader, serif; }
2559 </pre>
2561 <p>A conformant user agent would never load the font ‘<code
2562 class=css>gentium.eot</code>’ in the example below, since it is
2563 included in the first definition of the ‘<a href="#descdef-src"><code
2564 class=property>src</code></a>’ descriptor which is overridden by the
2565 second definition in the same <a
2566 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2568 <pre>
2569 @font-face {
2570 font-family: MainText;
2571 src: url(gentium.eot); /* for use with older user agents */
2572 src: local("Gentium"), url(gentium.woff); /* Overrides src definition */
2573 }
2574 </pre>
2575 </div>
2577 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2578 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2579 href="#descdef-font-weight">font-weight</a>, <a
2580 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2582 <table class=descdef>
2583 <tbody>
2584 <tr>
2585 <td>Name:
2587 <td><dfn id=descdef-font-style
2588 title="font-style!!descriptor">font-style</dfn>
2590 <tr>
2591 <td>Value:
2593 <td>normal | italic | oblique
2595 <tr>
2596 <td><em>Initial:</em>
2598 <td>normal
2599 </table>
2601 <table class=descdef>
2602 <tbody>
2603 <tr>
2604 <td>Name:
2606 <td><dfn id=descdef-font-weight
2607 title="font-weight!!descriptor">font-weight</dfn>
2609 <tr>
2610 <td>Value:
2612 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2614 <tr>
2615 <td><em>Initial:</em>
2617 <td>normal
2618 </table>
2620 <table class=descdef>
2621 <tbody>
2622 <tr>
2623 <td>Name:
2625 <td><dfn id=descdef-font-stretch
2626 title="font-stretch!!descriptor">font-stretch</dfn>
2628 <tr>
2629 <td>Value:
2631 <td>normal | ultra-condensed | extra-condensed | condensed |
2632 semi-condensed | semi-expanded | expanded | extra-expanded |
2633 ultra-expanded
2635 <tr>
2636 <td><em>Initial:</em>
2638 <td>normal
2639 </table>
2641 <p>These descriptors define the characteristics of a font face and are used
2642 in the process of matching styles to specific faces. For a font family
2643 defined with several <a
2644 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2645 can either download all faces in the family or use these descriptors to
2646 selectively download font faces that match actual styles used in document.
2647 The values for these descriptors are the same as those for the
2648 corresponding font properties except that relative keywords are not
2649 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2650 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2651 these descriptors are omitted, initial values are assumed.
2653 <p>The value for these font face style attributes is used in place of the
2654 style implied by the underlying font data. This allows authors to combine
2655 faces in flexible combinations, even in situations where the original font
2656 data was arranged differently. User agents that implement synthetic
2657 bolding and obliquing must only apply synthetic styling in cases where the
2658 font descriptors imply this is needed, rather than based on the style
2659 attributes implied by the font data.
2661 <div class=example>
2662 <p>The font descriptors defined in this section are used for selecting a
2663 font from within the set of fonts defined by <a
2664 href="#at-font-face-rule"><code>@font-face</code></a> rules for a given
2665 family.</p>
2667 <p>Consider a family containing a single, regular face:</p>
2669 <pre>
2670 @font-face {
2671 font-family: BaskervilleSimple;
2672 src: url(baskerville-regular.woff);
2673 }
2674 </pre>
2676 <p>Unstyled text would display using the regular face defined in the <a
2677 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2679 <div class=figure><img alt="regular face display"
2680 src=fiddlesticks-regular.png width=373></div>
2682 <p>However, italic text would display in most user agents using
2683 synthetically obliqued glyphs from the regular face, since a separate
2684 italic face is not defined:</p>
2686 <div class=figure><img alt="synthetic italics display"
2687 src=fiddlesticks-synitalics.png width=373></div>
2689 <p>Now consider a family for which an actual italic face is defined:</p>
2691 <pre>
2692 @font-face {
2693 font-family: BaskervilleFull;
2694 src: url(baskerville-regular.woff);
2695 }
2697 @font-face {
2698 font-family: BaskervilleFull;
2699 src: url(baskerville-italic.woff);
2700 font-style: italic;
2701 }
2702 </pre>
2704 <p>The second <a href="#at-font-face-rule"><code>@font-face</code></a>
2705 rule defines the font resource <code>baskerville-italic.woff</code> to
2706 have style attributes of normal weight, normal stretch and italic style.
2707 When displaying italic text, the user agent will use this font, since
2708 it's the closest match for italic text. Thus, the text will display using
2709 glyphs designed by a type designer rather than using synthetically
2710 obliqued glyphs from the regular face:</p>
2712 <div class=figure><img alt="real italics display"
2713 src=fiddlesticks-italics.png width=373></div>
2715 <p>See the section on <a href="#font-style-matching">font matching</a> for
2716 more complete details of the process used to select a particular face
2717 within a font family.</p>
2718 </div>
2720 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2721 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2723 <table class=descdef>
2724 <tbody>
2725 <tr>
2726 <td>Name:
2728 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2730 <tr>
2731 <td>Value:
2733 <td><a href="#urange-value"><var><urange></var></a> #
2735 <tr>
2736 <td><em>Initial:</em>
2738 <td>U+0-10FFFF
2739 </table>
2741 <p>This descriptor defines the set of Unicode codepoints that may be
2742 supported by the font face for which it is declared. The descriptor value
2743 is a comma-delimited list of Unicode range (<a
2744 href="#urange-value"><var><urange></var></a>) values. The union of
2745 these ranges defines the set of codepoints that serves as a hint for user
2746 agents when deciding whether or not to download a font resource for a
2747 given text run.
2749 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2750 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2751 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2752 "U+" or "u+" prefix followed by a codepoint range in one of the three
2753 forms listed below. Ranges that do not fit one of the these forms are
2754 invalid and cause the declaration to be ignored.
2756 <dl>
2757 <dt>single codepoint (e.g. U+416)
2759 <dd>a Unicode codepoint, represented as one to six hexadecimal digits
2761 <dt>interval range (e.g. U+400-4ff)
2763 <dd>represented as two hyphen-separated Unicode codepoints indicating the
2764 inclusive start and end codepoints of a range
2766 <dt>wildcard range (e.g. U+4??)
2768 <dd>defined by the set of codepoints implied when trailing ‘<code
2769 class=css>?</code>’ characters signify any hexadeximal digit
2770 </dl>
2772 <p>Individual codepoints are written using hexadecimal values that
2773 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2774 codepoints</a>. Unicode codepoint values must be between 0 and 10FFFF
2775 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2776 interval ranges, the start and end codepoints must be within the range
2777 noted above and the end codepoint must be greater than or equal to the
2778 start codepoint.
2780 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2781 "U+???") are valid and equivalent to a wildcard range with an initial zero
2782 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2783 the range of Unicode codepoints are invalid. Because of this, the maximum
2784 number of trailing ‘<code class=css>?</code>’ wildcard characters is
2785 five, even though the <a
2786 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2787 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2789 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2790 href="#descdef-unicode-range"><code
2791 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2792 may overlap. The union of these ranges defines the set of codepoints for
2793 which the corresponding font may be used. User agents must not download or
2794 use the font for codepoints outside this set. User agents may normalize
2795 the list of ranges into a list that is different but represents the same
2796 set of codepoints.
2798 <p>The associated font might not contain glyphs for the entire set of
2799 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2800 class=property>unicode-range</code></a>’ descriptor. When the font is
2801 used, the <dfn id=effective-character-map>effective character map</dfn> is
2802 the intersection of the codepoints defined by ‘<a
2803 href="#descdef-unicode-range"><code
2804 class=property>unicode-range</code></a>’ with the font's <a
2805 href="#character-map"><em>character map</em></a>. This allows authors to
2806 define supported ranges in terms of broad ranges without worrying about
2807 the precise codepoint ranges supported by the underlying font.
2809 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2810 to define composite fonts</h3>
2812 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2813 with different unicode ranges for the same family and style descriptor
2814 values can be used to create composite fonts that mix the glyphs from
2815 different fonts for different scripts. This can be used to combine fonts
2816 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2817 or it can be used by authors as a way of segmenting a font into fonts for
2818 commonly used characters and less frequently used characters. Since the
2819 user agent will only pull down the fonts it needs this helps reduce page
2820 bandwidth.
2822 <p>If the unicode ranges overlap for a set of <a
2823 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2824 family and style descriptor values, the rules are ordered in the reverse
2825 order they were defined; the last rule defined is the first to be checked
2826 for a given character.
2828 <p>Example ranges for specific languages or characters:
2830 <dl>
2831 <dt>unicode-range: U+A5;
2833 <dd>a single code point, the yen/yuan symbol
2835 <dt>unicode-range: U+0-7F;
2837 <dd>code range for basic ASCII characters
2839 <dt>unicode-range: U+590-5ff;
2841 <dd>code range for Hebrew characters
2843 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2845 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2846 yen/yuan symbol
2847 </dl>
2849 <div class=example>
2850 <p>The BBC provides news services in a wide variety of languages, many
2851 that are not well supported across all platforms. Using an <a
2852 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2853 provide a font for any of these languages, as it already does via a
2854 manual font download.</p>
2856 <pre>
2857 @font-face {
2858 font-family: BBCBengali;
2859 src: url(fonts/BBCBengali.woff) format("woff");
2860 unicode-range: U+00-FF, U+980-9FF;
2861 }
2862 </pre>
2863 </div>
2865 <div class=example>
2866 <p>Technical documents often require a wide range of symbols. The STIX
2867 Fonts project is one project aimed at providing fonts to support a wide
2868 range of technical typesetting in a standardized way. The example below
2869 shows the use of a font that provides glyphs for many of the mathematical
2870 and technical symbol ranges within Unicode:</p>
2872 <pre>
2873 @font-face {
2874 font-family: STIXGeneral;
2875 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2876 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2877 }
2878 </pre>
2879 </div>
2881 <div class=example>
2882 <p>This example shows how an author can override the glyphs used for Latin
2883 characters in a Japanese font with glyphs from a different font. The
2884 first rule specifies no range so it defaults to the entire range. The
2885 range specified in the second rule overlaps but takes precedence because
2886 it is defined later.</p>
2888 <pre>
2889 @font-face {
2890 font-family: JapaneseWithGentium;
2891 src: local(MSMincho);
2892 /* no range specified, defaults to entire range */
2893 }
2895 @font-face {
2896 font-family: JapaneseWithGentium;
2897 src: url(../fonts/Gentium.woff);
2898 unicode-range: U+0-2FF;
2899 }
2900 </pre>
2901 </div>
2903 <div class=example>
2904 <p>Consider a family constructed to optimize bandwidth by separating out
2905 Latin, Japanese and other characters into different font files:</p>
2907 <pre>
2908 /* fallback font - size: 4.5MB */
2909 @font-face {
2910 font-family: DroidSans;
2911 src: url(DroidSansFallback.woff);
2912 /* no range specified, defaults to entire range */
2913 }
2915 /* Japanese glyphs - size: 1.2MB */
2916 @font-face {
2917 font-family: DroidSans;
2918 src: url(DroidSansJapanese.woff);
2919 unicode-range: U+3000-9FFF, U+ff??;
2920 }
2922 /* Latin, Greek, Cyrillic along with some
2923 punctuation and symbols - size: 190KB */
2924 @font-face {
2925 font-family: DroidSans;
2926 src: url(DroidSans.woff);
2927 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2928 }
2929 </pre>
2931 <p>For simple Latin text, only the font for Latin characters is
2932 downloaded:</p>
2934 <pre>
2935 body { font-family: DroidSans; }
2937 <p>This is that</p>
2938 </pre>
2940 <p>In this case the user agent first checks the unicode-range for the font
2941 containing Latin characters (DroidSans.woff). Since all the characters
2942 above are in the range U+0-5FF, the user agent downloads the font and
2943 renders the text with that font.</p>
2945 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2947 <pre>
2948 <p>This &#x21e8; that<p>
2949 </pre>
2951 <p>The user agent again first checks the unicode-range of the font
2952 containing Latin characters. Since U+2000-2300 includes the arrow code
2953 point (U+21E8), the user agent downloads the font. For this character
2954 however the Latin font does not have a matching glyph, so the effective
2955 unicode-range used for font matching excludes this code point. Next, the
2956 user agent evaluates the Japanese font. The unicode-range for the
2957 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2958 user agent does not download the Japanese font. Next the fallback font is
2959 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2960 rule for the fallback font does not define unicode-range so its value
2961 defaults to the range of all Unicode code points. The fallback font is
2962 downloaded and used to render the arrow character.</p>
2963 </div>
2965 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2966 href="#descdef-font-variant">font-variant</a> and <a
2967 href="#descdef-font-feature-settings">font-feature-settings</a>
2968 descriptors</h3>
2970 <table class=descdef>
2971 <tbody>
2972 <tr>
2973 <td>Name:
2975 <td><dfn id=descdef-font-variant
2976 title="font-variant!!descriptor">font-variant</dfn>
2978 <tr>
2979 <td>Value:
2981 <td><a href="#font-variant-normal-value"
2982 title="normal!!font-variant">normal</a> | <a
2983 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2984 <a href="#common-lig-values"><var><common-lig-values></var></a>
2985 || <a
2986 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2987 || <a
2988 href="#historical-lig-values"><var><historical-lig-values></var></a>
2989 || <a
2990 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2991 || <a href="#stylistic"><var
2992 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2993 href="#historical-forms"><var>historical-forms</var></a> || <a
2994 href="#styleset"><var
2995 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2996 href="#character-variant"><var
2997 title=character-variant>character-variant(<feature-value-name>
2998 #)</var></a> || <a href="#swash"><var
2999 title=swash>swash(<feature-value-name>)</var></a> || <a
3000 href="#ornaments"><var
3001 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
3002 href="#annotation"><var
3003 title=annotation>annotation(<feature-value-name>)</var></a> || [
3004 <a href="#small-caps"><i>small-caps</i></a> | <a
3005 href="#all-small-caps"><i>all-small-caps</i></a> | <a
3006 href="#petite-caps"><i>petite-caps</i></a> | <a
3007 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
3008 href="#unicase"><i>unicase</i></a> | <a
3009 href="#titling-caps"><i>titling-caps</i></a> ] || <a
3010 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
3011 || <a
3012 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
3013 || <a
3014 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
3015 || <a href="#ordinal"><i>ordinal</i></a> || <a
3016 href="#slashed-zero"><i>slashed-zero</i></a> || <a
3017 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
3018 || <a
3019 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
3020 || <a href="#ruby"><i>ruby</i></a> ]
3022 <tr>
3023 <td><em>Initial:</em>
3025 <td>normal
3026 </table>
3028 <table class=descdef>
3029 <tbody>
3030 <tr>
3031 <td>Name:
3033 <td><dfn id=descdef-font-feature-settings
3034 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
3036 <tr>
3037 <td>Value:
3039 <td><a href="#font-feature-settings-normal-value"
3040 title="normal!!font-feature-settings">normal</a> | <a
3041 href="#feature-tag-value"><var><feature-tag-value></var></a> #
3043 <tr>
3044 <td><em>Initial:</em>
3046 <td>normal
3047 </table>
3049 <p>These descriptors define initial settings that apply when the font
3050 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
3051 rule is rendered. They do not affect font selection. Values are identical
3052 to those defined for the corresponding <a href="#propdef-font-variant"
3053 title="font-variant!!property">‘<code
3054 class=property>font-variant</code>’</a> and <a
3055 href="#propdef-font-feature-settings"
3056 title="font-feature-settings!!property">‘<code
3057 class=property>font-feature-settings</code>’</a> properties defined
3058 below except that the value ‘<code class=property>inherit</code>’ is
3059 omitted. When multiple font feature descriptors or properties are used,
3060 the cumulative effect on text rendering is detailed in the section <a
3061 href="#font-feature-resolution">Font Feature Resolution</a> below. In
3062 cases where specific values define synthesized fallback for certain <a
3063 href="#propdef-font-variant" title="font-variant!!property">‘<code
3064 class=property>font-variant</code>’</a> subproperties, the same
3065 synthesized fallback applies when used within those values are used with
3066 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
3067 class=property>font-variant</code>’</a> descriptor.
3069 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
3070 guidelines</h3>
3072 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
3073 designed to allow lazy loading of font resources that are only downloaded
3074 when used within a document. A stylesheet can include <a
3075 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
3076 of fonts of which only a select set are used; user agents must only
3077 download those fonts that are referred to within the style rules
3078 applicable to a given page. User agents that download all fonts defined in
3079 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
3080 considering whether those fonts are in fact used within a page are
3081 considered non-conformant. In cases where a font might be downloaded in
3082 character fallback cases, user agents may download a font if it's
3083 contained within the computed value of <a href="#propdef-font-family"
3084 title="font-family!!property">‘<code
3085 class=property>font-family</code>’</a> for a given text run.
3087 <pre>
3088 @font-face {
3089 font-family: GeometricModern;
3090 src: url(font.woff);
3091 }
3093 p {
3094 /* font will be downloaded for pages with p elements */
3095 font-family: GeometricModern, sans-serif;
3096 }
3098 h2 {
3099 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
3100 font-family: Futura, GeometricModern, sans-serif;
3101 }
3102 </pre>
3104 <p>In cases where textual content is loaded before downloadable fonts are
3105 available, user agents may render text as it would be rendered if
3106 downloadable font resources are not available or they may render text
3107 transparently with fallback fonts to avoid a flash of text using a
3108 fallback font. In cases where the font download fails user agents must
3109 display text, simply leaving transparent text is considered non-conformant
3110 behavior. Authors are advised to use fallback fonts in their font lists
3111 that closely match the metrics of the downloadable fonts to avoid large
3112 page reflows where possible.
3114 <p><a id=same-origin-restriction> </a><a
3115 id=allowing-cross-origin-font-loading> </a>
3117 <h3 id=font-fetching-requirements><span class=secno>4.9 </span>Font
3118 fetching requirements</h3>
3119 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3120 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3121 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3122 -->
3124 <p>For font loads, user agents must use the <a
3125 href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
3126 CORS-enabled fetch</a> method defined by the <a href="#HTML5"
3127 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification for URL's
3128 defined within @font-face rules. When fetching, user agents must use
3129 "Anonymous" mode, set the referrer source to the stylesheet's URL and set
3130 the origin to the URL of the containing document.
3132 <p class=note>The implications of this for authors are that fonts will
3133 typically not be loaded cross-origin unless authors specifically takes
3134 steps to permit cross-origin loads. Sites can explicitly allow cross-site
3135 loading of font data using the <code>Access-Control-Allow-Origin</code>
3136 HTTP header. For other schemes, no explicit mechanism to allow
3137 cross-origin loading, beyond what is permitted by the <a
3138 href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
3139 CORS-enabled fetch</a> method, is defined or required.
3141 <div class=example> For the examples given below, assume that a document is
3142 located at <code>http://example.com/page.html</code> and all URL's link to
3143 valid font resources supported by the user agent. Fonts defined with the
3144 ‘<a href="#descdef-src"><code class=property>src</code></a>’
3145 descriptor values below will be loaded:
3146 <pre>/* same origin (i.e. domain, scheme, port match document) */
3147 src: url(fonts/simple.woff);
3149 /* data url's with no redirects are treated as same origin */
3150 src: url("data:application/font-woff;base64,...");
3152 /* cross origin, different domain */
3153 /* Access-Control-Allow-Origin response header set to '*' */
3154 src: url(http://another.example.com/fonts/simple.woff);
3155 </pre>
3156 Fonts defined with the ‘<a href="#descdef-src"><code
3157 class=property>src</code></a>’ descriptor values below will fail to
3158 load:
3159 <pre>/* cross origin, different scheme */
3160 /* no Access-Control-xxx headers in response */
3161 src: url(https://example.com/fonts/simple.woff);
3163 /* cross origin, different domain */
3164 /* no Access-Control-xxx headers in response */
3165 src: url(http://another.example.com/fonts/simple.woff);
3166 </pre>
3167 </div>
3169 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3170 Algorithm</h2>
3172 <p>The algorithm below describes how fonts are associated with individual
3173 runs of text. For each character in the run a font family is chosen and a
3174 particular font face is selected containing a glyph for that character.
3176 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3177 font family names</h3>
3179 <p>As part of the font matching algorithm outlined below, user agents must
3180 match font family names used in style rules with actual font family names
3181 contained in fonts available in a given environment or with font family
3182 names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
3183 rules. User agents must match these names case insensitively, using the
3184 "Default Caseless Matching" algorithm outlined in the Unicode
3185 specification <a href="#UNICODE"
3186 rel=biblioentry>[UNICODE]<!--{{!UNICODE}}--></a>. This algorithm is
3187 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3188 the algorithm must be applied without normalizing the strings involved and
3189 without applying any language-specific tailorings. The case folding method
3190 specified by this algorithm uses the case mappings with status field
3191 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3192 in the CaseFolding.txt file of the Unicode Character Database.
3194 <p class=note> For authors this means that font family names are matched
3195 case insensitively, whether those names exist in a platform font or in the
3196 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3197 in a stylesheet. Authors should take care to ensure that names use a
3198 character sequence consistent with the actual font family name,
3199 particularly when using combining characters such as diacritical marks.
3200 For example, a family name that contains an uppercase A (U+0041) followed
3201 by a combining ring (U+030A) will <strong>not</strong> match a name that
3202 looks identical but which uses the precomposed lowercase a-ring character
3203 (U+00E5) instead of the combining sequence.
3205 <p class=note> Implementors should take care to verify that a given
3206 caseless string comparison implementation uses this precise algorithm and
3207 not assume that a given platform string matching routine follows it, as
3208 many of these have locale-specific behavior or use some level of string
3209 normalization.
3211 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3212 styles</h3>
3214 <p>The procedure for choosing a font for a given character in a run of text
3215 consists of iterating over the font families named by the <a
3216 href="#propdef-font-family" title="font-family!!property">‘<code
3217 class=property>font-family</code>’</a> property, selecting a font face
3218 with the appropriate style based on other font properties and then
3219 determining whether a glyph exists for the given character. This is done
3220 using the <dfn id=character-map>character map</dfn> of the font, data
3221 which maps characters to the default glyph for that character. A font is
3222 considered to <dfn id=support>support</dfn> a given character if (1) the
3223 character is contained in the font's <a
3224 href="#character-map"><em>character map</em></a> and (2) if required by
3225 the containing script, shaping information is available for that
3226 character.
3228 <p>Some legacy fonts may include a given character in the <a
3229 href="#character-map"><em>character map</em></a> but lack the shaping
3230 information (e.g. <a
3231 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3232 layout tables</a> or <a
3233 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3234 tables</a>) necessary for correctly rendering text runs containing that
3235 character.
3237 <p>Codepoint sequences consisting of a base character followed by a
3238 sequence of combining characters are treated slightly differently, see the
3239 section on <a href="#cluster-matching">cluster matching</a> below.
3241 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3242 given font family is defined to be the face that would be selected if all
3243 font style properties were set to their initial value.
3245 <ol id=fontmatchingalg>
3246 <li>Using the computed font property values for a given element, the user
3247 agent starts with the first family name specified by the <a
3248 href="#propdef-font-family" title="font-family!!property">‘<code
3249 class=property>font-family</code>’</a> property.
3251 <li>If the family name is a generic family keyword, the user agent looks
3252 up the appropriate font family name to be used. User agents may choose
3253 the generic font family to use based on the language of the containing
3254 element or the Unicode range of the character.
3256 <li>For other family names, the user agent attempts to find the family
3257 name among fonts defined via <a
3258 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3259 among available system fonts, matching names with a <a
3260 href="#font-family-casing">case-insensitive comparison</a> as outlined in
3261 the section above. On systems containing fonts with multiple localized
3262 font family names, user agents must match any of these names independent
3263 of the underlying system locale or platform API used. If the font
3264 resources defined for a given face in an <a
3265 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3266 available or contain invalid font data, then the face should be treated
3267 as not present in the family. If no faces are present for a family
3268 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3269 rules, the family should be treated as missing; matching a platform font
3270 with the same name must not occur in this case.
3272 <li>If a font family match occurs, the user agent assembles the set of
3273 font faces in that family and then narrows the set to a single face using
3274 other font properties in the order given below. A group of faces defined
3275 via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
3276 identical font descriptor values but differing ‘<a
3277 href="#descdef-unicode-range"><code
3278 class=property>unicode-range</code></a>’ values are considered to be a
3279 single <dfn id=composite-face>composite face</dfn> for this step:
3280 <ol id=fontstylematchingalg>
3281 <li><a href="#propdef-font-stretch"
3282 title="font-stretch!!property">‘<code
3283 class=property>font-stretch</code>’</a> is tried first. If the
3284 matching set contains faces with width values matching the <a
3285 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3286 class=property>font-stretch</code>’</a> value, faces with other width
3287 values are removed from the matching set. If there is no face that
3288 exactly matches the width value the nearest width is used instead. If
3289 the value of <a href="#propdef-font-stretch"
3290 title="font-stretch!!property">‘<code
3291 class=property>font-stretch</code>’</a> is <a
3292 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3293 class=property>normal</code>’</a> or one of the condensed values,
3294 narrower width values are checked first, then wider values. If the
3295 value of <a href="#propdef-font-stretch"
3296 title="font-stretch!!property">‘<code
3297 class=property>font-stretch</code>’</a> is one of the expanded
3298 values, wider values are checked first, followed by narrower values.
3299 Once the closest matching width has been determined by this process,
3300 faces with other widths are removed from the matching set.
3302 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3303 class=property>font-style</code>’</a> is tried next. If the value of
3304 <a href="#propdef-font-style" title="font-style!!property">‘<code
3305 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3306 class=property>italic</code></a>’, italic faces are checked first,
3307 then oblique, then normal faces. If the value is ‘<a
3308 href="#oblique"><code class=property>oblique</code></a>’, oblique
3309 faces are checked first, then italic faces and then normal faces. If
3310 the value is <a href="#font-style-normal-value"
3311 title="normal!!font-style">‘<code
3312 class=property>normal</code>’</a>, normal faces are checked first,
3313 then oblique faces, then italic faces. Faces with other style values
3314 are excluded from the matching set. User agents are permitted to
3315 distinguish between italic and oblique faces within platform font
3316 families but this is not required, so all italic or oblique faces may
3317 be treated as italic faces. However, within font families defined via
3318 <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
3319 and oblique faces must be distinguished using the value of the <a
3320 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3321 class=property>font-style</code>’</a> descriptor. For families that
3322 lack any italic or oblique faces, users agents may create artificial
3323 oblique faces, if this is permitted by the value of the ‘<a
3324 href="#propdef-font-synthesis"><code
3325 class=property>font-synthesis</code></a>’ property.
3327 <li><a href="#propdef-font-weight"
3328 title="font-weight!!property">‘<code
3329 class=property>font-weight</code>’</a> is matched next, so it will
3330 always reduce the matching set to a single font face. If bolder/lighter
3331 relative weights are used, the effective weight is calculated based on
3332 the inherited weight value, as described in the definition of the <a
3333 href="#propdef-font-weight" title="font-weight!!property">‘<code
3334 class=property>font-weight</code>’</a> property. Given the desired
3335 weight and the weights of faces in the matching set after the steps
3336 above, if the desired weight is available that face matches. Otherwise,
3337 a weight is chosen using the rules below:
3338 <ul>
3339 <li>If the desired weight is less than 400, weights below the desired
3340 weight are checked in descending order followed by weights above the
3341 desired weight in ascending order until a match is found.
3343 <li>If the desired weight is greater than 500, weights above the
3344 desired weight are checked in ascending order followed by weights
3345 below the desired weight in descending order until a match is found.
3347 <li>If the desired weight is 400, 500 is checked first and then the
3348 rule for desired weights less than 400 is used.
3350 <li>If the desired weight is 500, 400 is checked first and then the
3351 rule for desired weights less than 400 is used.
3352 </ul>
3354 <li><span class=property>‘<a href="#propdef-font-size"><code
3355 class=property>font-size</code></a>’</span> must be matched within a
3356 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3357 are rounded to the nearest whole pixel, while the tolerance for
3358 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3359 by ‘<code class=property>em</code>’ values in other properties, are
3360 based on the <span class=property>‘<a href="#propdef-font-size"><code
3361 class=property>font-size</code></a>’</span> value that is used, not
3362 the one that is specified.
3363 </ol>
3365 <li>
3366 <p>If the matched face is defined via <a
3367 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
3368 must use the procedure below to select a single font:
3370 <ol>
3371 <li>If the font resource has not been loaded and the range of characters
3372 defined by the ‘<a href="#descdef-unicode-range"><code
3373 class=property>unicode-range</code></a>’ descriptor value includes
3374 the character in question, load the font.
3376 <li>After downloading, if the <a
3377 href="#effective-character-map"><em>effective character map</em></a>
3378 supports the character in question, select that font.
3379 </ol>
3381 <p>When the matched face is a <a href="#composite-face"><em>composite
3382 face</em></a>, user agents must use the procedure above on each of the
3383 faces in the <a href="#composite-face"><em>composite face</em></a> in
3384 reverse order of <a
3385 href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
3387 <p>While the download occurs, user agents may either wait until the font
3388 is downloaded or render once with substituted font metrics and render
3389 again once the font is downloaded.</p>
3391 <li>
3392 <p>If no matching face exists or the matched face does not contain a
3393 glyph for the character to be rendered, the next family name is selected
3394 and the previous three steps repeated. Glyphs from other faces in the
3395 family are not considered. The only exception is that user agents may
3396 optionally substitute a synthetically obliqued version of the <a
3397 href="#default-face"><em>default face</em></a> if that face supports a
3398 given glyph and synthesis of these faces is permitted by the value of
3399 the ‘<a href="#propdef-font-synthesis"><code
3400 class=property>font-synthesis</code></a>’ property. For example, a
3401 synthetic italic version of the regular face may be used if the italic
3402 face doesn't support glyphs for Arabic.</p>
3403 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3406 <li>If there are no more font families to be evaluated and no matching
3407 face has been found, then the user agent performs a <dfn
3408 id=system-font-fallback>system font fallback</dfn> procedure to find the
3409 best match for the character to be rendered. The result of this procedure
3410 may vary across user agents.
3412 <li>If a particular character cannot be displayed using any font, the user
3413 agent should indicate by some means that a character is not being
3414 displayed, displaying either a symbolic representation of the missing
3415 glyph (e.g. using a <a
3416 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3417 Font</a>) or using the missing character glyph from a default font.
3418 </ol>
3420 <p>Optimizations of this process are allowed provided that an
3421 implementation behaves as if the algorithm had been followed exactly.
3422 Matching occurs in a well-defined order to ensure that the results are as
3423 consistent as possible across user agents, given an identical set of
3424 available fonts and rendering technology.
3426 <p>The <dfn id=first-available-font>first available font</dfn>, used in the
3427 definition of <a
3428 href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
3429 lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
3430 class=property>ch</code>’, is defined to be the first available font
3431 that would match any character given font families in the ‘<code
3432 class=property>font-family</code>’ list (or a user agent's default font
3433 if none are available).
3435 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3437 <p>When text contains characters such as combining marks, ideally the base
3438 character should be rendered using the same font as the mark, this assures
3439 proper placement of the mark. For this reason, the font matching algorithm
3440 for clusters is more specialized than the general case of matching a
3441 single character by itself. For sequences containing variation selectors,
3442 which indicate the precise glyph to be used for a given character, user
3443 agents always attempt <a href="#system-font-fallback"><em>system font
3444 fallback</em></a> to find the appropriate glyph before using the default
3445 glyph of the base character.
3447 <p>A sequence of codepoints containing combining mark or other modifiers is
3448 termed a grapheme cluster (see <a href="#CSS3TEXT"
3449 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3450 description). For a given cluster containing a base character, <em>b</em>
3451 and a sequence of combining characters <em>c1, c2…</em>, the entire
3452 cluster is matched using these steps:
3454 <ol>
3455 <li>For each family in the font list, a face is chosen using the style
3456 selection rules defined in the previous section.
3457 <ol>
3458 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3459 completely supported by the font, select this font for the sequence.
3461 <li>If a sequence of multiple codepoints is canonically equivalent to a
3462 single character and the font <a href="#support"><em
3463 title=support>supports</em></a> that character, select this font for
3464 the sequence and use the glyph associated with the canonically
3465 equiavlent character for the entire cluster.
3466 </ol>
3468 <li>If no font was found in the font list in step 1:
3469 <ol>
3470 <li>If <em>c1</em> is a variation selector, system fallback must be used
3471 to find a font that <a href="#support"><em
3472 title=support>supports</em></a> the full sequence of <em>b + c1</em>.
3473 If no font on the system <a href="#support"><em
3474 title=support>supports</em></a> the full sequence, match the single
3475 character <em>b</em> using the normal procedure for matching single
3476 characters and ignore the variation selector. Note: a sequence with
3477 more than one variation selector must be treated as an encoding error
3478 and the trailing selectors must be ignored. <a href="#UNICODE"
3479 rel=biblioentry>[UNICODE]<!--{{!UNICODE}}--></a>
3481 <li>Otherwise, the user agent may optionally use system font fallback to
3482 match a font that <a href="#support"><em
3483 title=support>supports</em></a> the entire cluster.
3484 </ol>
3486 <li>If no font is found in step 2, use the matching sequence from step 1
3487 to determine the longest sequence that is completely <a
3488 href="#support"><em title=support>supported</em></a> by a font in the
3489 font list and attempt to match the remaining combining characters
3490 separately using the rules for single characters.
3491 </ol>
3493 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3494 issues</h3>
3496 <p>CSS font matching is always performed on text runs containing Unicode
3497 characters, so documents using legacy encodings are assumed to have been
3498 transcoded before matching fonts. For fonts containing <a
3499 href="#character-map"><em title="character map">character maps</em></a>
3500 for both legacy encodings and Unicode, the contents of the legacy encoding
3501 <a href="#character-map"><em>character map</em></a> must have no effect on
3502 the results of the font matching process.
3504 <p>The font matching process does not assume that text runs are in either
3505 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3506 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3507 details). Fonts may only support precomposed forms and not the decomposed
3508 sequence of base character plus combining marks. Authors should always
3509 tailor their choice of fonts to their content, including whether that
3510 content contains normalized or denormalized character streams.
3512 <p>If a given character is a Private-Use Area Unicode codepoint, user
3513 agents must only match font families named in the ‘<code
3514 class=property>font-family</code>’ list that are not generic families.
3515 If none of the families named in the ‘<code
3516 class=property>font-family</code>’ list contain a glyph for that
3517 codepoint, user agents must display some form of missing glyph symbol for
3518 that character rather than attempting <a
3519 href="#system-font-fallback"><em>system font fallback</em></a> for that
3520 codepoint. When matching the replacement character U+FFFD, user agents may
3521 skip the font matching process and immediately display some form of
3522 missing glyph symbol, they are not required to display the glyph from the
3523 font that would be selected by the font matching process.
3525 <p>In general, the fonts for a given family will all have the same or
3526 similar <a href="#character-map"><em title="character map">character
3527 maps</em></a>. The process outlined here is designed to handle even font
3528 families containing faces with widely variant <a href="#character-map"><em
3529 title="character map">character maps</em></a>. However, authors are
3530 cautioned that the use of such families can lead to unexpected results.
3532 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3533 changes since CSS 2.1</h3>
3535 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3536 These changes were made to better reflect actual font matching behavior
3537 across user agent implementations.
3539 <p>Differences compared to the font matching algorithm in CSS 2.1:
3541 <ul>
3542 <li>The algorithm includes font-stretch matching.
3544 <li>All possible font-style matching scenarios are delineated.
3546 <li>Small-caps fonts are not matched as part of the font matching process,
3547 they are now handled via font features.
3549 <li>Unicode variation selector matching is required.
3551 <li>Cluster sequences are matched as a unit.
3552 </ul>
3554 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3555 examples</h3>
3557 <div class=example>
3558 <p>It's useful to note that the CSS selector syntax may be used to create
3559 language-sensitive typography. For example, some Chinese and Japanese
3560 characters are unified to have the same Unicode code point, although the
3561 abstract glyphs are not the same in the two languages.
3563 <pre>*:lang(ja) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3564 *:lang(zh-Hant-TW) { font: 800 14pt/16.5pt "Li Sung", serif; }
3565 </pre>
3567 <p>This selects any element that has the given language — Japanese or
3568 Traditional Chinese as used in Taiwan — and uses the appropriate font.
3570 </div>
3572 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3574 <p>Modern font technologies support a variety of advanced typographic and
3575 language-specific font features. Using these features, a single font can
3576 provide glyphs for a wide range of ligatures, contextual and stylistic
3577 alternates, tabular and old-style figures, small capitals, automatic
3578 fractions, swashes, and alternates specific to a given language. To allow
3579 authors control over these font capabilities, the ‘<code
3580 class=property>font-variant</code>’ property has been expanded for CSS3.
3581 It now functions as a shorthand for a set of properties that provide
3582 control over stylistic font features.
3584 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3585 selection and positioning</h3>
3587 <p>Simple fonts used for displaying Latin text use a very basic processing
3588 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3589 which maps each character to a glyph for that character. Glyphs for
3590 subsequent characters are simply placed one after the other along a run of
3591 text. Modern font formats such as OpenType and AAT (Apple Advanced
3592 Typography) use a richer processing model. The glyph for a given character
3593 can be chosen and positioned not just based on the codepoint of the
3594 character itself, but also on adjacent characters as well as the language,
3595 script, and features enabled for the text. Font features may be required
3596 for specific scripts, or recommended as enabled by default or they might
3597 be stylistic features meant to be used under author control.
3599 <p>For a good visual overview of these features, see the <a
3600 href="#OPENTYPE-FONT-GUIDE"
3601 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3602 For a detailed description of glyph processing for OpenType fonts, see <a
3603 href="#WINDOWS-GLYPH-PROC"
3604 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3606 <p>Stylistic font features can be classified into two broad categories:
3607 ones that affect the harmonization of glyph shapes with the surrounding
3608 context, such as kerning and ligature features, and ones such as the
3609 small-caps, subscript/superscript and alternate features that affect shape
3610 selection.
3612 <p>The subproperties of <a href="#propdef-font-variant"
3613 title="font-variant!!property">‘<code
3614 class=property>font-variant</code>’</a> listed below are used to control
3615 these stylistic font features. They do not control features that are
3616 required for displaying certain scripts, such as the OpenType features
3617 used when displaying Arabic or Indic language text. They affect glyph
3618 selection and positioning, but do not affect font selection as described
3619 in the font matching section (except in cases required for compatibility
3620 with CSS 2.1).
3622 <p>To assure consistent behavior across user agents, the equivalent
3623 OpenType property settings are listed for individual properties and are
3624 normative. When using other font formats these should be used as a
3625 guideline to map CSS font feature property values to specific font
3626 features.
3628 <h3 id=language-specific-support><span class=secno>6.2
3629 </span>Language-specific display</h3>
3631 <p>OpenType also supports language-specific glyph selection and
3632 positioning, so that text can be displayed correctly in cases where the
3633 language dictates a specific display behavior. Many languages share a
3634 common script, but the shape of certain letters can vary across those
3635 languages. For example, certain Cyrillic letters have different shapes in
3636 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3637 with an explicit fi-ligature that lacks a dot on the "i". However, in
3638 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3639 important to not use this ligature or use a specialized version that
3640 contains a dot over the "i". The example below shows language-specific
3641 variations based on stylistic traditions found in Spanish, Italian and
3642 French orthography:
3644 <div class=featex><img alt="language specific forms, spanish"
3645 src=locl-1.png></div>
3647 <div class=featex><img alt="language specific forms, italian"
3648 src=locl-2.png></div>
3650 <div class=featex><img alt="language specific forms, french"
3651 src=locl-3.png></div>
3653 <p>If the content language of the element is known according to the rules
3654 of the <a
3655 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3656 language</a>, user agents are required to infer the OpenType language
3657 system from the content language and use that when selecting and
3658 positioning glyphs using an OpenType font.
3660 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3661 declare the OpenType language to be used, for example when displaying text
3662 in a given language that uses the typographic conventions of another
3663 language or when the font does not explicitly support a given language but
3664 supports a language that shares common typographic conventions. The ‘<a
3665 href="#propdef-font-language-override"><code
3666 class=property>font-language-override</code></a>’ property is used for
3667 this purpose.</p>
3668 <!-- prop: font-kerning -->
3670 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3671 href="#propdef-font-kerning">font-kerning</a> property</h3>
3673 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3674 <tbody>
3675 <tr>
3676 <td>Name:
3678 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3680 <tr>
3681 <td>Value:
3683 <td><a href="#font-kerning-auto-value"
3684 title="auto!!font-kerning">auto</a> | <a
3685 href="#font-kerning-normal-value"
3686 title="normal!!font-kerning">normal</a> | <a
3687 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3689 <tr>
3690 <td>Initial:
3692 <td>auto
3694 <tr>
3695 <td>Applies to:
3697 <td>all elements
3699 <tr>
3700 <td>Inherited:
3702 <td>yes
3704 <tr>
3705 <td>Percentages:
3707 <td>N/A
3709 <tr>
3710 <td>Media:
3712 <td>visual
3714 <tr>
3715 <td>Computed value:
3717 <td>as specified
3719 <tr>
3720 <td>Animatable:
3722 <td>no
3723 </table>
3725 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3726 property controls metric kerning, kerning that utilizes adjustment data
3727 contained in the font.
3729 <dl>
3730 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3732 <dd>Specifies that kerning is applied at the discretion of the user agent
3734 <dt><dfn id=font-kerning-normal-value
3735 title="normal!!font-kerning">normal</dfn>
3737 <dd>Specifies that kerning is applied
3739 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3741 <dd>Specifies that kerning is not applied
3742 </dl>
3744 <p>For fonts that do not include kerning data this property will have no
3745 visible effect. When rendering with OpenType fonts, the <a
3746 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3747 specification suggests that kerning be enabled by default. When kerning is
3748 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3749 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3750 instead). User agents must also support fonts that only support kerning
3751 via data contained in a <span class=tag>kern</span> font table, as
3752 detailed in the OpenType specification. If the ‘<code
3753 class=property>letter-spacing</code>’ property is defined, kerning
3754 adjustments are considered part of the default spacing and letter spacing
3755 adjustments are made after kerning has been applied.
3757 <p>When set to ‘<code class=property>auto</code>’, user agents can
3758 determine whether to apply kerning or not based on a number of factors:
3759 text size, script, or other factors that influence text processing speed.
3760 Authors who want proper kerning should use <a
3761 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3762 class=property>normal</code>’</a> to explicitly enable kerning.
3763 Likewise, some authors may prefer to disable kerning in situations where
3764 performance is more important than precise appearance. However, in
3765 well-designed modern implementations the use of kerning generally does not
3766 have a large impact on text rendering speed.</p>
3767 <!-- prop: font-variant-ligatures -->
3769 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3770 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3771 property</h3>
3773 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3774 <tbody>
3775 <tr>
3776 <td>Name:
3778 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3780 <tr>
3781 <td>Value:
3783 <td><a href="#font-variant-ligatures-normal-value"
3784 title="normal!!font-variant-ligatures">normal</a> | <a
3785 href="#font-variant-ligatures-none-value"
3786 title="none!!font-variant-ligatures">none</a> | [ <a
3787 href="#common-lig-values"><var><common-lig-values></var></a> ||
3788 <a
3789 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3790 || <a
3791 href="#historical-lig-values"><var><historical-lig-values></var></a>
3792 || <a
3793 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3794 ]
3796 <tr>
3797 <td>Initial:
3799 <td>normal
3801 <tr>
3802 <td>Applies to:
3804 <td>all elements
3806 <tr>
3807 <td>Inherited:
3809 <td>yes
3811 <tr>
3812 <td>Percentages:
3814 <td>N/A
3816 <tr>
3817 <td>Media:
3819 <td>visual
3821 <tr>
3822 <td>Computed value:
3824 <td>as specified
3826 <tr>
3827 <td>Animatable:
3829 <td>no
3830 </table>
3832 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3833 more harmonized forms.
3835 <pre
3836 class=prod><dfn id=common-lig-values><var><common-lig-values></var></dfn> = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
3838 <pre
3839 class=prod><dfn id=discretionary-lig-values><var><discretionary-lig-values></var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
3841 <pre
3842 class=prod><dfn id=historical-lig-values><var><historical-lig-values></var></dfn> = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
3844 <pre
3845 class=prod><dfn id=contextual-alt-values><var><contextual-alt-values></var></dfn> = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
3847 <p>Individual values have the following meanings:
3849 <dl>
3850 <dt><dfn id=font-variant-ligatures-normal-value
3851 title="normal!!font-variant-ligatures">normal</dfn>
3853 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3854 title="normal!!font-variant-ligatures">‘<code
3855 class=property>normal</code>’</a> specifies that common default
3856 features are enabled, <a href="#font-feature-resolution">as described in
3857 detail in the next section</a>. For OpenType fonts, common ligatures and
3858 contextual forms are on by default, discretionary and historical
3859 ligatures are not.
3861 <dt><dfn id=font-variant-ligatures-none-value
3862 title="none!!font-variant-ligatures">none</dfn>
3864 <dd>Specifies that all types of ligatures and contextual forms covered by
3865 this property are explicitly disabled. In situations where ligatures are
3866 not considered necessary, this may improve the speed of text rendering.
3868 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3870 <dd>Enables display of common ligatures (OpenType features: <span
3871 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3872 enabled by default.
3873 </dl>
3875 <div class=featex><img alt="common ligature example" src=liga.png></div>
3877 <dl>
3878 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3880 <dd>Disables display of common ligatures (OpenType features: <span
3881 class=tag>liga, clig</span>).
3883 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3885 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3886 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3887 decided by the type designer, so authors will need to refer to the
3888 documentation of a given font to understand which ligatures are
3889 considered discretionary.
3890 </dl>
3892 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3894 <dl>
3895 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3897 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3898 class=tag>dlig</span>).
3900 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3902 <dd>Enables display of historical ligatures (OpenType feature: <span
3903 class=tag>hlig</span>).
3904 </dl>
3906 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3908 <dl>
3909 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3911 <dd>Disables display of historical ligatures (OpenType feature: <span
3912 class=tag>hlig</span>).
3914 <dt><dfn id=contextual>contextual</dfn>
3916 <dd>Enables display of contextual alternates (OpenType feature: <span
3917 class=tag>calt</span>). Although not strictly a ligature feature, like
3918 ligatures this feature is commonly used to harmonize the shapes of glyphs
3919 with the surrounding context. For OpenType fonts, this feature is on by
3920 default.
3921 </dl>
3923 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3925 <dl>
3926 <dt><dfn id=no-contextual>no-contextual</dfn>
3928 <dd>Disables display of contextual alternates (OpenType feature: <span
3929 class=tag>calt</span>).
3930 </dl>
3932 <p>Required ligatures, needed for correctly rendering complex scripts, are
3933 not affected by the settings above, including ‘<code
3934 class=property>none</code>’ (OpenType feature: <span
3935 class=tag>rlig</span>).</p>
3936 <!-- prop: font-variant-position -->
3938 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3939 and superscript forms: the <a
3940 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3942 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3943 <tbody>
3944 <tr>
3945 <td>Name:
3947 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3949 <tr>
3950 <td>Value:
3952 <td><a href="#font-variant-position-normal-value"
3953 title="normal!!font-variant-position">normal</a> | <a
3954 href="#sub">sub</a> | <a href="#super">super</a>
3956 <tr>
3957 <td>Initial:
3959 <td>normal
3961 <tr>
3962 <td>Applies to:
3964 <td>all elements
3966 <tr>
3967 <td>Inherited:
3969 <td>yes
3971 <tr>
3972 <td>Percentages:
3974 <td>N/A
3976 <tr>
3977 <td>Media:
3979 <td>visual
3981 <tr>
3982 <td>Computed value:
3984 <td>as specified
3986 <tr>
3987 <td>Animatable:
3989 <td>no
3990 </table>
3992 <p>This property is used to enable typographic subscript and superscript
3993 glyphs. These are alternate glyphs designed within the same em-box as
3994 default glyphs and are intended to be laid out on the same baseline as the
3995 default glyphs, with no resizing or repositioning of the baseline. They
3996 are explicitly designed to match the surrounding text and to be more
3997 readable without affecting the line height.
3999 <div class=figure><img alt="comparison between real subscript glyphs and
4000 synthesized ones" src=realsubscripts.png>
4001 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
4002 (bottom)
4003 </div>
4005 <p>Individual values have the following meanings:
4007 <dl>
4008 <dt><dfn id=font-variant-position-normal-value
4009 title="normal!!font-variant-position">normal</dfn>
4011 <dd>None of the features listed below are enabled.
4013 <dt><dfn id=sub>sub</dfn>
4015 <dd>Enables display of subscript variants (OpenType feature: <span
4016 class=tag>subs</span>).
4018 <dt><dfn id=super>super</dfn>
4020 <dd>Enables display of superscript variants (OpenType feature: <span
4021 class=tag>sups</span>).
4022 </dl>
4024 <p>Because of the semantic nature of subscripts and superscripts, when the
4025 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
4026 or ‘<a href="#super"><code class=property>super</code></a>’ for a
4027 given contiguous run of text, if a variant glyph is not available for all
4028 the characters in the run, simulated glyphs must be synthesized for all
4029 characters using reduced forms of the glyphs that would be used without
4030 this feature applied. This is done per run to avoid a mixture of variant
4031 glyphs and synthesized ones that would not align correctly. In the case of
4032 OpenType fonts that lack subscript or superscript glyphs for a given
4033 character, user agents must use the appropriate subscript and superscript
4034 metrics specified in the selected font's <a
4035 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
4036 table</a> <a href="#OPENTYPE"
4037 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
4038 and offset of the synthesized substitutes.
4040 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
4041 using superscript metrics" src=superscript-alt-synth.png>
4042 <p class=caption>Superscript alternate glyph (left), synthesized
4043 superscript glyphs (middle), and incorrect mixture of the two (right)
4044 </div>
4046 <p>In situations where text decorations are only applied to runs of text
4047 containing superscript or subscript glyphs, the synthesized glyphs must be
4048 used to avoid problems with the placement of decorations.
4050 <p>In the past, user agents have used font-size and vertical-align to
4051 simulate subscripts and superscripts for the <code title="HTML sub
4052 element">sub</code> and <code title="HTML sup element">sup</code>
4053 elements. To allow a backwards compatible way of defining subscripts and
4054 superscripts, it is recommended that authors use conditional rules <a
4055 href="#CSS3-CONDITIONAL"
4056 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
4057 older user agents will still render subscripts and superscripts via the
4058 older mechanism.
4060 <p>Authors should note that fonts typically only provide subscript and
4061 superscript glyphs for a subset of all characters supported by the font.
4062 For example, while subscript and superscript glyphs are often available
4063 for Latin numbers, glyphs for punctuation and letter characters are less
4064 frequently provided. The synthetic fallback rules defined for this
4065 property assure that subscripts and superscripts will always appear but
4066 the appearance may not match author expectations if the font used does not
4067 provide the appropriate alternate glyph for all characters contained in a
4068 subscript or superscript.
4070 <p>This property is not cumulative. Applying it to elements within a
4071 subscript or superscript won't nest the placement of a subscript or
4072 superscript glyph. Images contained within text runs where the value of
4073 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
4074 or ‘<a href="#super"><code class=property>super</code></a>’ will be
4075 drawn just as they would if the value was <a
4076 href="#font-variant-position-normal-value"
4077 title="normal!!font-variant-position">‘<code
4078 class=property>normal</code>’</a>.</p>
4079 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
4080 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
4082 <p>Because of these limitations, ‘<a
4083 href="#propdef-font-variant-position"><code
4084 class=property>font-variant-position</code></a>’ is not recommended for
4085 use in user agent stylesheets. Authors should use it in cases where
4086 subscripts or superscripts will only contain the narrow range of
4087 characters supported by the fonts specified.
4089 <p class=note>The variant glyphs use the same baseline as the default
4090 glyphs would use. There is no shift in the placement along the baseline,
4091 so the use of variant glyphs doesn't affect the height of the inline box
4092 or alter the height of the linebox. This makes superscript and subscript
4093 variants ideal for situations where it's important that leading remain
4094 constant, such as in multi-column layout.
4096 <div class=example>
4097 <p>A typical user agent default style for the <a class=tag
4098 href="#sub">sub</a> element:</p>
4100 <pre>sub {
4101 vertical-align: sub;
4102 font-size: smaller;
4103 line-height: normal;
4104 }
4105 </pre>
4107 <p>Using font-variant-position to specify typographic subscripts in a way
4108 that will still show subscripts in older user agents:</p>
4110 <pre>@supports ( font-variant-position: sub ) {
4112 sub {
4113 vertical-align: baseline;
4114 font-size: 100%;
4115 line-height: inherit;
4116 font-variant-position: sub;
4117 }
4119 }
4120 </pre>
4122 <p>User agents that support the ‘<a
4123 href="#propdef-font-variant-position"><code
4124 class=property>font-variant-position</code></a>’ property will select a
4125 subscript variant glyph and render this without adjusting the baseline or
4126 font-size. Older user agents will ignore the ‘<a
4127 href="#propdef-font-variant-position"><code
4128 class=property>font-variant-position</code></a>’ property definition
4129 and use the standard defaults for subscripts.</p>
4130 </div>
4131 <!-- prop: font-variant-caps -->
4133 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4134 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4136 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4137 <tbody>
4138 <tr>
4139 <td>Name:
4141 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4143 <tr>
4144 <td>Value:
4146 <td><a href="#font-variant-caps-normal-value"
4147 title="normal!!font-variant-caps">normal</a> | <a
4148 href="#small-caps">small-caps</a> | <a
4149 href="#all-small-caps">all-small-caps</a> | <a
4150 href="#petite-caps">petite-caps</a> | <a
4151 href="#all-petite-caps">all-petite-caps</a> | <a
4152 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4154 <tr>
4155 <td>Initial:
4157 <td>normal
4159 <tr>
4160 <td>Applies to:
4162 <td>all elements
4164 <tr>
4165 <td>Inherited:
4167 <td>yes
4169 <tr>
4170 <td>Percentages:
4172 <td>N/A
4174 <tr>
4175 <td>Media:
4177 <td>visual
4179 <tr>
4180 <td>Computed value:
4182 <td>as specified
4184 <tr>
4185 <td>Animatable:
4187 <td>no
4188 </table>
4190 <p>This property allows the selection of alternate glyphs used for small or
4191 petite capitals or for titling. These glyphs are specifically designed to
4192 blend well with the surrounding normal glyphs, to maintain the weight and
4193 readability which suffers when text is simply resized to fit this purpose.
4195 <p>Individual values have the following meanings:
4197 <dl>
4198 <dt><dfn id=font-variant-caps-normal-value
4199 title="normal!!font-variant-caps">normal</dfn>
4201 <dd>None of the features listed below are enabled.
4203 <dt><dfn id=small-caps>small-caps</dfn>
4205 <dd>Enables display of small capitals (OpenType feature: <span
4206 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4207 uppercase letters but are reduced to the size of lowercase letters.
4208 </dl>
4210 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4212 <dl>
4213 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4215 <dd>Enables display of small capitals for both upper and lowercase letters
4216 (OpenType features: <span class=tag>c2sc, smcp</span>).
4218 <dt><dfn id=petite-caps>petite-caps</dfn>
4220 <dd>Enables display of petite capitals (OpenType feature: <span
4221 class=tag>pcap</span>).
4223 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4225 <dd>Enables display of petite capitals for both upper and lowercase
4226 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4228 <dt><dfn id=unicase>unicase</dfn>
4230 <dd>Enables display of mixture of small capitals for uppercase letters
4231 with normal lowercase letters (OpenType feature: <span
4232 class=tag>unic</span>).
4234 <dt><dfn id=titling-caps>titling-caps</dfn>
4236 <dd>Enables display of titling capitals (OpenType feature: <span
4237 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4238 use with lowercase letters. When used in all uppercase titling sequences
4239 they can appear too strong. Titling capitals are designed specifically
4240 for this situation.
4241 </dl>
4243 <p>The availability of these glyphs is based on whether a given feature is
4244 defined or not in the feature list of the font. User agents can optionally
4245 decide this on a per-script basis but should explicitly not decide this on
4246 a per-character basis.
4248 <p>Some fonts may only support a subset or none of the features described
4249 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4250 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4251 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4252 is specified but small-caps glyphs are not available for a given font,
4253 user agents should simulate a small-caps font, for example by taking a
4254 normal font and replacing the glyphs for lowercase letters with scaled
4255 versions of the glyphs for uppercase characters (replacing the glyphs for
4256 both upper and lowercase letters in the case of ‘<a
4257 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4259 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4260 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4261 width=512>
4262 <p class=caption>Synthetic vs. real small-caps
4263 </div>
4265 <p>To match the surrounding text, a font may provide alternate glyphs for
4266 caseless characters when these features are enabled but when a user agent
4267 simulates small capitals, it must not attempt to simulate alternates for
4268 codepoints which are considered caseless.
4270 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4271 characters with small-caps, all-small-caps enabled" class=hires
4272 src=small-capitals-variations.png width=418>
4273 <p class=caption>Caseless characters with small-caps, all-small-caps
4274 enabled
4275 </div>
4277 <p>If either ‘<a href="#petite-caps"><code
4278 class=property>petite-caps</code></a>’ or ‘<a
4279 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4280 is specified for a font that doesn't support these features, the property
4281 behaves as if ‘<a href="#small-caps"><code
4282 class=property>small-caps</code></a>’ or ‘<a
4283 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4284 respectively, had been specified. If ‘<a href="#unicase"><code
4285 class=property>unicase</code></a>’ is specified for a font that doesn't
4286 support that feature, the property behaves as if ‘<a
4287 href="#small-caps"><code class=property>small-caps</code></a>’ was
4288 applied only to lowercased uppercase letters. If ‘<a
4289 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4290 specified with a font that does not support this feature, this property
4291 has no visible effect. When simulated small capital glyphs are used, for
4292 scripts that lack uppercase and lowercase letters, ‘<a
4293 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4294 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4295 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4296 ‘<a href="#all-petite-caps"><code
4297 class=property>all-petite-caps</code></a>’ and ‘<a
4298 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4299 effect.
4301 <p>When casing transforms are used to simulate small capitals, the casing
4302 transformations must match those used for the <span
4303 class=property>‘<code class=property>text-transform</code>’</span>
4304 property.
4306 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4307 replace glyphs in a small-caps font so that the text appears in all
4308 uppercase letters.
4310 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4311 all-small-caps in acronym-laden text" class=hires
4312 src=acronym-laden-text.png width=596>
4313 <p class=caption>Using small capitals to improve readability in
4314 acronym-laden text
4315 </div>
4317 <div class=example>
4318 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4320 <pre>blockquote { font-style: italic; }
4321 blockquote:first-line { font-variant: small-caps; }
4323 <blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none; border: none;">I'll be honor-bound to slap them like a haddock.</a></blockquote>
4324 </pre>
4325 </div>
4326 <!-- prop: font-variant-numeric -->
4328 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4329 formatting: the <a
4330 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4332 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4333 <tbody>
4334 <tr>
4335 <td>Name:
4337 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4339 <tr>
4340 <td>Value:
4342 <td><a href="#font-variant-numeric-normal-value"
4343 title="normal!!font-variant-numeric">normal</a> | [ <a
4344 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4345 || <a
4346 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4347 || <a
4348 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4349 || <a href="#ordinal">ordinal</a> || <a
4350 href="#slashed-zero">slashed-zero</a> ]
4352 <tr>
4353 <td>Initial:
4355 <td>normal
4357 <tr>
4358 <td>Applies to:
4360 <td>all elements
4362 <tr>
4363 <td>Inherited:
4365 <td>yes
4367 <tr>
4368 <td>Percentages:
4370 <td>N/A
4372 <tr>
4373 <td>Media:
4375 <td>visual
4377 <tr>
4378 <td>Computed value:
4380 <td>as specified
4382 <tr>
4383 <td>Animatable:
4385 <td>no
4386 </table>
4388 <p>Specifies control over numerical forms. The example below shows how some
4389 of these values can be combined to influence the rendering of tabular data
4390 with fonts that support these features. Within normal paragraph text,
4391 proportional numbers are used while tabular numbers are used so that
4392 columns of numbers line up properly:
4394 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4395 number styles" src=numberstyles.png>
4396 <p class=caption>Using number styles
4397 </div>
4399 <p>Possible combinations:
4401 <pre
4402 class=prod><dfn id=numeric-figure-values><var><numeric-figure-values></var></dfn> = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
4404 <pre
4405 class=prod><dfn id=numeric-spacing-values><var><numeric-spacing-values></var></dfn> = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
4407 <pre
4408 class=prod><dfn id=numeric-fraction-values><var><numeric-fraction-values></var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
4410 <p>Individual values have the following meanings:
4412 <dl>
4413 <dt><dfn id=font-variant-numeric-normal-value
4414 title="normal!!font-variant-numeric">normal</dfn>
4416 <dd>None of the features listed below are enabled.
4418 <dt><dfn id=lining-nums>lining-nums</dfn>
4420 <dd>Enables display of lining numerals (OpenType feature: <span
4421 class=tag>lnum</span>).
4423 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4425 <dd>Enables display of old-style numerals (OpenType feature: <span
4426 class=tag>onum</span>).
4428 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4430 <dd>Enables display of proportional numerals (OpenType feature: <span
4431 class=tag>pnum</span>).
4433 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4435 <dd>Enables display of tabular numerals (OpenType feature: <span
4436 class=tag>tnum</span>).
4438 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4440 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4441 class=tag>frac</span>).
4442 </dl>
4444 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4446 <dl>
4447 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4449 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4450 class=tag>afrc</span>).
4451 </dl>
4453 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4455 <dl>
4456 <dt><dfn id=ordinal>ordinal</dfn>
4458 <dd>Enables display of letter forms used with ordinal numbers (OpenType
4459 feature: <span class=tag>ordn</span>).
4460 </dl>
4462 <div class=featex><img alt="ordinals example" src=ordinals.png></div>
4464 <dl>
4465 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4467 <dd>Enables display of slashed zeros (OpenType feature: <span
4468 class=tag>zero</span>).
4469 </dl>
4471 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4473 <div class=example id=ordinal-example>
4474 <p>In the case of ‘<a href="#ordinal"><code
4475 class=property>ordinal</code></a>’, although ordinal forms are often
4476 the same as superscript forms, they are marked up differently.</p>
4478 <p>For superscripts, the variant property is only applied to the
4479 sub-element containing the superscript:</p>
4481 <pre>
4482 sup { font-variant-position: super; }
4483 x<sup>2</sup>
4484 </pre>
4486 <p>For ordinals, the variant property is applied to the entire ordinal
4487 number rather than just to the suffix (or to the containing paragraph):</p>
4489 <pre>
4490 .ordinal { font-variant-numeric: ordinal; }
4491 <span class="ordinal">17th</span>
4492 </pre>
4494 <p>In this case only the "th" will appear in ordinal form, the digits will
4495 remain unchanged. Depending upon the typographic traditions used in a
4496 given language, ordinal forms may differ from superscript forms. In
4497 Italian, for example, ordinal forms sometimes include an underline in the
4498 ordinal design.</p>
4499 </div>
4501 <div class=example id=steak-marinade>
4502 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4503 and old-style numerals:</p>
4505 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4507 <h4>Steak marinade:</h4>
4508 <ul>
4509 <li><span class="amount">2</span> tbsp olive oil</li>
4510 <li><span class="amount">1</span> tbsp lemon juice</li>
4511 <li><span class="amount">1</span> tbsp soy sauce</li>
4512 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4513 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4514 <li>Salt &amp; pepper</li>
4515 </ul>
4517 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4518 for a few hours or overnight.</p>
4519 </pre>
4521 <p>Note that the fraction feature is only applied to values not the entire
4522 paragraph. Fonts often implement this feature using contextual rules
4523 based on the use of the slash (‘<code class=css>/</code>’) character.
4524 As such, it's not suitable for use as a paragraph-level style.</p>
4525 </div>
4526 <!-- prop: font-variant-alternates -->
4528 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4529 and swashes: the <a
4530 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4531 property</h3>
4533 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4534 <tbody>
4535 <tr>
4536 <td>Name:
4538 <td><dfn
4539 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4541 <tr>
4542 <td>Value:
4544 <td>normal | [ <a href="#stylistic"
4545 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4546 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4547 title=styleset>styleset(<feature-value-name> #)</a> || <a
4548 href="#character-variant"
4549 title=character-variant>character-variant(<feature-value-name>
4550 #)</a> || <a href="#swash"
4551 title=swash>swash(<feature-value-name>)</a> || <a
4552 href="#ornaments"
4553 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4554 href="#annotation"
4555 title=annotation>annotation(<feature-value-name>)</a> ]
4557 <tr>
4558 <td>Initial:
4560 <td>normal
4562 <tr>
4563 <td>Applies to:
4565 <td>all elements
4567 <tr>
4568 <td>Inherited:
4570 <td>yes
4572 <tr>
4573 <td>Percentages:
4575 <td>N/A
4577 <tr>
4578 <td>Media:
4580 <td>visual
4582 <tr>
4583 <td>Computed value:
4585 <td>as specified
4587 <tr>
4588 <td>Animatable:
4590 <td>no
4591 </table>
4593 <p>For any given character, fonts can provide a variety of alternate glyphs
4594 in addition to the default glyph for that character. This property
4595 provides control over the selection of these alternate glyphs.
4597 <p>For many of the property values listed below, several different
4598 alternate glyphs are available. How many alternates are available and what
4599 they represent is font-specific, so these are each marked <dfn
4600 id=font-specific>font specific</dfn> in the value definitions below.
4601 Because the nature of these alternates is font-specific, the <a
4602 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4603 rule is used to define values for a specific font family or set of
4604 families that associate a font-specific numeric
4605 <code><feature-index></code> with a custom
4606 <code><feature-value-name></code>, which is then used in this
4607 property to select specific alternates:
4609 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4611 p {
4612 font-family: Noble Script;
4613 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4614 }</pre>
4616 <p>When a particular <code><feature-value-name></code> has not been
4617 defined for a given family or for a particular feature type, the computed
4618 value must be the same as if it had been defined. However, property values
4619 that contain these undefined <code><feature-value-name></code>
4620 identifiers must be ignored when choosing glyphs.
4622 <pre>/* these two style rules are effectively the same */
4623 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4624 p { font-variant-alternates: normal; }
4625 </pre>
4627 <p>This allows values to be defined and used for a given set of font
4628 families but ignored if fallback occurs, since the font family name would
4629 be different. If a given value is outside the range supported by a given
4630 font, the value is ignored. These values never apply to generic font
4631 families.
4633 <p>Individual values have the following meanings:
4635 <dl>
4636 <dt><dfn id=font-variant-alternates-normal-value
4637 title="normal!!font-variant-alternates">normal</dfn>
4639 <dd>None of the features listed below are enabled.
4641 <dt><dfn id=historical-forms>historical-forms</dfn>
4643 <dd>Enables display of historical forms (OpenType feature: <span
4644 class=tag>hist</span>).
4645 </dl>
4647 <div class=featex><img alt="historical form example" src=hist.png></div>
4649 <dl>
4650 <dt><dfn id=stylistic
4651 title=stylistic>stylistic(<feature-value-name>)</dfn>
4653 <dd>Enables display of stylistic alternates (<a
4654 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4655 class=tag>salt <feature-index></span>).
4656 </dl>
4658 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4660 <dl>
4661 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4662 #)</dfn>
4664 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4665 specific</em></a>, OpenType feature: <span
4666 class=tag>ss<feature-index></span> OpenType currently defines <span
4667 class=tag>ss01</span> through <span class=tag>ss20</span>).
4668 </dl>
4670 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4672 <dl>
4673 <dt><dfn id=character-variant
4674 title=character-variant>character-variant(<feature-value-name>
4675 #)</dfn>
4677 <dd>Enables display of specific character variants (<a
4678 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4679 class=tag>cv<feature-index></span> OpenType currently defines <span
4680 class=tag>cv01</span> through <span class=tag>cv99</span>).
4682 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4684 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4685 specific</em></a>, OpenType feature: <span class=tag>swsh
4686 <feature-index>, cswh <feature-index></span>).
4687 </dl>
4689 <div class=featex><img alt="swash example" src=swsh.png></div>
4691 <dl>
4692 <dt><dfn id=ornaments
4693 title=ornaments>ornaments(<feature-value-name>)</dfn>
4695 <dd>Enables replacement of default glyphs with ornaments, if provided in
4696 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4697 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4698 may offer ornament glyphs as alternates for a wide collection of
4699 characters; however, displaying arbitrary characters (e.g.,
4700 alphanumerics) as ornaments is poor practice as it distorts the semantics
4701 of the data. Font designers are encouraged to encode all ornaments
4702 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4703 alternates for the bullet character (U+2022) to allow authors to select
4704 the desired glyph using ‘<a href="#ornaments"><code
4705 class=property>ornaments</code></a>’.
4706 </dl>
4708 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4710 <dl>
4711 <dt><dfn id=annotation
4712 title=annotation>annotation(<feature-value-name>)</dfn>
4714 <dd>Enables display of alternate annotation forms (<a
4715 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4716 class=tag>nalt <feature-index></span>).
4717 </dl>
4719 <div class=featex><img alt="alternate annotation form example"
4720 src=nalt.png></div>
4722 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4723 specific alternates: the <dfn id=at-font-feature-values-rule
4724 style="font-weight: inherit; font-style:
4725 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4727 <p>Several of the possible values of ‘<a
4728 href="#propdef-font-variant-alternates"><code
4729 class=property>font-variant-alternates</code></a>’ listed above are
4730 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4731 features fonts may define not just a single glyph but a set of alternate
4732 glyphs with an index to select a given alternate. Since these are font
4733 family specific, the <a
4734 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4735 rule is used to define named values for these indices for a given family.
4737 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4738 reference section</a> for a description of the interfaces used to modify
4739 these rules via the CSS Object Model.
4741 <div class=example>
4742 <p>In the case of the swash Q in the example shown above, the swash could
4743 be specified using these style rules:</p>
4745 <pre>
4747 @font-feature-values Jupiter Sans {
4748 @swash {
4749 delicate: 1;
4750 flowing: 2;
4751 }
4752 }
4754 h2 { font-family: Jupiter Sans, sans-serif; }
4756 /* show the second swash variant in h2 headings */
4757 h2:first-letter { font-variant-alternates: swash(flowing); }
4759 <h2>Quick</h2></pre>
4761 <p>When Jupiter Sans is present, the second alternate swash alternate will
4762 be displayed. When not present, no swash character will be shown, since
4763 the specific named value "flowing" is only defined for the Jupiter Sans
4764 family. The @-mark indicates the name of the property value for which a
4765 named value can be used. The name "flowing" is chosen by the author. The
4766 index that represents each alternate is defined within a given font's
4767 data.</p>
4768 </div>
4770 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4772 <p>An <a
4773 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4774 rule is composed of a list of font families followed by a block containing
4775 individual <a href="#featurevalueblock"><i
4776 title="feature_value_block">feature value blocks</i></a> that take the
4777 form of @-rules. Each block defines a set of named values for a specific
4778 font feature when a given set of font families is used. Effectively, they
4779 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4780 ⟨values⟩ are the numeric indices used for specific features defined
4781 for a given font.
4783 <p>In terms of the grammar, this specification defines the following
4784 productions:
4786 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4787 : <a href="#fontfeaturevaluessym"><i>FONT_FEATURE_VALUES_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilynamelist"><i>font_family_name_list</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4788 '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4789 ;
4791 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4792 : <a href="#fontfamilyname"><i>font_family_name</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ',' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilyname"><i>font_family_name</i></a> ]*
4793 ;
4795 <dfn id=fontfamilyname>font_family_name</dfn>
4796 : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>STRING</i></a> | [ <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> ]* ]
4797 ;
4799 <dfn id=featurevalueblock>feature_value_block</dfn>
4800 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4801 '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4802 ;
4804 <dfn id=featuretype>feature_type</dfn>:
4805 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4806 ;
4808 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4809 : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> ]*
4810 ;
4811 </pre>
4813 <p>The following new token is introduced:
4815 <pre>@{F}{O}{N}{T}{-}{F}{E}{A}{T}{U}{R}{E}{-}{V}{A}{L}{U}{E}{S} {return <dfn id=fontfeaturevaluessym>FONT_FEATURE_VALUES_SYM</dfn>;}
4816 </pre>
4818 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4819 value blocks</i></a> are handled as <a
4820 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4821 consist of everything up to the next block or semi-colon, whichever comes
4822 first.
4824 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4825 family list</i></a> is a comma-delimited list of <a
4826 href="#fontfamilyname"><i title="font_family_name">font family
4827 names</i></a> that match the definition of <a
4828 href="#family-name-value"><var><family-name></var></a> for the <a
4829 href="#propdef-font-family" title="font-family!!property">‘<code
4830 class=property>font-family</code>’</a> property. This means that only
4831 named font families are allowed, rules that include generic or system
4832 fonts in the list of font families are syntax errors. However, if a user
4833 agent defines a generic font to be a specific named font (e.g. Helvetica),
4834 the settings associated with that family name will be used. If syntax
4835 errors occur within the font family list, the entire rule must be ignored.
4837 <p>Within <a href="#featurevalueblock"><i
4838 title="feature_value_block">feature value blocks</i></a>, the <a
4839 href="#featuretype"><i title="feature_type">feature type</i></a> is
4840 ‘<code class=css>@</code>’ followed by the name of one of the <a
4841 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4842 href="#propdef-font-variant-alternates"><code
4843 class=property>font-variant-alternates</code></a>’ (e.g. <a
4844 href="#swash"><code>@swash</code></a>). The identifiers used within
4845 feature value definitions follow the rules of CSS user identifiers and are
4846 case-sensitive. They are unique only for a given set of font families and
4847 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4848 same identifier used with a different <a href="#featuretype"><i
4849 title="feature_type">feature type</i></a> is treated as a separate and
4850 distinct value. If the same identifier is defined mulitple times for a
4851 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4852 and font family, the last defined value is used. Values associated with a
4853 given identifier are limited to integer values 0 or greater.
4855 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4856 title="feature_value_definition">feature value definition</i></a>, such as
4857 invalid identifiers or values, the entire <a
4858 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4859 value definition</i></a> must be omitted, just as syntax errors in style
4860 declarations are handled. When the <a href="#featuretype"><i
4861 title="feature_type">feature type</i></a> is invalid, the entire
4862 associated <a href="#featurevalueblock"><i
4863 title="feature_value_block">feature value block</i></a> must be ignored.
4865 <div class=example>
4866 <p>Rules that are equivalent given syntax error handling:</p>
4868 <pre>@font-feature-values Bongo {
4869 @swash { ornate: 1; }
4870 annotation { boxed: 4; } /* should be @annotation! */
4871 @swash { double-loops: 1; flowing: -1; } /* negative value */
4872 @ornaments ; /* incomplete definition */
4873 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4874 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4875 }</pre>
4877 <p>The example above is equivalent to:</p>
4879 <pre>@font-feature-values Bongo {
4880 @swash { ornate: 1; }
4881 @swash { double-loops: 1; }
4882 @styleset { double-W: 14; sharp-terminals: 16 1; }
4883 }</pre>
4884 </div>
4886 <p>If multiple <a
4887 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4888 rules are defined for a given family, the resulting values definitions are
4889 the union of the definitions contained within these rules. This allows a
4890 set of named values to be defined for a given font family globally for a
4891 site and specific additions made per-page.
4893 <div class=example>
4894 <p>Using both site-wide and per-page feature values:</p>
4896 <pre>
4897 site.css:
4899 @font-feature-values Mercury Serif {
4900 @styleset {
4901 stacked-g: 3; /* "two-storey" versions of g, a */
4902 stacked-a: 4;
4903 }
4904 }
4906 page.css:
4908 @font-feature-values Mercury Serif {
4909 @styleset {
4910 geometric-m: 7; /* alternate version of m */
4911 }
4912 }
4914 body {
4915 font-family: Mercury Serif, serif;
4917 /* enable both the use of stacked g and alternate m */
4918 font-variant-alternates: styleset(stacked-g, geometric-m);
4919 }</pre>
4920 </div>
4922 <div class=example>
4923 <p>Using a commonly named value allows authors to use a single style rule
4924 to cover a set of fonts for which the underlying selector is different
4925 for each font. If either font in the example below is found, a circled
4926 number glyph will be used:</p>
4928 <pre>@font-feature-values Taisho Gothic {
4929 @annotation { boxed: 1; circled: 4; }
4930 }
4932 @font-feature-values Otaru Kisa {
4933 @annotation { circled: 1; black-boxed: 3; }
4934 }
4936 h3.title {
4937 /* circled form defined for both fonts */
4938 font-family: Taisho Gothic, Otaru Kisa;
4939 font-variant: annotation(circled);
4940 }</pre>
4941 </div>
4943 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4944 </span>Multi-valued feature value definitions</h4>
4946 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4947 href="#propdef-font-variant-alternates"><code
4948 class=property>font-variant-alternates</code></a>’ property values take
4949 a single value (e.g. ‘<a href="#swash"><code
4950 class=property>swash</code></a>’). The ‘<a
4951 href="#character-variant"><code
4952 class=property>character-variant</code></a>’ property value allows two
4953 values and ‘<a href="#styleset"><code
4954 class=property>styleset</code></a>’ allows an unlimited number.
4956 <p>For the styleset property value, multiple values indicate the style sets
4957 to be enabled. Values between 1 and 99 enable OpenType features <span
4958 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4959 OpenType standard only officially defines <span class=tag>ss01</span>
4960 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4961 than 99 or equal to 0 do not generate a syntax error when parsed but
4962 enable no OpenType features.
4964 <pre>@font-feature-values Mars Serif {
4965 @styleset {
4966 alt-g: 1; /* implies ss01 = 1 */
4967 curly-quotes: 3; /* implies ss03 = 1 */
4968 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4969 }
4971 @styleset {
4972 dumb: 125; /* >99, ignored */
4973 }
4975 @swash {
4976 swishy: 3 5; /* more than 1 value for swash, syntax error */
4977 }
4978 }
4980 p.codeblock {
4981 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4982 font-variant-alternates: styleset(curly-quotes, code);
4983 }</pre>
4985 <p>For character-variant, a single value between 1 and 99 indicates the
4986 enabling of OpenType feature <span class=tag>cv01</span> through <span
4987 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4988 to 0 are ignored but do not generate a syntax error when parsed but enable
4989 no OpenType features. When two values are listed, the first value
4990 indicates the feature used and the second the value passed for that
4991 feature. If more than two values are assigned to a given name, a syntax
4992 error occurs and the entire <a href="#featurevaluedefinition"><i
4993 title="feature_value_definition">feature value definition</i></a> is
4994 ignored.
4996 <pre>@font-feature-values MM Greek {
4997 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4998 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4999 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
5000 @character-variant { gamma: 12; } /* implies cv12 = 1 */
5001 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
5002 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
5003 @character-variant { silly: 105; } /* >99, ignored */
5004 @character-variant { dumb: 323 3; } /* >99, ignored */
5005 }
5007 #title {
5008 /* use the third alternate beta, first alternate gamma */
5009 font-variant-alternates: character-variant(beta-3, gamma);
5010 }
5012 p {
5013 /* zeta-2 follows zeta, implies cv20 = 2 */
5014 font-variant-alternates: character-variant(zeta, zeta-2);
5015 }
5017 .special {
5018 /* zeta follows zeta-2, implies cv20 = 3 */
5019 font-variant-alternates: character-variant(zeta-2, zeta);
5020 }</pre>
5022 <div class=figure><img alt="Matching text on Byzantine seals using
5023 character variants" src=byzantineseal.png>
5024 <p class=caption>Byzantine seal text displayed with character variants
5025 </div>
5027 <div class=example>
5028 <p>In the figure above, the text in red is rendered using a font
5029 containing character variants that mimic the character forms found on a
5030 Byzantine seal from the 8th century A.D. Two lines below is the same text
5031 displayed in a font without variants. Note the two variants for U and N
5032 used on the seal.</p>
5034 <pre>@font-feature-values Athena Ruby {
5035 @character-variant {
5036 leo-B: 2 1;
5037 leo-M: 13 3;
5038 leo-alt-N: 14 1;
5039 leo-N: 14 2;
5040 leo-T: 20 1;
5041 leo-U: 21 2;
5042 leo-alt-U: 21 4;
5043 }
5044 }
5046 p {
5047 font-variant: discretionary-ligatures,
5048 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
5049 }
5051 span.alt-N {
5052 font-variant-alternates: character-variant(leo-alt-N);
5053 }
5055 span.alt-U {
5056 font-variant-alternates: character-variant(leo-alt-U);
5057 }
5059 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
5061 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
5062 </pre>
5063 </div>
5065 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
5066 Asian text rendering: the <a
5067 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
5068 property</h3>
5070 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
5071 <tbody>
5072 <tr>
5073 <td>Name:
5075 <td><dfn
5076 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
5078 <tr>
5079 <td>Value:
5081 <td><a href="#font-variant-east-asian-normal-value"
5082 title="normal!!font-variant-east-asian">normal</a> | [ <a
5083 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5084 || <a
5085 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5086 || <a href="#ruby">ruby</a> ]
5088 <tr>
5089 <td>Initial:
5091 <td>normal
5093 <tr>
5094 <td>Applies to:
5096 <td>all elements
5098 <tr>
5099 <td>Inherited:
5101 <td>yes
5103 <tr>
5104 <td>Percentages:
5106 <td>N/A
5108 <tr>
5109 <td>Media:
5111 <td>visual
5113 <tr>
5114 <td>Computed value:
5116 <td>as specified
5118 <tr>
5119 <td>Animatable:
5121 <td>no
5122 </table>
5124 <p>Allows control of glyph substitution and sizing in East Asian text.
5126 <pre
5127 class=prod><dfn id=east-asian-variant-values><var><east-asian-variant-values></var></dfn> = [ <a href="#jis78">jis78</a> | <a href="#jis83">jis83</a> | <a href="#jis90">jis90</a> | <a href="#jis04">jis04</a> | <a href="#simplified">simplified</a> | <a href="#traditional">traditional</a> ]</pre>
5129 <pre
5130 class=prod><dfn id=east-asian-width-values><var><east-asian-width-values></var></dfn> = [ <a href="#full-width">full-width</a> | <a href="#proportional-width">proportional-width</a> ]</pre>
5132 <p>Individual values have the following meanings:
5134 <dl>
5135 <dt><dfn id=font-variant-east-asian-normal-value
5136 title="normal!!font-variant-east-asian">normal</dfn>
5138 <dd>None of the features listed below are enabled.
5140 <dt><dfn id=jis78>jis78</dfn>
5142 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
5143 class=tag>jp78</span>).
5144 </dl>
5146 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
5148 <dl>
5149 <dt><dfn id=jis83>jis83</dfn>
5151 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
5152 class=tag>jp83</span>).
5154 <dt><dfn id=jis90>jis90</dfn>
5156 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
5157 class=tag>jp90</span>).
5159 <dt><dfn id=jis04>jis04</dfn>
5161 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5162 class=tag>jp04</span>).
5163 <p>The various JIS variants reflect the glyph forms defined in different
5164 Japanese national standards. Fonts generally include glyphs defined by
5165 the most recent national standard but it's sometimes necessary to use
5166 older variants, to match signage for example.</p>
5168 <dt><dfn id=simplified>simplified</dfn>
5170 <dd>Enables rendering of simplified forms (OpenType feature: <span
5171 class=tag>smpl</span>).
5173 <dt><dfn id=traditional>traditional</dfn>
5175 <dd>Enables rendering of traditional forms (OpenType feature: <span
5176 class=tag>trad</span>).
5177 </dl>
5179 <p>The ‘<a href="#simplified"><code
5180 class=property>simplified</code></a>’ and ‘<a
5181 href="#traditional"><code class=property>traditional</code></a>’ values
5182 allow control over the glyph forms for characters which have been
5183 simplified over time but for which the older, traditional form is still
5184 used in some contexts. The exact set of characters and glyph forms will
5185 vary to some degree by context for which a given font was designed.
5187 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5189 <dl>
5190 <dt><dfn id=full-width>full-width</dfn>
5192 <dd>Enables rendering of full-width variants (OpenType feature: <span
5193 class=tag>fwid</span>).
5195 <dt><dfn id=proportional-width>proportional-width</dfn>
5197 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5198 <span class=tag>pwid</span>).
5199 </dl>
5201 <div class=featex><img alt="proportionally spaced Japanese example"
5202 src=pwid.png></div>
5204 <dl>
5205 <dt><dfn id=ruby>ruby</dfn>
5207 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5208 class=tag>ruby</span>). Since ruby text is generally smaller than the
5209 associated body text, font designers can design special glyphs for use
5210 with ruby that are more readable than scaled down versions of the default
5211 glyphs. Only glyph selection is affected, there is no associated font
5212 scaling or other change that affects line layout. The red ruby text below
5213 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5214 Note the slight difference in stroke thickness.
5215 </dl>
5217 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5219 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5220 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5221 property</h3>
5223 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5224 <tbody>
5225 <tr>
5226 <td>Name:
5228 <td><dfn id=propdef-font-variant
5229 title="font-variant!!property">font-variant</dfn>
5231 <tr>
5232 <td>Value:
5234 <td><a href="#font-variant-normal-value"
5235 title="normal!!font-variant">normal</a> | <a
5236 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5237 <a href="#common-lig-values"><var><common-lig-values></var></a>
5238 || <a
5239 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5240 || <a
5241 href="#historical-lig-values"><var><historical-lig-values></var></a>
5242 || <a
5243 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5244 || <a href="#stylistic"><var
5245 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5246 href="#historical-forms"><var>historical-forms</var></a> || <a
5247 href="#styleset"><var
5248 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5249 href="#character-variant"><var
5250 title=character-variant>character-variant(<feature-value-name>
5251 #)</var></a> || <a href="#swash"><var
5252 title=swash>swash(<feature-value-name>)</var></a> || <a
5253 href="#ornaments"><var
5254 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5255 href="#annotation"><var
5256 title=annotation>annotation(<feature-value-name>)</var></a> || [
5257 <a href="#small-caps"><i>small-caps</i></a> | <a
5258 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5259 href="#petite-caps"><i>petite-caps</i></a> | <a
5260 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5261 href="#unicase"><i>unicase</i></a> | <a
5262 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5263 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5264 || <a
5265 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5266 || <a
5267 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5268 || <a href="#ordinal"><i>ordinal</i></a> || <a
5269 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5270 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5271 || <a
5272 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5273 || <a href="#ruby"><i>ruby</i></a> ]
5275 <tr>
5276 <td>Initial:
5278 <td>normal
5280 <tr>
5281 <td>Applies to:
5283 <td>all elements
5285 <tr>
5286 <td>Inherited:
5288 <td>yes
5290 <tr>
5291 <td>Percentages:
5293 <td>see individual properties
5295 <tr>
5296 <td>Media:
5298 <td>visual
5300 <tr>
5301 <td>Computed value:
5303 <td>see individual properties
5305 <tr>
5306 <td>Animatable:
5308 <td>see individual properties
5309 </table>
5311 <p>The <a href="#propdef-font-variant"
5312 title="font-variant!!property">‘<code
5313 class=property>font-variant</code>’</a> property is a shorthand for all
5314 font-variant subproperties. The value <dfn id=font-variant-normal-value
5315 title="normal!!font-variant">‘<code
5316 class=property>normal</code>’</dfn> resets all subproperties of <a
5317 href="#propdef-font-variant" title="font-variant!!property">‘<code
5318 class=property>font-variant</code>’</a> to their inital value. The <dfn
5319 id=font-variant-none-value title="none!!font-variant">‘<code
5320 class=property>none</code>’</dfn> value sets ‘<a
5321 href="#propdef-font-variant-ligatures"><code
5322 class=property>font-variant-ligatures</code></a>’ to ‘<code
5323 class=property>none</code>’ and resets all other font feature properties
5324 to their initial value. Like other shorthands, using <a
5325 href="#propdef-font-variant" title="font-variant!!property">‘<code
5326 class=property>font-variant</code>’</a> resets unspecified <a
5327 href="#propdef-font-variant" title="font-variant!!property">‘<code
5328 class=property>font-variant</code>’</a> subproperties to their initial
5329 values. It does not reset the values of either ‘<a
5330 href="#propdef-font-language-override"><code
5331 class=property>font-language-override</code></a>’ or <a
5332 href="#propdef-font-feature-settings"
5333 title="font-feature-settings!!property">‘<code
5334 class=property>font-feature-settings</code>’</a>.
5336 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5337 font feature settings control: the <a
5338 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5340 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5341 <tbody>
5342 <tr>
5343 <td>Name:
5345 <td><dfn id=propdef-font-feature-settings
5346 title="font-feature-settings!!property">font-feature-settings</dfn>
5348 <tr>
5349 <td>Value:
5351 <td><a href="#font-feature-settings-normal-value"
5352 title="normal!!font-feature-settings">normal</a> | <a
5353 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5355 <tr>
5356 <td>Initial:
5358 <td>normal
5360 <tr>
5361 <td>Applies to:
5363 <td>all elements
5365 <tr>
5366 <td>Inherited:
5368 <td>yes
5370 <tr>
5371 <td>Percentages:
5373 <td>N/A
5375 <tr>
5376 <td>Media:
5378 <td>visual
5380 <tr>
5381 <td>Computed value:
5383 <td>as specified
5385 <tr>
5386 <td>Animatable:
5388 <td>no
5389 </table>
5391 <p>This property provides low-level control over OpenType font features. It
5392 is intended as a way of providing access to font features that are not
5393 widely used but are needed for a particular use case.
5395 <p>Authors should generally use <a href="#propdef-font-variant"
5396 title="font-variant!!property">‘<code
5397 class=property>font-variant</code>’</a> and its related subproperties
5398 whenever possible and only use this property for special cases where its
5399 use is the only way of accessing a particular infrequently used font
5400 feature.
5402 <pre>/* enable small caps and use second swash alternate */
5403 font-feature-settings: "smcp", "swsh" 2;</pre>
5405 <p>A value of <dfn id=font-feature-settings-normal-value
5406 title="normal!!font-feature-settings">‘<code
5407 class=property>normal</code>’</dfn> means that no change in glyph
5408 selection or positioning occurs due to this property.
5410 <p>Feature tag values have the following syntax:
5412 <pre
5413 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5415 <p>The <string> is a case-sensitive OpenType feature tag. As
5416 specified in the OpenType specification, feature tags contain four ASCII
5417 characters. Tag strings longer or shorter than four characters, or
5418 containing characters outside the U+20–7E codepoint range are invalid.
5419 Feature tags need only match a feature tag defined in the font, so they
5420 are not limited to explicitly registered OpenType features. Fonts defining
5421 custom feature tags should follow the <a
5422 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5423 rules</a> defined in the OpenType specification <a
5424 href="#OPENTYPE-FEATURES"
5425 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5427 <p>Feature tags not present in the font are ignored; a user agent must not
5428 attempt to synthesize fallback behavior based on these feature tags. The
5429 one exception is that user agents may synthetically support the <span
5430 class=tag>kern</span> feature with fonts that contain kerning data in the
5431 form of a ‘<code class=property>kern</code>’ table but lack <span
5432 class=tag>kern</span> feature support in the ‘<code
5433 class=property>GPOS</code>’ table.
5435 <p class=note>In general, authors should use the ‘<a
5436 href="#propdef-font-kerning"><code
5437 class=property>font-kerning</code></a>’ property to explicitly enable or
5438 disable kerning since this property always affects fonts with either type
5439 of kerning data.
5441 <p>If present, a value indicates an index used for glyph selection. An
5442 <integer> value must be 0 or greater. A value of 0 indicates that
5443 the feature is disabled. For boolean features, a value of 1 enables the
5444 feature. For non-boolean features, a value of 1 or greater enables the
5445 feature and indicates the feature selection index. A value of ‘<code
5446 class=property>on</code>’ is synonymous with 1 and ‘<code
5447 class=property>off</code>’ is synonymous with 0. If the value is
5448 omitted, a value of 1 is assumed.
5450 <pre>
5451 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5452 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5453 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5454 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5455 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5456 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5457 font-feature-settings: "silly" off; /* invalid, tag too long */
5458 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5459 font-feature-settings: dlig; /* invalid, tag must be a string */
5460 </pre>
5462 <p>When values greater than the range supported by the font are specified,
5463 the behavior is explicitly undefined. For boolean features, in general
5464 these will enable the feature. For non-boolean features, out of range
5465 values will in general be equivalent to a 0 value. However, in both cases
5466 the exact behavior will depend upon the way the font is designed
5467 (specifically, which type of lookup is used to define the feature).
5469 <p>Although specifically defined for OpenType feature tags, feature tags
5470 for other modern font formats that support font features may be added in
5471 the future. Where possible, features defined for other font formats should
5472 attempt to follow the pattern of registered OpenType tags.
5474 <div class=example>
5475 <p>The Japanese text below will be rendered with half-width kana
5476 characters:</p>
5478 <pre lang=ja>
5479 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5481 <p>毎日<a href="http://images.google.com/images?q=%E3%82%AB%E3%83%AC%E3%83%BC" style="text-decoration: none;">カレー</a>食べてるのに、飽きない</p>
5482 </pre>
5483 </div>
5485 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5486 language override: the <a
5487 href="#propdef-font-language-override">font-language-override</a> property</h3>
5489 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5490 <tbody>
5491 <tr>
5492 <td>Name:
5494 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5496 <tr>
5497 <td>Value:
5499 <td><a href="#font-language-override-normal-value"
5500 title="normal!!font-language-override">normal</a> | <a
5501 href="#font-language-override-string-value"><var><string></var></a>
5503 <tr>
5504 <td>Initial:
5506 <td><a href="#font-language-override-normal-value"
5507 title="normal!!font-language-override">normal</a>
5509 <tr>
5510 <td>Applies to:
5512 <td>all elements
5514 <tr>
5515 <td>Inherited:
5517 <td>yes
5519 <tr>
5520 <td>Percentages:
5522 <td>N/A
5524 <tr>
5525 <td>Media:
5527 <td>visual
5529 <tr>
5530 <td>Computed value:
5532 <td>as specified
5534 <tr>
5535 <td>Animatable:
5537 <td>no
5538 </table>
5540 <p>Normally, authors can control the use of language-specific glyph
5541 substitutions and positioning by setting the content language of an
5542 element, as <a href="#language-specific-support">described above</a>:
5544 <pre><!-- Display text using S'gaw Karen specific features -->
5545 <p lang="ksw">...</p></pre>
5547 <p>In some cases, authors may need to specify a language system that
5548 differs from the content language, for example due to the need to mimic
5549 another language's typographic traditions. The ‘<a
5550 href="#propdef-font-language-override"><code
5551 class=property>font-language-override</code></a>’ property allows
5552 authors to explicitly specify the language system of the font, overriding
5553 the language system implied by the content language.
5555 <p>Values have the following meanings:
5557 <dl>
5558 <dt><dfn id=font-language-override-normal-value
5559 title="normal!!font-language-override">normal</dfn>
5561 <dd>specifies that when rendering with OpenType fonts, the content
5562 language of the element is used to infer the OpenType language system
5564 <dt><dfn
5565 id=font-language-override-string-value><var><string></var></dfn>
5567 <dd>single three-letter case-sensitive OpenType <a
5568 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5569 system tag</a>, specifies the OpenType language system to be used instead
5570 of the language system implied by the language of the element
5571 </dl>
5572 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5573 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5575 <p>Use of invalid OpenType language system tags must not generate a parse
5576 error but must be ignored when doing glyph selection and placement.
5578 <div class=example>
5579 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5580 Declaration of Human Rights</a> has been translated into a wide variety
5581 of languages. In Turkish, Article 9 of this document might be marked up
5582 as below:</p>
5584 <pre lang=tr><body lang="tr">
5586 <h4>Madde 9</h4>
5587 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5588 </pre>
5590 <p>Here the user agent uses the value of the ‘<code
5591 class=property>lang</code>’ attribute when rendering text and
5592 appropriately renders this text without ‘<code
5593 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5594 href="#propdef-font-language-override"><code
5595 class=property>font-language-override</code></a>’ property.</p>
5597 <p>However, a given font may lack support for a specific language. In this
5598 situation authors may need to use the typographic conventions of a
5599 related language that are supported by that font:</p>
5601 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5603 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5605 <h4>Члeн 9</h4>
5606 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5608 </pre>
5610 <p>The Macedonian text here will be rendered using Serbian typographic
5611 conventions, with the assumption that the font specified supports
5612 Serbian.</p>
5613 </div>
5615 <p><a id=rendering-considerations></a>
5617 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5618 Resolution</h2>
5620 <p>As described in the previous section, font features can be enabled in a
5621 variety of ways, either via the use of <a href="#propdef-font-variant"
5622 title="font-variant!!property">‘<code
5623 class=property>font-variant</code>’</a> or <a
5624 href="#propdef-font-feature-settings"
5625 title="font-feature-settings!!property">‘<code
5626 class=property>font-feature-settings</code>’</a> in a style rule or
5627 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5628 The resolution order for the union of these settings is defined below.
5629 Features defined via CSS properties are applied on top of layout engine
5630 default features.
5632 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5634 <p>For OpenType fonts, user agents must enable the default features defined
5635 in the OpenType documentation for a given script and writing mode.
5636 Required ligatures, common ligatures and contextual forms must be enabled
5637 by default (OpenType features: <span class=tag>rlig, liga, clig,
5638 calt</span>), along with localized forms (OpenType feature: <span
5639 class=tag>locl</span>), and features required for proper display of
5640 composed characters and marks (OpenType features: <span class=tag>ccmp,
5641 mark, mkmk</span>). These features must always be enabled, even when the
5642 value of the <a href="#propdef-font-variant"
5643 title="font-variant!!property">‘<code
5644 class=property>font-variant</code>’</a> and <a
5645 href="#propdef-font-feature-settings"
5646 title="font-feature-settings!!property">‘<code
5647 class=property>font-feature-settings</code>’</a> properties is <span
5648 title="normal value">‘<code class=property>normal</code>’</span>.
5649 Individual features are only disabled when explicitly overridden by the
5650 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5651 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5652 href="#no-common-ligatures"><code
5653 class=property>no-common-ligatures</code></a>’. For handling complex
5654 scripts such as <a
5655 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5656 <a
5657 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5658 or <a
5659 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5660 additional features are required. For upright text within vertical text
5661 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5662 must be enabled.
5664 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5666 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5667 feature property settings are resolved in the order below, in ascending
5668 order of precedence. This ordering is used to construct a combined list of
5669 font features that affect a given text run.
5671 <ol>
5672 <li>Font features enabled by default, including features required for a
5673 given script.
5675 <li>If the font is defined via an <a
5676 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5677 features implied by the font-variant descriptor in the <a
5678 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5680 <li>If the font is defined via an <a
5681 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5682 features implied by the font-feature-settings descriptor in the <a
5683 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5685 <li>Font features implied by the value of the <a
5686 href="#propdef-font-variant" title="font-variant!!property">‘<code
5687 class=property>font-variant</code>’</a> property, the related <a
5688 href="#propdef-font-variant" title="font-variant!!property">‘<code
5689 class=property>font-variant</code>’</a> subproperties and any other CSS
5690 property that uses OpenType features (e.g. the ‘<a
5691 href="#propdef-font-kerning"><code
5692 class=property>font-kerning</code></a>’ property).</li>
5693 <!-- other CSS props override 'font-variant' but not 'font-feature-settings' -->
5694 <!-- http://lists.w3.org/Archives/Public/www-style/2013Aug/0110.html -->
5696 <li>Feature settings determined by properties other than <a
5697 href="#propdef-font-variant" title="font-variant!!property">‘<code
5698 class=property>font-variant</code>’</a> or <a
5699 href="#propdef-font-feature-settings"
5700 title="font-feature-settings!!property">‘<code
5701 class=property>font-feature-settings</code>’</a>. For example, setting
5702 a non-default value for the ‘<code
5703 class=property>letter-spacing</code>’ property disables common
5704 ligatures.
5706 <li>Font features implied by the value of <a
5707 href="#propdef-font-feature-settings"
5708 title="font-feature-settings!!property">‘<code
5709 class=property>font-feature-settings</code>’</a> property.
5710 </ol>
5712 <p>This ordering allows authors to set up a general set of defaults for
5713 fonts within their <a
5714 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5715 them with property settings for specific elements. General property
5716 settings override the settings in <a
5717 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5718 font feature settings override <a href="#propdef-font-variant"
5719 title="font-variant!!property">‘<code
5720 class=property>font-variant</code>’</a> property settings.
5722 <p>For situations where the combined list of font feature settings contains
5723 more than one value for the same feature, the last value is used. When a
5724 font lacks support for a given underlying font feature, text is simply
5725 rendered as if that font feature was not enabled; font fallback does not
5726 occur and no attempt is made to synthesize the feature except where
5727 explicitly defined for specific properties.
5729 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5730 precedence examples</h3>
5732 <div class=example>
5733 <p>With the styles below, numbers are rendered proportionally when used
5734 within a paragraph but are shown in tabular form within tables of prices:</p>
5736 <pre>body {
5737 font-variant-numeric: proportional-nums;
5738 }
5740 table.prices td {
5741 font-variant-numeric: tabular-nums;
5742 }
5743 </pre>
5744 </div>
5746 <div class=example>
5747 <p>When the <a href="#descdef-font-variant"
5748 title="font-variant!!descriptor">font-variant</a> descriptor is used
5749 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5750 it only applies to the font defined by that rule.</p>
5752 <pre>@font-face {
5753 font-family: MainText;
5754 src: url(http://example.com/font.woff);
5755 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5756 }
5758 body {
5759 font-family: MainText, Helvetica;
5760 }
5762 table.prices td {
5763 font-variant-numeric: tabular-nums;
5764 }
5765 </pre>
5767 <p>In this case, old-style numerals will be used throughout but only where
5768 the font "MainText" is used. Just as in the previous example, tabular
5769 values will be used in price tables since ‘<a
5770 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5771 appears in a general style rule and its use is mutually exclusive with
5772 ‘<a href="#proportional-nums"><code
5773 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5774 will only be used where MainText is used.</p>
5775 </div>
5777 <div class=example>
5778 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5779 also be used to access font features in locally available fonts via the
5780 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5781 class=property>src</code></a>’ descriptor of the <a
5782 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5784 <pre>@font-face {
5785 font-family: BodyText;
5786 src: local("HiraMaruPro-W4");
5787 font-variant: proportional-width;
5788 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5789 }
5791 body { font-family: BodyText, serif; }
5792 </pre>
5794 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5795 text rendering occurs, Japanese kana will be proportionally spaced and
5796 Latin text will be italicised. Text rendered with the fallback serif font
5797 will use default rendering properties.</p>
5798 </div>
5800 <div class=example>
5801 <p>In the example below, discretionary ligatures are enabled only for a
5802 downloadable font but are disabled within spans of class "special":</p>
5804 <pre>@font-face {
5805 font-family: main;
5806 src: url(fonts/ffmeta.woff) format("woff");
5807 font-variant: discretionary-ligatures;
5808 }
5810 body { font-family: main, Helvetica; }
5811 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5812 </pre>
5814 <p>Suppose one adds a rule using ‘<code
5815 class=property>font-feature-settings</code>’ to enable discretionary
5816 ligatures:</p>
5818 <pre>body { font-family: main, Helvetica; }
5819 span { font-feature-settings: "dlig"; }
5820 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5821 </pre>
5823 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5824 spans of class "special". This is because both the <a
5825 href="#propdef-font-feature-settings"
5826 title="font-feature-settings!!property">‘<code
5827 class=property>font-feature-settings</code>’</a> and ‘<a
5828 href="#propdef-font-variant-ligatures"><code
5829 class=property>font-variant-ligatures</code></a>’ properties apply to
5830 these spans. Although the ‘<code class=css>no-discretionary
5831 ligatures</code>’ setting of ‘<a
5832 href="#propdef-font-variant-ligatures"><code
5833 class=property>font-variant-ligatures</code></a>’ effectively disables
5834 the OpenType <span class=tag>dlig</span> feature, because the <a
5835 href="#propdef-font-feature-settings"
5836 title="font-feature-settings!!property">‘<code
5837 class=property>font-feature-settings</code>’</a> is resolved after
5838 that, the ‘<code class=property>dlig</code>’ value reenables
5839 discretionary ligatures.</p>
5840 </div>
5842 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5844 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5845 and <a
5846 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5847 rules can be accessed via the following extensions to the CSS Object
5848 Model.
5850 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5851 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5853 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5854 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5856 <pre class=idl>
5857 interface CSSFontFaceRule : CSSRule {
5858 attribute DOMString family;
5859 attribute DOMString src;
5860 attribute DOMString style;
5861 attribute DOMString weight;
5862 attribute DOMString stretch;
5863 attribute DOMString unicodeRange;
5864 attribute DOMString variant;
5865 attribute DOMString featureSettings;
5866 }</pre>
5868 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5869 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5870 defined a different variant of this rule. This definition supercedes that
5871 one.
5873 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5874 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5875 interface</h3>
5877 <p>The <code>CSSRule</code> interface is extended as follows:
5879 <pre class=idl>partial interface CSSRule {
5880 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5881 }</pre>
5883 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5884 interface represents a <a
5885 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5886 rule.
5888 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5889 attribute DOMString fontFamily;
5890 readonly attribute CSSFontFeatureValuesMap annotation;
5891 readonly attribute CSSFontFeatureValuesMap ornaments;
5892 readonly attribute CSSFontFeatureValuesMap stylistic;
5893 readonly attribute CSSFontFeatureValuesMap swash;
5894 readonly attribute CSSFontFeatureValuesMap characterVariant;
5895 readonly attribute CSSFontFeatureValuesMap styleset;
5896 }
5898 [MapClass(DOMString, sequence<unsigned long>)]
5899 interface CSSFontFeatureValuesMap {
5900 void set(DOMString featureValueName,
5901 (unsigned long or sequence<unsigned long>) values);
5902 }</pre>
5904 <dl class=idl-attributes>
5905 <dt><var>fontFamily</var> of type <code>DOMString</code>
5907 <dd>The list of one or more font families for which a given set of feature
5908 values is defined.
5910 <dt>value maps of type <code>CSSFontFeatureValuesMap</code>, readonly
5912 <dd>Maps of feature values associated with feature value names for a given
5913 ‘<a href="#propdef-font-variant-alternates"><code
5914 class=property>font-variant-alternates</code></a>’ value type
5915 </dl>
5917 <p>Each value map attribute of <a
5918 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5919 reflects the values defined via a corresponding <a
5920 href="#featurevalueblock"><i title="feature_value_block">feature value
5921 block</i></a>. Thus, the <var title="annotation
5922 attribute">annotation</var> attribute contains the values contained within
5923 a <code title="@annotation">@annotation</code> <a
5924 href="#featurevalueblock"><i title="feature_value_block">feature value
5925 block</i></a>, the <var title="ornaments attribute">ornaments</var>
5926 attribute contains the values contained with a <code
5927 title="@ornaments">@ornaments</code> <a href="#featurevalueblock"><i
5928 title="feature_value_block">feature value block</i></a> and so forth.
5930 <p>The <code>CSSFontFeatureValuesMap</code> interface uses the <a
5931 href="http://dev.w3.org/2006/webapi/WebIDL/#es-map-members">default map
5932 class methods</a> but the <code>set</code> method has different behavior.
5933 It takes a sequence of unsigned integers and associates it with a given
5934 <code>featureValueName</code>. The method behaves the same as the default
5935 map class method except that a single unsigned long value is treated as a
5936 sequence of a single value. The method throws an exception if an invalid
5937 number of values is passed in. If the associated <a
5938 href="#featurevalueblock"><i title="feature_value_block">feature value
5939 block</i></a> only allows a limited number of values, the <code>set</code>
5940 method throws an <code>InvalidAccessError</code> exception when the input
5941 sequence to <code>set</code> contains more than the limited number of
5942 values. See the description of <a
5943 href="#multi-valued-feature-value-definitions">multi-valued feature value
5944 definitions</a> for details on the maximum number of values allowed for a
5945 given type of <a href="#featurevalueblock"><i
5946 title="feature_value_block">feature value block</i></a>. The
5947 <code>get</code> method always returns a sequence of values, even if the
5948 sequence only contains a single value.
5950 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5951 properties to CSS properties</h2>
5953 <p><em>This appendix is included as background for some of the problems and
5954 situations that are described in other sections. It should be viewed as
5955 informative only.</em>
5957 <p>Font properties in CSS are designed to be independent of the underlying
5958 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5959 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5960 are facets of the TrueType and OpenType formats that often cause confusion
5961 for authors and present challenges to implementers on different platforms.
5963 <p>Originally developed at Apple, TrueType was designed as an outline font
5964 format for both screen and print. Microsoft joined Apple in developing the
5965 TrueType format and both platforms have supported TrueType fonts since
5966 then. Font data in the TrueType format consists of a set of tables
5967 distinguished with common four-letter tag names, each containing a
5968 specific type of data. For example, naming information, including
5969 copyright and license information, is stored in the ‘<code
5970 class=property>name</code>’ table. The <a
5971 href="#character-map"><em>character map</em></a> (‘<code
5972 class=property>cmap</code>’) table contains a mapping of character
5973 encodings to glyphs. Apple later added additional tables for supporting
5974 enhanced typographic functionality; these are now called Apple Advanced
5975 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5976 tables for advanced typography and called their format OpenType <a
5977 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5979 <p>In many cases the font data used under Microsoft Windows or Linux is
5980 slightly different from the data used under Apple's Mac OS X because the
5981 TrueType format allowed for explicit variation across platforms. This
5982 includes font metrics, names and <a href="#character-map"><em>character
5983 map</em></a> data.
5985 <p>Specifically, font family name data is handled differently across
5986 platforms. For TrueType and OpenType fonts these names are contained in
5987 the ‘<code class=property>name</code>’ table, in name records with
5988 name ID 1. Mulitple names can be stored for different locales, but
5989 Microsoft recommends fonts always include at least a US English version of
5990 the name. On Windows, Microsoft made the decision for backwards
5991 compatibility to limit this family name to a maximum of four faces; for
5992 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5993 ID 21) can be used. Other platforms such as OSX don't have this
5994 limitation, so the family name is used to define all possible groupings.
5996 <p>Other name table data provides names used to uniquely identify a
5997 specific face within a family. The full font name (name ID 4) and the
5998 Postscript name (name ID 6) describe a single face uniquely. For example,
5999 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
6000 and a Postscript name of "GillSans-Bold". There can be multiple localized
6001 versions of the fullname for a given face, but the Postscript name is
6002 always a unique name made from a limited set of ASCII characters.
6004 <p>On various platforms, different names are used to search for a font. For
6005 example, with the Windows GDI CreateIndirectFont API, either a family or
6006 fullname can be used to lookup a face, while on Mac OS X the
6007 CTFontCreateWithName API call is used to lookup a given face using the
6008 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
6009 to be searched using any of these names. In situations where platform
6010 API's automatically substitute other font choices, it may be necessary to
6011 verify a returned font matches a given name.
6013 <p>The weight of a given face can be determined via the usWeightClass field
6014 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
6015 the width can be determined via the usWidthClass of the OS/2 table or
6016 inferred from the style name. For historical reasons related to synthetic
6017 bolding at weights 200 or lower with the Windows GDI API, font designers
6018 have sometimes skewed values in the OS/2 table to avoid these weights.
6020 <p>Rendering complex scripts that use contextual shaping such as Thai,
6021 Arabic and Devanagari requires features present only in OpenType or AAT
6022 fonts. Currently, complex script rendering is supported on Windows and
6023 Linux using OpenType font features while both OpenType and AAT font
6024 features are used under Mac OS X.
6026 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
6028 <h3 class=no-num id=recent-changes> Changes from the <a
6029 href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">July 2013 CSS3
6030 Fonts Last Call Working Draft</a></h3>
6032 <ul>
6033 <li>reorder feature precedence such that features implied by other CSS
6034 properties override ‘<code class=property>font-variant</code>’
6035 settings
6037 <li>switched examples to use .woff files
6039 <li>revised wording of font fetching algorithm
6041 <li>drop ‘<code class=property>auto</code>’ value for ‘<a
6042 href="#propdef-font-size-adjust"><code
6043 class=property>font-size-adjust</code></a>’
6045 <li>clarify effect of ‘<a href="#propdef-font-size-adjust"><code
6046 class=property>font-size-adjust</code></a>’ on <a class=property
6047 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
6048 class=property>line-height</code>’</a>
6050 <li>allow user agents to synthesize OpenType <span class=tag>kern</span>
6051 feature
6053 <li>add example of ordinals and associated markup
6055 <li>minor editorial cleanups
6056 </ul>
6058 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
6060 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
6061 their help and feedback. John Hudson was kind enough to take the time to
6062 explain the subtleties of OpenType language tags and provided the example
6063 of character variant usage for displaying text on Byzantine seals. Ken
6064 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
6065 and Unicode variation selectors. The idea for supporting font features by
6066 using <a href="#propdef-font-variant"
6067 title="font-variant!!property">‘<code
6068 class=property>font-variant</code>’</a> subproperties originated with
6069 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
6070 of the initial design ideas for the <a
6071 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
6072 rule. Thanks also to House Industries for allowing the use of Ed Interlock
6073 in the discretionary ligatures example.
6075 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
6076 that is <em>The Elements of Typographic Style</em>.
6078 <h2 class=no-num id=conformance> Conformance</h2>
6080 <h3 class=no-num id=conventions> Document Conventions</h3>
6082 <p>Conformance requirements are expressed with a combination of descriptive
6083 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
6084 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
6085 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
6086 normative parts of this document are to be interpreted as described in RFC
6087 2119. However, for readability, these words do not appear in all uppercase
6088 letters in this specification.
6090 <p>All of the text of this specification is normative except sections
6091 explicitly marked as non-normative, examples, and notes. <a
6092 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
6094 <p>Examples in this specification are introduced with the words “for
6095 example” or are set apart from the normative text with
6096 <code>class="example"</code>, like this:
6098 <div class=example>
6099 <p>This is an example of an informative example.
6100 </div>
6102 <p>Informative notes begin with the word “Note” and are set apart from
6103 the normative text with <code>class="note"</code>, like this:
6105 <p class=note>Note, this is an informative note.
6107 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
6109 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
6110 classes:
6112 <dl>
6113 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
6114 sheet</dfn>
6116 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
6117 style sheet</a>.
6119 <dt><dfn id=renderer>renderer</dfn>
6121 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
6122 that interprets the semantics of a style sheet and renders documents that
6123 use them.
6125 <dt><dfn id=authoring-tool>authoring tool</dfn>
6127 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
6128 that writes a style sheet.
6129 </dl>
6131 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
6132 declarations that use properties defined in this module have values that
6133 are valid according to the generic CSS grammar and the individual grammars
6134 of each property as given in this module.
6136 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
6137 interpreting the style sheet as defined by the appropriate specifications,
6138 it supports all the features defined by CSS Fonts Level 3 Module by
6139 parsing them correctly and rendering the document accordingly. However,
6140 the inability of a UA to correctly render a document due to limitations of
6141 the device does not make the UA non-conformant. (For example, a UA is not
6142 required to render color on a monochrome monitor.)
6144 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
6145 style sheets that are syntactically correct according to the generic CSS
6146 grammar and the individual grammars of each feature in this module, and
6147 meet all other conformance requirements of style sheets as described in
6148 this module.
6150 <h3 class=no-num id=partial> Partial Implementations</h3>
6152 <p>So that authors can exploit the forward-compatible parsing rules to
6153 assign fallback values, CSS renderers <strong>must</strong> treat as
6154 invalid (and <a
6155 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
6156 appropriate</a>) any at-rules, properties, property values, keywords, and
6157 other syntactic constructs for which they have no usable level of support.
6158 In particular, user agents <strong>must not</strong> selectively ignore
6159 unsupported component values and honor supported values in a single
6160 multi-value property declaration: if any value is considered invalid (as
6161 unsupported values must be), CSS requires that the entire declaration be
6162 ignored.
6164 <h3 class=no-num id=experimental> Experimental Implementations</h3>
6166 <p>To avoid clashes with future CSS features, the CSS2.1 specification
6167 reserves a <a
6168 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
6169 syntax</a> for proprietary and experimental extensions to CSS.
6171 <p>Prior to a specification reaching the Candidate Recommendation stage in
6172 the W3C process, all implementations of a CSS feature are considered
6173 experimental. The CSS Working Group recommends that implementations use a
6174 vendor-prefixed syntax for such features, including those in W3C Working
6175 Drafts. This avoids incompatibilities with future changes in the draft.
6177 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
6179 <p>Once a specification reaches the Candidate Recommendation stage,
6180 non-experimental implementations are possible, and implementors should
6181 release an unprefixed implementation of any CR-level feature they can
6182 demonstrate to be correctly implemented according to spec.
6184 <p>To establish and maintain the interoperability of CSS across
6185 implementations, the CSS Working Group requests that non-experimental CSS
6186 renderers submit an implementation report (and, if necessary, the
6187 testcases used for that implementation report) to the W3C before releasing
6188 an unprefixed implementation of any CSS features. Testcases submitted to
6189 W3C are subject to review and correction by the CSS Working Group.
6191 <p>Further information on submitting testcases and implementation reports
6192 can be found from on the CSS Working Group's website at <a
6193 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
6194 Questions should be directed to the <a
6195 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
6196 mailing list.
6198 <h3 class=no-num id=cr-exit-criteria>CR Exit Criteria</h3>
6200 <p class=replaceme>Remove this section unless/until the module is in CR.</p>
6201 <!-- This text was <a href="http://www.w3.org/Style/CSS/Tracker/actions/44"> decided on 2008-06-04.</a> -->
6203 <p> For this specification to be advanced to Proposed Recommendation, there
6204 must be at least two independent, interoperable implementations of each
6205 feature. Each feature may be implemented by a different set of products,
6206 there is no requirement that all features be implemented by a single
6207 product. For the purposes of this criterion, we define the following
6208 terms:
6210 <dl>
6211 <dt>independent
6213 <dd>each implementation must be developed by a different party and cannot
6214 share, reuse, or derive from code used by another qualifying
6215 implementation. Sections of code that have no bearing on the
6216 implementation of this specification are exempt from this requirement.
6218 <dt>interoperable
6220 <dd>passing the respective test case(s) in the official CSS test suite,
6221 or, if the implementation is not a Web browser, an equivalent test. Every
6222 relevant test in the test suite should have an equivalent test created if
6223 such a user agent (UA) is to be used to claim interoperability. In
6224 addition if such a UA is to be used to claim interoperability, then there
6225 must one or more additional UAs which can also pass those equivalent
6226 tests in the same way for the purpose of interoperability. The equivalent
6227 tests must be made publicly available for the purposes of peer review.
6229 <dt>implementation
6231 <dd>a user agent which:
6232 <ol class=inline>
6233 <li>implements the specification.
6235 <li>is available to the general public. The implementation may be a
6236 shipping product or other publicly available version (i.e., beta
6237 version, preview release, or “nightly build”). Non-shipping product
6238 releases must have implemented the feature(s) for a period of at least
6239 one month in order to demonstrate stability.
6241 <li>is not experimental (i.e., a version specifically designed to pass
6242 the test suite and is not intended for normal usage going forward).
6243 </ol>
6244 </dl>
6246 <p>The specification will remain Candidate Recommendation for at least six
6247 months.
6249 <h2 class=no-num id=references>References</h2>
6251 <h3 class=no-num id=normative-references>Normative References</h3>
6252 <!--begin-normative-->
6253 <!-- Sorted by label -->
6255 <dl class=bibliography>
6256 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6257 <!---->
6259 <dt id=ref-CHARMOD>[CHARMOD]
6261 <dd>Martin J. Dürst; et al. <a
6262 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6263 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6264 2005. W3C Recommendation. URL: <a
6265 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6266 </dd>
6267 <!---->
6269 <dt id=ref-CORS>[CORS]
6271 <dd>Anne van Kesteren. <a
6272 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6273 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6274 Recommendation. (Work in progress.) URL: <a
6275 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6276 </dd>
6277 <!---->
6279 <dt id=ref-CSS21>[CSS21]
6281 <dd>Bert Bos; et al. <a
6282 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6283 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6284 2011. W3C Recommendation. URL: <a
6285 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6286 </dd>
6287 <!---->
6289 <dt id=ref-CSS3VAL>[CSS3VAL]
6291 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6292 href="http://www.w3.org/TR/2013/CR-css3-values-20130730/"><cite>CSS
6293 Values and Units Module Level 3.</cite></a> 30 July 2013. W3C Candidate
6294 Recommendation. (Work in progress.) URL: <a
6295 href="http://www.w3.org/TR/2013/CR-css3-values-20130730/">http://www.w3.org/TR/2013/CR-css3-values-20130730/</a>
6296 </dd>
6297 <!---->
6299 <dt id=ref-HTML5>[HTML5]
6301 <dd>Robin Berjon; et al. <a
6302 href="http://www.w3.org/TR/2013/CR-html5-20130806/"><cite>HTML5.</cite></a>
6303 6 August 2013. W3C Candidate Recommendation. (Work in progress.) URL: <a
6304 href="http://www.w3.org/TR/2013/CR-html5-20130806/">http://www.w3.org/TR/2013/CR-html5-20130806/</a>
6305 </dd>
6306 <!---->
6308 <dt id=ref-OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6310 <dd><a
6311 href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136"><cite>Information
6312 technology — Coding of audio-visual objects — Part 22: Open Font
6313 Format.</cite></a> International Organization for Standardization.
6314 ISO/IEC 14496-22:2009. URL: <a
6315 href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136">http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136</a>
6316 </dd>
6317 <!---->
6319 <dt id=ref-OPENTYPE>[OPENTYPE]
6321 <dd><a
6322 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6323 specification.</cite></a> Microsoft. URL: <a
6324 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6325 </dd>
6326 <!---->
6328 <dt id=ref-OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6330 <dd><a
6331 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6332 feature registry.</cite></a> Microsoft. URL: <a
6333 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6334 </dd>
6335 <!---->
6337 <dt id=ref-RFC2119>[RFC2119]
6339 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6340 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6341 RFC 2119. URL: <a
6342 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6343 </dd>
6344 <!---->
6346 <dt id=ref-UAX15>[UAX15]
6348 <dd>Mark Davis; Ken Whistler. <a
6349 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6350 Forms.</cite></a> 20 September 2013. Unicode Standard Annex #15. URL: <a
6351 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6352 </dd>
6353 <!---->
6355 <dt id=ref-UAX29>[UAX29]
6357 <dd>Mark Davis. <a
6358 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6359 Segmentation.</cite></a> 20 September 2013. Unicode Standard Annex #29.
6360 URL: <a
6361 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6362 </dd>
6363 <!---->
6365 <dt id=ref-UNICODE>[UNICODE]
6367 <dd>The Unicode Consortium. <a
6368 href="http://www.unicode.org/standard/versions/enumeratedversions.html"><cite>The
6369 Unicode Standard.</cite></a> 2013. Defined by: The Unicode Standard,
6370 Version 6.3.0, (Mountain View, CA: The Unicode Consortium, 2013. ISBN
6371 978-1-936213-08-5), as updated from time to time by the publication of
6372 new versions URL: <a
6373 href="http://www.unicode.org/standard/versions/enumeratedversions.html">http://www.unicode.org/standard/versions/enumeratedversions.html</a>
6374 </dd>
6375 <!---->
6376 </dl>
6377 <!--end-normative-->
6378 <!--{{!CSS21}}-->
6379 <!--{{!CSS3VAL}}-->
6380 <!--{{!OPENTYPE}}-->
6381 <!--{{!OPENTYPE-FEATURES}}-->
6382 <!--{{!OPEN-FONT-FORMAT}}-->
6383 <!--{{!UNICODE}}-->
6384 <!--{{!UAX15}}-->
6385 <!--{{!UAX29}}-->
6386 <!--{{!CORS}}-->
6387 <!--{{!HTML5}}-->
6388 <!--{{!CHARMOD}}-->
6390 <h3 class=no-num id=other-references>Other References</h3>
6391 <!--begin-informative-->
6392 <!-- Sorted by label -->
6394 <dl class=bibliography>
6395 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6396 <!---->
6398 <dt id=ref-AAT-FEATURES>[AAT-FEATURES]
6400 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6401 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6402 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6403 </dd>
6404 <!---->
6406 <dt id=ref-ARABIC-TYPO>[ARABIC-TYPO]
6408 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6409 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6410 <!---->
6412 <dt id=ref-CHARMOD-NORM>[CHARMOD-NORM]
6414 <dd>François Yergeau; et al. <a
6415 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6416 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6417 W3C Working Draft. (Work in progress.) URL: <a
6418 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6419 </dd>
6420 <!---->
6422 <dt id=ref-CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6424 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6425 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6426 <!---->
6428 <dt id=ref-CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6430 <dd>L. David Baron. <a
6431 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6432 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6433 Recommendation. (Work in progress.) URL: <a
6434 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6435 </dd>
6436 <!---->
6438 <dt id=ref-CSS3TEXT>[CSS3TEXT]
6440 <dd>Elika J. Etemad; Koji Ishii. <a
6441 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6442 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6443 progress.) URL: <a
6444 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6445 </dd>
6446 <!---->
6448 <dt id=ref-DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6450 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6451 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6452 ISBN 0-201-17633-5.</dd>
6453 <!---->
6455 <dt id=ref-DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6457 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6458 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6459 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6460 2000. W3C Recommendation. URL: <a
6461 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a>
6462 </dd>
6463 <!---->
6465 <dt id=ref-ELEMTYPO>[ELEMTYPO]
6467 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6468 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6469 <!---->
6471 <dt id=ref-LANGCULTTYPE>[LANGCULTTYPE]
6473 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6474 ISBN 1-932026-01-0.</dd>
6475 <!---->
6477 <dt id=ref-OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6479 <dd><a
6480 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6481 User Guide.</cite></a> FontShop International. URL: <a
6482 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6483 </dd>
6484 <!---->
6486 <dt id=ref-RASTER-TRAGEDY>[RASTER-TRAGEDY]
6488 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6489 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6490 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6491 <!---->
6493 <dt id=ref-WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6495 <dd>John Hudson. <a
6496 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6497 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6498 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6499 </dd>
6500 <!---->
6501 </dl>
6502 <!--end-informative-->
6503 <!--{{ARABIC-TYPO}}-->
6504 <!--{{CJKV-INFO-PROCESSING}}-->
6505 <!--{{DIGITAL-TYPOGRAPHY}}-->
6506 <!--{{DOM-LEVEL-2-STYLE}}-->
6507 <!--{{ELEMTYPO}}-->
6508 <!--{{LANGCULTTYPE}}-->
6509 <!--{{OPENTYPE-FONT-GUIDE}}-->
6510 <!--{{RASTER-TRAGEDY}}-->
6511 <!--{{WINDOWS-GLYPH-PROC}}-->
6512 <!--{{CHARMOD-NORM}}-->
6513 <!--{{AAT-FEATURES}}-->
6514 <!--{{CSS3-CONDITIONAL}}-->
6515 <!--{{CSS3TEXT}}-->
6517 <h2 class=no-num id=index>Index</h2>
6518 <!--begin-index-->
6520 <ul class=indexlist>
6521 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6522 title="100...900 weight values"><strong>3.2</strong></a>
6524 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6525 title="<absolute-size>"><strong>3.5</strong></a>
6527 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6528 title="<common-lig-values>"><strong>6.4</strong></a>
6530 <li><var><contextual-alt-values></var>, <a
6531 href="#contextual-alt-values"
6532 title="<contextual-alt-values>"><strong>6.4</strong></a>
6534 <li><var><discretionary-lig-values></var>, <a
6535 href="#discretionary-lig-values"
6536 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6538 <li><var><east-asian-variant-values></var>, <a
6539 href="#east-asian-variant-values"
6540 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6542 <li><var><east-asian-width-values></var>, <a
6543 href="#east-asian-width-values"
6544 title="<east-asian-width-values>"><strong>6.10</strong></a>
6546 <li><var><family-name></var>, <a href="#family-name-value"
6547 title="<family-name>"><strong>3.1</strong></a>
6549 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6550 title="<feature-tag-value>"><strong>6.12</strong></a>
6552 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6553 title="<font-face-name>"><strong>4.3</strong></a>
6555 <li><var><font-variant-css21></var>, <a
6556 href="#font-variant-css21-values"
6557 title="<font-variant-css21>"><strong>3.7</strong></a>
6559 <li><var><generic-family></var>, <a href="#generic-family-value"
6560 title="<generic-family>"><strong>3.1</strong></a>
6562 <li><var><historical-lig-values></var>, <a
6563 href="#historical-lig-values"
6564 title="<historical-lig-values>"><strong>6.4</strong></a>
6566 <li><var><length></var>, <a href="#length-size-value"
6567 title="<length>"><strong>3.5</strong></a>
6569 <li><var><number></var>, <a href="#aspect-ratio-value"
6570 title="<number>"><strong>3.6</strong></a>
6572 <li><var><numeric-figure-values></var>, <a
6573 href="#numeric-figure-values"
6574 title="<numeric-figure-values>"><strong>6.7</strong></a>
6576 <li><var><numeric-fraction-values></var>, <a
6577 href="#numeric-fraction-values"
6578 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6580 <li><var><numeric-spacing-values></var>, <a
6581 href="#numeric-spacing-values"
6582 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6584 <li><var><percentage></var>, <a href="#percentage-size-value"
6585 title="<percentage>"><strong>3.5</strong></a>
6587 <li><var><relative-size></var>, <a href="#relative-size-value"
6588 title="<relative-size>"><strong>3.5</strong></a>
6590 <li><var><string></var>, <a
6591 href="#font-language-override-string-value"
6592 title="<string>"><strong>6.13</strong></a>
6594 <li><var><urange></var>, <a href="#urange-value"
6595 title="<urange>"><strong>4.5</strong></a>
6597 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6598 title="@font-face"><strong>4.1</strong></a>
6600 <li><code>@font-feature-values</code>, <a
6601 href="#at-font-feature-values-rule"
6602 title="@font-feature-values"><strong>6.9</strong></a>
6604 <li>all-petite-caps, <a href="#all-petite-caps"
6605 title=all-petite-caps><strong>6.6</strong></a>
6607 <li>all-small-caps, <a href="#all-small-caps"
6608 title=all-small-caps><strong>6.6</strong></a>
6610 <li>annotation, <a href="#annotation"
6611 title=annotation><strong>6.8</strong></a>
6613 <li>aspect value, <a href="#aspect-value0" title="aspect
6614 value"><strong>3.6</strong></a>
6616 <li>authoring tool, <a href="#authoring-tool" title="authoring
6617 tool"><strong>#</strong></a>
6619 <li>auto
6620 <ul>
6621 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6622 font-kerning"><strong>6.3</strong></a>
6623 </ul>
6625 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6627 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6629 <li>character map, <a href="#character-map" title="character
6630 map"><strong>5.2</strong></a>
6632 <li>character-variant, <a href="#character-variant"
6633 title=character-variant><strong>6.8</strong></a>
6635 <li>common-ligatures, <a href="#common-ligatures"
6636 title=common-ligatures><strong>6.4</strong></a>
6638 <li>composite face, <a href="#composite-face" title="composite
6639 face"><strong>5.2</strong></a>
6641 <li>condensed, <a href="#condensed"
6642 title=condensed><strong>3.3</strong></a>
6644 <li>contextual, <a href="#contextual"
6645 title=contextual><strong>6.4</strong></a>
6647 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6648 title=CSSFontFaceRule><strong>8.1</strong></a>
6650 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6651 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6653 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6654 of"><strong>#</strong></a>
6656 <li>default face, <a href="#default-face" title="default
6657 face"><strong>5.2</strong></a>
6659 <li>descriptor_declaration, <a href="#descriptordeclaration"
6660 title="descriptor_declaration"><strong>4.1</strong></a>
6662 <li>diagonal-fractions, <a href="#diagonal-fractions"
6663 title=diagonal-fractions><strong>6.7</strong></a>
6665 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6666 title=discretionary-ligatures><strong>6.4</strong></a>
6668 <li>effective character map, <a href="#effective-character-map"
6669 title="effective character map"><strong>4.5</strong></a>
6671 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6673 <li>extra-condensed, <a href="#extra-condensed"
6674 title=extra-condensed><strong>3.3</strong></a>
6676 <li>extra-expanded, <a href="#extra-expanded"
6677 title=extra-expanded><strong>3.3</strong></a>
6679 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6680 of"><strong>#</strong></a>
6682 <li>feature_type, <a href="#featuretype"
6683 title="feature_type"><strong>6.9.1</strong></a>
6685 <li>feature_value_block, <a href="#featurevalueblock"
6686 title="feature_value_block"><strong>6.9.1</strong></a>
6688 <li>feature_value_definition, <a href="#featurevaluedefinition"
6689 title="feature_value_definition"><strong>6.9.1</strong></a>
6691 <li>first available font, <a href="#first-available-font" title="first
6692 available font"><strong>5.2</strong></a>
6694 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6696 <li>font specific, <a href="#font-specific" title="font
6697 specific"><strong>6.8</strong></a>
6699 <li>font-family
6700 <ul>
6701 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6702 descriptor"><strong>4.2</strong></a>
6704 <li>property, <a href="#propdef-font-family" title="font-family,
6705 property"><strong>3.1</strong></a>
6706 </ul>
6708 <li>font-feature-settings
6709 <ul>
6710 <li>descriptor, <a href="#descdef-font-feature-settings"
6711 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6713 <li>property, <a href="#propdef-font-feature-settings"
6714 title="font-feature-settings, property"><strong>6.12</strong></a>
6715 </ul>
6717 <li>font-kerning, <a href="#propdef-font-kerning"
6718 title=font-kerning><strong>6.3</strong></a>
6720 <li>font-language-override, <a href="#propdef-font-language-override"
6721 title=font-language-override><strong>6.13</strong></a>
6723 <li>font-size, <a href="#propdef-font-size"
6724 title=font-size><strong>3.5</strong></a>
6726 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6727 title=font-size-adjust><strong>3.6</strong></a>
6729 <li>font-stretch
6730 <ul>
6731 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6732 descriptor"><strong>4.4</strong></a>
6734 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6735 property"><strong>3.3</strong></a>
6736 </ul>
6738 <li>font-style
6739 <ul>
6740 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6741 descriptor"><strong>4.4</strong></a>
6743 <li>property, <a href="#propdef-font-style" title="font-style,
6744 property"><strong>3.4</strong></a>
6745 </ul>
6747 <li>font-synthesis, <a href="#propdef-font-synthesis"
6748 title=font-synthesis><strong>3.8</strong></a>
6750 <li>font-variant
6751 <ul>
6752 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6753 descriptor"><strong>4.7</strong></a>
6755 <li>property, <a href="#propdef-font-variant" title="font-variant,
6756 property"><strong>6.11</strong></a>
6757 </ul>
6759 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6760 title=font-variant-alternates><strong>6.8</strong></a>
6762 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6763 title=font-variant-caps><strong>6.6</strong></a>
6765 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6766 title=font-variant-east-asian><strong>6.10</strong></a>
6768 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6769 title=font-variant-ligatures><strong>6.4</strong></a>
6771 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6772 title=font-variant-numeric><strong>6.7</strong></a>
6774 <li>font-variant-position, <a href="#propdef-font-variant-position"
6775 title=font-variant-position><strong>6.5</strong></a>
6777 <li>font-weight
6778 <ul>
6779 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6780 descriptor"><strong>4.4</strong></a>
6782 <li>property, <a href="#propdef-font-weight" title="font-weight,
6783 property"><strong>3.2</strong></a>
6784 </ul>
6786 <li>font_face_rule, <a href="#fontfacerule"
6787 title="font_face_rule"><strong>4.1</strong></a>
6789 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6790 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6792 <li>font_family_name, <a href="#fontfamilyname"
6793 title="font_family_name"><strong>6.9.1</strong></a>
6795 <li>font_family_name_list, <a href="#fontfamilynamelist"
6796 title="font_family_name_list"><strong>6.9.1</strong></a>
6798 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6799 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6801 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6802 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6804 <li>full-width, <a href="#full-width"
6805 title=full-width><strong>6.10</strong></a>
6807 <li>historical-forms, <a href="#historical-forms"
6808 title=historical-forms><strong>6.8</strong></a>
6810 <li>historical-ligatures, <a href="#historical-ligatures"
6811 title=historical-ligatures><strong>6.4</strong></a>
6813 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6815 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6817 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6819 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6821 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6823 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6825 <li>lining-nums, <a href="#lining-nums"
6826 title=lining-nums><strong>6.7</strong></a>
6828 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6829 definition of"><strong>#</strong></a>
6831 <li>no-common-ligatures, <a href="#no-common-ligatures"
6832 title=no-common-ligatures><strong>6.4</strong></a>
6834 <li>no-contextual, <a href="#no-contextual"
6835 title=no-contextual><strong>6.4</strong></a>
6837 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6838 title=no-discretionary-ligatures><strong>6.4</strong></a>
6840 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6841 title=no-historical-ligatures><strong>6.4</strong></a>
6843 <li>none
6844 <ul>
6845 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6846 font-kerning"><strong>6.3</strong></a>
6848 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6849 title="none, font-size-adjust"><strong>3.6</strong></a>
6851 <li>font-variant, <a href="#font-variant-none-value" title="none,
6852 font-variant"><strong>6.11</strong></a>
6854 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6855 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6856 </ul>
6858 <li>normal
6859 <ul>
6860 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6861 title="normal, font-feature-settings"><strong>6.12</strong></a>
6863 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6864 font-kerning"><strong>6.3</strong></a>
6866 <li>font-language-override, <a
6867 href="#font-language-override-normal-value" title="normal,
6868 font-language-override"><strong>6.13</strong></a>
6870 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6871 font-stretch"><strong>3.3</strong></a>
6873 <li>font-style, <a href="#font-style-normal-value" title="normal,
6874 font-style"><strong>3.4</strong></a>
6876 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6877 font-variant"><strong>6.11</strong></a>
6879 <li>font-variant-alternates, <a
6880 href="#font-variant-alternates-normal-value" title="normal,
6881 font-variant-alternates"><strong>6.8</strong></a>
6883 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6884 title="normal, font-variant-caps"><strong>6.6</strong></a>
6886 <li>font-variant-east-asian, <a
6887 href="#font-variant-east-asian-normal-value" title="normal,
6888 font-variant-east-asian"><strong>6.10</strong></a>
6890 <li>font-variant-ligatures, <a
6891 href="#font-variant-ligatures-normal-value" title="normal,
6892 font-variant-ligatures"><strong>6.4</strong></a>
6894 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6895 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6897 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6898 title="normal, font-variant-position"><strong>6.5</strong></a>
6900 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6901 font-weight"><strong>3.2</strong></a>
6902 </ul>
6904 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6906 <li>oldstyle-nums, <a href="#oldstyle-nums"
6907 title=oldstyle-nums><strong>6.7</strong></a>
6909 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6911 <li>ornaments, <a href="#ornaments"
6912 title=ornaments><strong>6.8</strong></a>
6914 <li>petite-caps, <a href="#petite-caps"
6915 title=petite-caps><strong>6.6</strong></a>
6917 <li>proportional-nums, <a href="#proportional-nums"
6918 title=proportional-nums><strong>6.7</strong></a>
6920 <li>proportional-width, <a href="#proportional-width"
6921 title=proportional-width><strong>6.10</strong></a>
6923 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6925 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6927 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6928 definition of"><strong>#</strong></a>
6930 <li>semi-condensed, <a href="#semi-condensed-"
6931 title=semi-condensed><strong>3.3</strong></a>
6933 <li>semi-expanded, <a href="#semi-expanded"
6934 title=semi-expanded><strong>3.3</strong></a>
6936 <li>serif, definition of, <a href="#serif0" title="serif, definition
6937 of"><strong>#</strong></a>
6939 <li>simplified, <a href="#simplified"
6940 title=simplified><strong>6.10</strong></a>
6942 <li>slashed-zero, <a href="#slashed-zero"
6943 title=slashed-zero><strong>6.7</strong></a>
6945 <li>small-caps, <a href="#small-caps"
6946 title=small-caps><strong>6.6</strong></a>
6948 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6950 <li>stacked-fractions, <a href="#stacked-fractions"
6951 title=stacked-fractions><strong>6.7</strong></a>
6953 <li>style sheet
6954 <ul>
6955 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6956 conformance class"><strong>#</strong></a>
6957 </ul>
6959 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6961 <li>stylistic, <a href="#stylistic"
6962 title=stylistic><strong>6.8</strong></a>
6964 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6966 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6968 <li>support, <a href="#support" title=support><strong>5.2</strong></a>
6970 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6972 <li>system font fallback, <a href="#system-font-fallback" title="system
6973 font fallback"><strong>5.2</strong></a>
6975 <li>tabular-nums, <a href="#tabular-nums"
6976 title=tabular-nums><strong>6.7</strong></a>
6978 <li>titling-caps, <a href="#titling-caps"
6979 title=titling-caps><strong>6.6</strong></a>
6981 <li>traditional, <a href="#traditional"
6982 title=traditional><strong>6.10</strong></a>
6984 <li>ultra-condensed, <a href="#ultra-condensed"
6985 title=ultra-condensed><strong>3.3</strong></a>
6987 <li>ultra-expanded, <a href="#ultra-expanded"
6988 title=ultra-expanded><strong>3.3</strong></a>
6990 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6992 <li>unicode-range, <a href="#descdef-unicode-range"
6993 title=unicode-range><strong>4.5</strong></a>
6995 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6997 <li>width, <a href="#width" title=width><strong>2</strong></a>
6998 </ul>
6999 <!--end-index-->
7001 <h2 class=no-num id=property-index>Property index</h2>
7002 <!--begin-properties-->
7004 <table class=proptable>
7005 <thead>
7006 <tr>
7007 <th>Property
7009 <th>Values
7011 <th>Initial
7013 <th>Applies to
7015 <th>Inh.
7017 <th>Percentages
7019 <th>Media
7021 <tbody>
7022 <tr>
7023 <th><a class=property href="#propdef-font">font</a>
7025 <td>[ [ <‘font-style’> || <font-variant-css21> ||
7026 <‘font-weight’> || <‘font-stretch’ ]?
7027 <‘font-size’> [ / <‘line-height’> ]?
7028 <‘font-family’> ] | caption | icon | menu | message-box |
7029 small-caption | status-bar
7031 <td>see individual properties
7033 <td>all elements
7035 <td>yes
7037 <td>see individual properties
7039 <td>visual
7041 <tr>
7042 <th><span class=property>font-family</span>
7044 <td>[ <family-name> | <generic-family> ] #
7046 <td>depends on user agent
7048 <td>all elements
7050 <td>yes
7052 <td>N/A
7054 <td>visual
7056 <tr>
7057 <th><span class=property>font-feature-settings</span>
7059 <td>normal | <feature-tag-value> #
7061 <td>normal
7063 <td>all elements
7065 <td>yes
7067 <td>N/A
7069 <td>visual
7071 <tr>
7072 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
7074 <td>auto | normal | none
7076 <td>auto
7078 <td>all elements
7080 <td>yes
7082 <td>N/A
7084 <td>visual
7086 <tr>
7087 <th><a class=property
7088 href="#propdef-font-language-override">font-language-override</a>
7090 <td>normal | <string>
7092 <td>normal
7094 <td>all elements
7096 <td>yes
7098 <td>N/A
7100 <td>visual
7102 <tr>
7103 <th><a class=property href="#propdef-font-size">font-size</a>
7105 <td><absolute-size> | <relative-size> | <length> |
7106 <percentage>
7108 <td>medium
7110 <td>all elements
7112 <td>yes
7114 <td>refer to parent element's font size
7116 <td>visual
7118 <tr>
7119 <th><a class=property
7120 href="#propdef-font-size-adjust">font-size-adjust</a>
7122 <td>none | <number>
7124 <td>none
7126 <td>all elements
7128 <td>yes
7130 <td>N/A
7132 <td>visual
7134 <tr>
7135 <th><span class=property>font-stretch</span>
7137 <td>normal | ultra-condensed | extra-condensed | condensed |
7138 semi-condensed | semi-expanded | expanded | extra-expanded |
7139 ultra-expanded
7141 <td>normal
7143 <td>all elements
7145 <td>yes
7147 <td>N/A
7149 <td>visual
7151 <tr>
7152 <th><span class=property>font-style</span>
7154 <td>normal | italic | oblique
7156 <td>normal
7158 <td>all elements
7160 <td>yes
7162 <td>N/A
7164 <td>visual
7166 <tr>
7167 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
7169 <td>none | [ weight || style ]
7171 <td>weight style
7173 <td>all elements
7175 <td>yes
7177 <td>N/A
7179 <td>visual
7181 <tr>
7182 <th><span class=property>font-variant</span>
7184 <td>normal | none | [ <common-lig-values> ||
7185 <discretionary-lig-values> || <historical-lig-values> ||
7186 <contextual-alt-values> || stylistic(<feature-value-name>)
7187 || historical-forms || styleset(<feature-value-name> #) ||
7188 character-variant(<feature-value-name> #) ||
7189 swash(<feature-value-name>) ||
7190 ornaments(<feature-value-name>) ||
7191 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7192 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7193 <numeric-figure-values> || <numeric-spacing-values> ||
7194 <numeric-fraction-values> || ordinal || slashed-zero ||
7195 <east-asian-variant-values> || <east-asian-width-values> ||
7196 ruby ]
7198 <td>normal
7200 <td>all elements
7202 <td>yes
7204 <td>see individual properties
7206 <td>visual
7208 <tr>
7209 <th><a class=property
7210 href="#propdef-font-variant-alternates">font-variant-alternates</a>
7212 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
7213 || styleset(<feature-value-name> #) ||
7214 character-variant(<feature-value-name> #) ||
7215 swash(<feature-value-name>) ||
7216 ornaments(<feature-value-name>) ||
7217 annotation(<feature-value-name>) ]
7219 <td>normal
7221 <td>all elements
7223 <td>yes
7225 <td>N/A
7227 <td>visual
7229 <tr>
7230 <th><a class=property
7231 href="#propdef-font-variant-caps">font-variant-caps</a>
7233 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
7234 | unicase | titling-caps
7236 <td>normal
7238 <td>all elements
7240 <td>yes
7242 <td>N/A
7244 <td>visual
7246 <tr>
7247 <th><a class=property
7248 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
7250 <td>normal | [ <east-asian-variant-values> ||
7251 <east-asian-width-values> || ruby ]
7253 <td>normal
7255 <td>all elements
7257 <td>yes
7259 <td>N/A
7261 <td>visual
7263 <tr>
7264 <th><a class=property
7265 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
7267 <td>normal | none | [ <common-lig-values> ||
7268 <discretionary-lig-values> || <historical-lig-values> ||
7269 <contextual-alt-values> ]
7271 <td>normal
7273 <td>all elements
7275 <td>yes
7277 <td>N/A
7279 <td>visual
7281 <tr>
7282 <th><a class=property
7283 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7285 <td>normal | [ <numeric-figure-values> ||
7286 <numeric-spacing-values> || <numeric-fraction-values> ||
7287 ordinal || slashed-zero ]
7289 <td>normal
7291 <td>all elements
7293 <td>yes
7295 <td>N/A
7297 <td>visual
7299 <tr>
7300 <th><a class=property
7301 href="#propdef-font-variant-position">font-variant-position</a>
7303 <td>normal | sub | super
7305 <td>normal
7307 <td>all elements
7309 <td>yes
7311 <td>N/A
7313 <td>visual
7315 <tr>
7316 <th><span class=property>font-weight</span>
7318 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7319 | 700 | 800 | 900
7321 <td>normal
7323 <td>all elements
7325 <td>yes
7327 <td>N/A
7329 <td>visual
7330 </table>
7331 <!--end-properties-->
7332 <!--begin-descriptors-->
7334 <table class=proptable>
7335 <thead>
7336 <tr>
7337 <th>Descriptor
7339 <th>Value
7341 <th>Initial
7343 <th>Percentages
7345 <th>Media
7347 <tbody>
7348 <tr>
7349 <th><span class=property>font-family</span>
7351 <td><family-name>
7353 <td>N/A
7355 <tr>
7356 <th><span class=property>font-feature-settings</span>
7358 <td>normal | <feature-tag-value> #
7360 <td>normal
7362 <tr>
7363 <th><span class=property>font-stretch</span>
7365 <td>normal | ultra-condensed | extra-condensed | condensed |
7366 semi-condensed | semi-expanded | expanded | extra-expanded |
7367 ultra-expanded
7369 <td>normal
7371 <tr>
7372 <th><span class=property>font-style</span>
7374 <td>normal | italic | oblique
7376 <td>normal
7378 <tr>
7379 <th><span class=property>font-variant</span>
7381 <td>normal | none | [ <common-lig-values> ||
7382 <discretionary-lig-values> || <historical-lig-values> ||
7383 <contextual-alt-values> || stylistic(<feature-value-name>)
7384 || historical-forms || styleset(<feature-value-name> #) ||
7385 character-variant(<feature-value-name> #) ||
7386 swash(<feature-value-name>) ||
7387 ornaments(<feature-value-name>) ||
7388 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7389 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7390 <numeric-figure-values> || <numeric-spacing-values> ||
7391 <numeric-fraction-values> || ordinal || slashed-zero ||
7392 <east-asian-variant-values> || <east-asian-width-values> ||
7393 ruby ]
7395 <td>normal
7397 <tr>
7398 <th><span class=property>font-weight</span>
7400 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7402 <td>normal
7404 <tr>
7405 <th><a class=property href="#descdef-src">src</a>
7407 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7409 <td>N/A
7411 <tr>
7412 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7414 <td><urange> #
7416 <td>U+0-10FFFF
7417 </table>
7418 <!--end-descriptors-->
7419 <script type="text/javascript">
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7422 var i, hiresElements = document.getElementsByClassName("hires");
7423 for (i = 0; i < hiresElements.length; i++) {
7424 var h = hiresElements[i];
7425 if (h.tagName != "IMG") continue;
7426 var src = h.getAttribute("src");
7427 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7428 h.src = src2x;
7429 }
7430 }
7431 </script>
7432 </html>
7433 <!-- Keep this comment at the end of the file
7434 Local variables:
7435 mode: sgml
7436 sgml-declaration:"~/SGML/HTML4.decl"
7437 sgml-default-doctype-name:"html"
7438 sgml-minimize-attributes:t
7439 sgml-nofill-elements:("pre" "style" "br")
7440 sgml-live-element-indicator:t
7441 sgml-omittag:nil
7442 sgml-shorttag:nil
7443 sgml-namecase-general:t
7444 sgml-general-insert-case:lower
7445 sgml-always-quote-attributes:t
7446 sgml-indent-step:nil
7447 sgml-indent-data:t
7448 sgml-parent-document:nil
7449 sgml-exposed-tags:nil
7450 sgml-local-catalogs:nil
7451 sgml-local-ecat-files:nil
7452 End:
7453 -->
