css-fonts/Fonts.html@77d3edf17f8c
css-fonts/Fonts.html
Mon, 26 Aug 2013 16:14:56 +0900
- author
- John Daggett <jdaggett@mozilla.com>
- date
- Mon, 26 Aug 2013 16:14:56 +0900
- changeset 8930
- 77d3edf17f8c
- parent 8927
- 9c4ae1da9e9a
- child 8957
- b3ad55a4d7fc
- permissions
- -rw-r--r--
[css3-fonts] revise description of font-size-adjust to prevent confusion
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-august-2013>Editor's Draft
119 26 August 2013</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/2013/ED-css-fonts-3-20130826/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130826/</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>Editor:
167 <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
168 </dl>
169 <!--begin-copyright-->
170 <p class=copyright><a
171 href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
172 rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
173 title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
174 href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
175 Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
176 title="European Research Consortium for Informatics and
177 Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
178 <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
179 <a
180 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
181 <a
182 href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
183 and <a
184 href="http://www.w3.org/Consortium/Legal/copyright-documents">document
185 use</a> rules apply.</p>
186 <!--end-copyright-->
187 <hr title="Separator for header">
188 </div>
190 <h2 class="no-num no-toc" id=abstract>Abstract</h2>
192 <p>This CSS3 module describes how font properties are specified and how
193 font resources are loaded dynamically. The contents of this specification
194 are a consolidation of content previously divided into <a
195 href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
196 and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
197 Web Fonts</a> modules. The description of font load events was moved into
198 the <a href="http://dev.w3.org/csswg/css-font-load-events/">CSS3 Font Load
199 Events</a> module.
201 <h2 class="no-num no-toc" id=status>Status of this document</h2>
202 <!--begin-status-->
204 <p>This is a public copy of the editors' draft. It is provided for
205 discussion only and may change at any moment. Its publication here does
206 not imply endorsement of its contents by W3C. Don't cite this document
207 other than as work in progress.
209 <p>The (<a
210 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
211 mailing list <a
212 href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
213 www-style@w3.org</a> (see <a
214 href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
215 discussion of this specification. When sending e-mail, please put the text
216 “css3-fonts” in the subject, preferably like this:
217 “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
219 <p>This document was produced by the <a
220 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
221 the <a href="http://www.w3.org/Style/">Style Activity</a>).
223 <p>This document was produced by a group operating under the <a
224 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
225 2004 W3C Patent Policy</a>. W3C maintains a <a
226 href="http://www.w3.org/2004/01/pp-impl/32061/status"
227 rel=disclosure>public list of any patent disclosures</a> made in
228 connection with the deliverables of the group; that page also includes
229 instructions for disclosing a patent. An individual who has actual
230 knowledge of a patent which the individual believes contains <a
231 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
232 Claim(s)</a> must disclose the information in accordance with <a
233 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
234 6 of the W3C Patent Policy</a>.</p>
235 <!--end-status-->
237 <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
239 <p>The following features are at risk and may be removed when exiting CR:
241 <ul>
242 <li>fallback handling for text decoration in superscript/subscript variant
243 glyphs (‘<a href="#propdef-font-variant-position"><code
244 class=property>font-variant-position</code></a>’)
246 <li>‘<a href="#propdef-font-language-override"><code
247 class=property>font-language-override</code></a>’ property
248 </ul>
249 <!--
250 <p>This draft is a <strong>Last Call Working Draft</strong>.
251 Please send comments to the
252 <a href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing list</a>
253 as described above. The <strong>deadline for comments</strong>
254 is six weeks after the date of publication in the header, 22 August 2013.</p>
255 -->
257 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
258 <!--begin-toc-->
260 <ul class=toc>
261 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
263 <li><a href="#typography-background"><span class=secno>2 </span>Typography
264 Background</a>
266 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
267 Properties</a>
268 <ul class=toc>
269 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
270 family: the font-family property</a>
271 <ul class=toc>
272 <li><a href="#generic-font-families"><span class=secno>3.1.1
273 </span>Generic font families</a>
274 </ul>
276 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
277 weight: the font-weight property</a>
279 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
280 width: the font-stretch property</a>
282 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
283 the font-style property</a>
285 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
286 the font-size property</a>
288 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
289 </span>Relative sizing: the font-size-adjust property</a>
291 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
292 property: the font property</a>
294 <li><a href="#font-synthesis-prop"><span class=secno>3.8
295 </span>Controlling synthetic faces: the font-synthesis property</a>
296 </ul>
298 <li><a href="#font-resources"><span class=secno>4 </span>Font
299 Resources</a>
300 <ul class=toc>
301 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
302 <code>@font-face</code> rule</a>
304 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
305 family: the font-family descriptor</a>
307 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
308 src descriptor</a>
310 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
311 descriptors: the font-style, font-weight, font-stretch descriptors</a>
313 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
314 range: the unicode-range descriptor</a>
316 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
317 character ranges to define composite fonts</a>
319 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
320 features: the font-variant and font-feature-settings descriptors</a>
322 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
323 loading guidelines</a>
325 <li><a href="#font-fetching-requirements"><span class=secno>4.9
326 </span>Font fetching requirements</a>
327 </ul>
329 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
330 Matching Algorithm</a>
331 <ul class=toc>
332 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
333 sensitivity of font family names</a>
335 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
336 font styles</a>
338 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
339 matching</a>
341 <li><a href="#char-handling-issues"><span class=secno>5.4
342 </span>Character handling issues</a>
344 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
345 matching changes since CSS 2.1</a>
347 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
348 matching examples</a>
349 </ul>
351 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
352 Properties</a>
353 <ul class=toc>
354 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
355 </span>Glyph selection and positioning</a>
357 <li><a href="#language-specific-support"><span class=secno>6.2
358 </span>Language-specific display</a>
360 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
361 the font-kerning property</a>
363 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
364 </span>Ligatures: the font-variant-ligatures property</a>
366 <li><a href="#font-variant-position-prop"><span class=secno>6.5
367 </span>Subscript and superscript forms: the font-variant-position
368 property</a>
370 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
371 </span>Capitalization: the font-variant-caps property</a>
373 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
374 </span>Numerical formatting: the font-variant-numeric property</a>
376 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
377 </span>Alternates and swashes: the font-variant-alternates property</a>
380 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
381 font specific alternates: the <code>@font-feature-values</code>
382 rule</a>
383 <ul class=toc>
384 <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
385 syntax</a>
387 <li><a href="#multi-valued-feature-value-definitions"><span
388 class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
389 </ul>
391 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
392 </span>East Asian text rendering: the font-variant-east-asian
393 property</a>
395 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
396 shorthand for font rendering: the font-variant property</a>
398 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
399 </span>Low-level font feature settings control: the
400 font-feature-settings property</a>
402 <li><a href="#font-language-override-prop"><span class=secno>6.13
403 </span>Font language override: the font-language-override property</a>
404 </ul>
406 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
407 Feature Resolution </a>
408 <ul class=toc>
409 <li><a href="#default-features"><span class=secno>7.1 </span>Default
410 features</a>
412 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
413 precedence</a>
415 <li><a href="#feature-precedence-examples"><span class=secno>7.3
416 </span>Feature precedence examples</a>
417 </ul>
419 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
420 <ul class=toc>
421 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
422 <code>CSSFontFaceRule</code> interface</a>
424 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
425 <code>CSSFontFeatureValuesRule</code> interface</a>
426 </ul>
428 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
429 platform font properties to CSS properties</a>
431 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
432 <ul class=toc>
433 <li class=no-num><a href="#recent-changes"> Changes from the July 2013
434 CSS3 Fonts Last Call Working Draft</a>
435 </ul>
437 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
439 <li class=no-num><a href="#conformance"> Conformance</a>
440 <ul class=toc>
441 <li class=no-num><a href="#conventions"> Document Conventions</a>
443 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
446 <li class=no-num><a href="#partial"> Partial Implementations</a>
448 <li class=no-num><a href="#experimental"> Experimental
449 Implementations</a>
451 <li class=no-num><a href="#testing"> Non-Experimental
452 Implementations</a>
453 </ul>
455 <li class=no-num><a href="#references">References</a>
456 <ul class=toc>
457 <li class=no-num><a href="#normative-references">Normative
458 References</a>
460 <li class=no-num><a href="#other-references">Other References</a>
461 </ul>
463 <li class=no-num><a href="#index">Index</a>
465 <li class=no-num><a href="#property-index">Property index</a>
466 </ul>
467 <!--end-toc-->
469 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
471 <p>A font provides a resource containing the visual representation of
472 characters. At the simplest level it contains information that maps
473 character codes to shapes (called glyphs) that represent these characters.
474 Fonts sharing a common design style are commonly grouped into font
475 families classified by a set of standard font properties. Within a family,
476 the shape displayed for a given character can vary by stroke weight, slant
477 or relative width, among others. An individual font face is described by a
478 unique combination of these properties. For a given range of text, CSS
479 font properties are used to select a font family and a specific font face
480 within that family to be used when rendering that text. As a simple
481 example, to use the bold form of Helvetica one could use:
483 <pre>body {
484 font-family: Helvetica;
485 font-weight: bold;
486 }</pre>
488 <p>Font resources may be installed locally on the system on which a user
489 agent is running or downloadable. For local font resources descriptive
490 information can be obtained directly from the font resource. For
491 downloadable font resources (sometimes referred to as web fonts), the
492 descriptive information is included with the reference to the font
493 resource.
495 <p>Families of fonts typically don't contain a single face for each
496 possible variation of font properties. The CSS font selection mechanism
497 describes how to match a given set of CSS font properties to a single font
498 face.
500 <h2 id=typography-background><span class=secno>2 </span>Typography
501 Background</h2>
503 <p><em>This section is non-normative.</em>
505 <p> Typographic traditions vary across the globe, so there is no unique way
506 to classify all fonts across languages and cultures. For even common Latin
507 letters, wide variations are possible:
509 <div class=figure><img alt="variations in glyphs for a single character"
510 src=aaaaaa.png>
511 <p class=caption>One character, many glyph variations
512 </div>
514 <p>Differences in the anatomy of letterforms is one way to distinguish
515 fonts. For Latin fonts, flourishes at the ends of a character's main
516 strokes, or serifs, can distinguish a font from those without. Similar
517 comparisons exist in non-Latin fonts between fonts with tapered strokes
518 and those using primarily uniform strokes:
520 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
521 <p class=caption>Letterforms with and without serifs
522 </div>
524 <div class=figure><img alt="serif vs. non-serifs for japanese"
525 src=minchovsgothic.png>
526 <p class=caption>Similar groupings for Japanese typefaces
527 </div>
529 <p>Fonts contain letterforms and the data needed to map characters to these
530 letterforms. Often this may be a simple one-to-one mapping, but more
531 complex mappings are also possible. The use of combining diacritic marks
532 creates many variations for an underlying letterform:
534 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
535 <p class=caption>Variations with diacritic marks
536 </div>
538 <p>A sequence of characters can be represented by a single glyph known as a
539 ligature:
541 <div class=figure><img alt="example of a fi ligature"
542 src=final-ligature.png>
543 <p class=caption>Ligature example
544 </div>
546 <p>Visual transformations based on textual context are often stylistic
547 option in European languages. They are required to correctly render
548 languages like Arabic, the lam and alef characters below <em>must</em> be
549 combined when they exist in sequence:
551 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
552 <p class=caption>Required Arabic ligature
553 </div>
555 <p>The relative complexity of these shaping transformations requires
556 additional data within the font.
558 <p>Sets of font faces with various stylistic variations are often grouped
559 together into font families. In the simplest case a regular face is
560 supplemented with bold and italic faces, but much more extensive groupings
561 are possible. Variations in the thickness of letterform strokes, the <dfn
562 id=weight>weight</dfn>, and the overall proportions of the letterform, the
563 <dfn id=width>width</dfn>, are most common. In the example below, each
564 letter uses a different font face within the Univers font family. The
565 width used increases from top to bottom and the weight increases from left
566 to right:
568 <div class=figure><img alt="various width and weight variations within a
569 single family" src=weightwidthvariations.png>
570 <p class=caption>Weight and width variations within a single font family
571 </div>
573 <p>Creating fonts that support multiple scripts is a difficult task;
574 designers need to understand the cultural traditions surrounding the use
575 of type in different scripts and come up with letterforms that somehow
576 share a common theme. Many languages often share a common script and each
577 of these languages may have noticeable stylistic differences. For example,
578 the Arabic script is shared by Persian and Urdu and Cyrillic is used with
579 many languages, not just Russian.
581 <p>The <a href="#character-map"><em>character map</em></a> of a font
582 defines the mapping of characters to glyphs for that font. If a document
583 contains characters not supported by the <a href="#character-map"><em
584 title="character map">character maps</em></a> of the fonts contained in a
585 font family list, a user agent may use a <a
586 href="#system-font-fallback"><em>system font fallback</em></a> procedure
587 to locate an appropriate font that does. If no appropriate font can be
588 found, some form of "missing glyph" character will be rendered by the user
589 agent. System fallback can occur when the specified list of font families
590 does not include a font that supports a given character.
592 <p>Although the <a href="#character-map"><em>character map</em></a> of a
593 font maps a given character to a glyph for that character, modern font
594 technologies such as OpenType and AAT (Apple Advanced Typography) provide
595 ways of mapping a character to different glyphs based upon feature
596 settings. Fonts in these formats allow these features to be embedded in
597 the font itself and controlled by applications. Common typographic
598 features which can be specified this way include ligatures, swashes,
599 contextual alternates, proportional and tabular figures, and automatic
600 fractions, to list just a few. For a visual overview of OpenType features,
601 see the <a href="#OPENTYPE-FONT-GUIDE"
602 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
604 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
606 <p>The particular font face used to render a character is determined by the
607 font family and other font properties that apply to a given element. This
608 structure allows settings to be varied independent of each other.</p>
609 <!-- prop: font-family -->
611 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
612 href="#propdef-font-family">font-family</a> property</h3>
614 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
615 <tbody>
616 <tr>
617 <td>Name:
619 <td><dfn id=propdef-font-family
620 title="font-family!!property">font-family</dfn>
622 <tr>
623 <td>Value:
625 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
626 <a href="#generic-family-value"><var><generic-family></var></a> ]
627 #
629 <tr>
630 <td>Initial:
632 <td>depends on user agent
634 <tr>
635 <td>Applies to:
637 <td>all elements
639 <tr>
640 <td>Inherited:
642 <td>yes
644 <tr>
645 <td>Percentages:
647 <td>N/A
649 <tr>
650 <td>Media:
652 <td>visual
654 <tr>
655 <td>Computed value:
657 <td>as specified
659 <tr>
660 <td>Animatable:
662 <td>no
663 </table>
665 <p>This property specifies a prioritized list of font family names or
666 generic family names. A font family defines a set of faces that vary in
667 weight, width or slope. CSS uses the combination of a family name with
668 other style attributes to select an individual face. Using this selection
669 mechanism, rather than selecting a face via the style name as is often
670 done in design applications, allows some degree of regularity in textual
671 display when fallback occurs.
673 <p class=note>Designers should note that the CSS definition of font
674 attributes used for selection are explicitly not intended to define a font
675 taxonomy. A type designer's idea of a family may often extend to a set of
676 faces that vary along axes other than just the standard axes of weight,
677 width and slope. A family may extend to include both a set of serif faces
678 and a set of sans-serif faces or vary along axes that are unique to that
679 family. The CSS font selection mechanism merely provides a way to
680 determine the “closest” substitute when substitution is necessary.
682 <p>Unlike other CSS properties, component values are a comma-separated list
683 indicating alternatives. A user agent iterates through the list of family
684 names until it matches an available font that contains a glyph for the
685 character to be rendered. This allows for differences in available fonts
686 across platforms and for differences in the range of characters supported
687 by individual fonts.
689 <p>A font family name only specifies a name given to a set of font faces,
690 it does not specify an individual face. For example, given the
691 availability of the fonts below, Futura would match but Futura Medium
692 would not:
694 <div class=figure><img alt="family and face names"
695 src=familyvsfacename.png>
696 <p class=caption>Family and individual face names
697 </div>
699 <p>Consider the example below:
701 <div class=example>
702 <pre>body {
703 font-family: Helvetica, Verdana, sans-serif;
704 }</pre>
706 <p>If Helvetica is available it will be used when rendering. If neither
707 Helvetica nor Verdana is present, then the user-agent-defined sans serif
708 font will be used.</p>
709 </div>
711 <p>There are two types of font family names:
713 <dl>
714 <dt><dfn id=family-name-value><var><family-name></var></dfn>
716 <dd>The name of a font family of choice such as Helvetica or Verdana in
717 the previous example.
719 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
721 <dd> The following generic family keywords are defined: ‘<a
722 href="#serif"><code class=property>serif</code></a>’, ‘<a
723 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
724 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
725 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
726 href="#monospace"><code class=property>monospace</code></a>’. These
727 keywords can be used as a general fallback mechanism when an author's
728 desired font choices are not available. As keywords, they must not be
729 quoted. Authors are encouraged to append a generic font family as a last
730 alternative for improved robustness.
731 </dl>
733 <p>Font family names other than generic families must either be given
734 quoted as <a
735 href="http://www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or
736 unquoted as a sequence of one or more <a
737 href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
738 This means most punctuation characters and digits at the start of each
739 token must be escaped in unquoted font family names.
741 <p>To illustrate this, the following declarations are invalid:
743 <pre>
744 font-family: Red/Black, sans-serif;
745 font-family: "Lucida" Grande, sans-serif;
746 font-family: Ahem!, sans-serif;
747 font-family: test@foo, sans-serif;
748 font-family: #POUND, sans-serif;
749 font-family: Hawaii 5-0, sans-serif;
750 </pre>
752 <p>If a sequence of identifiers is given as a font family name, the
753 computed value is the name converted to a string by joining all the
754 identifiers in the sequence by single spaces.
756 <p>To avoid mistakes in escaping, it is recommended to quote font family
757 names that contain white space, digits, or punctuation characters other
758 than hyphens:
760 <pre>
761 body { font-family: "New Century Schoolbook", serif }
763 <BODY STYLE="font-family: '21st Century', fantasy">
764 </pre>
766 <p>Font family <em>names</em> that happen to be the same as a keyword value
767 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
768 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
769 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
770 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
771 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
772 class=property>cursive</code></a>’) must be quoted to prevent confusion
773 with the keywords with the same names. The keywords ‘<code
774 class=property>initial</code>’ and ‘<code
775 class=property>default</code>’ are reserved for future use and must also
776 be quoted when used as font names. UAs must not consider these keywords as
777 matching the <a
778 href="#family-name-value"><var><family-name></var></a> type.
780 <p>The precise way a set of fonts are grouped into font families varies
781 depending upon the platform font management API's. The Windows GDI API
782 only allows four faces to be grouped into a family while the DirectWrite
783 API and API's on OSX and other platforms support font families with a
784 variety of weights, widths and slopes (see <a
785 href="#platform-props-to-css">Appendix A</a> for more details).
787 <p>Some font formats allow fonts to carry multiple localizations of the
788 family name. User agents must recognize and correctly match all of these
789 names independent of the underlying platform localization, system API used
790 or document encoding:
792 <div class=figure><img alt="examples of localized family names"
793 src=localizedfamilynames.png>
794 <p class=caption>Localized family names
795 </div>
797 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
798 families</h4>
800 <p>All five generic font families are defined to exist in all CSS
801 implementations (they need not necessarily map to five distinct actual
802 fonts). User agents should provide reasonable default choices for the
803 generic font families, which express the characteristics of each family as
804 well as possible within the limits allowed by the underlying technology.
805 User agents are encouraged to allow users to select alternative choices
806 for the generic fonts.
808 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
809 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
811 <p>Serif fonts represent the formal text style for a script. This often
812 means but is not limited to glyphs that have finishing strokes, flared or
813 tapering ends, or have actual serifed endings (including slab serifs).
814 Serif fonts are typically proportionately-spaced. They often display a
815 greater variation between thick and thin strokes than fonts from the ‘<a
816 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
817 font family. CSS uses the term ‘<a href="#serif"><code
818 class=property>serif</code></a>’ to apply to a font for any script,
819 although other names may be more familiar for particular scripts, such as
820 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
821 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
822 class=property>serif</code></a>’ more due to its typographic role rather
823 than its actual design style. Any font that is so described may be used to
824 represent the generic ‘<a href="#serif"><code
825 class=property>serif</code></a>’ family.
827 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
828 <p class=caption>Sample serif fonts
829 </div>
831 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
832 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
833 id=sans-serif>sans-serif</dfn></a></span></h5>
835 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
836 low contrast (vertical and horizontal stems have the close to the same
837 thickness) and have stroke endings that are plain -- without any flaring,
838 cross stroke, or other ornamentation. Sans-serif fonts are typically
839 proportionately-spaced. They often have little variation between thick and
840 thin strokes, compared to fonts from the ‘<a href="#serif"><code
841 class=property>serif</code></a>’ family. CSS uses the term ‘<a
842 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
843 to a font for any script, although other names may be more familiar for
844 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
845 (Korean). Any font that is so described may be used to represent the
846 generic ‘<a href="#sans-serif"><code
847 class=property>sans-serif</code></a>’ family.
849 <div class=figure><img alt="sample sans-serif fonts"
850 src=sansserifexamples.png>
851 <p class=caption>Sample sans-serif fonts
852 </div>
854 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
855 title="cursive, definition of"> <a name=cursive-def><dfn
856 id=cursive>cursive</dfn></a></span></h5>
858 <p>Glyphs in cursive fonts generally use a more informal script style, and
859 the result looks more like handwritten pen or brush writing than printed
860 letterwork. CSS uses the term ‘<a href="#cursive"><code
861 class=property>cursive</code></a>’ to apply to a font for any script,
862 although other names such as Chancery, Brush, Swing and Script are also
863 used in font names.
865 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
866 <p class=caption>Sample cursive fonts
867 </div>
869 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
870 title="fantasy, definition of"> <a name=fantasy-def><dfn
871 id=fantasy>fantasy</dfn></a></span></h5>
873 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
874 playful representations of characters. These do not include Pi or Picture
875 fonts which do not represent actual characters.
877 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
878 <p class=caption>Sample fantasy fonts
879 </div>
881 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
882 title="monospace, definition of"> <a name=monospace-def><dfn
883 id=monospace>monospace</dfn></a></span></h5>
885 <p>The sole criterion of a monospace font is that all glyphs have the same
886 fixed width. This is often used to render samples of computer code.
888 <div class=figure><img alt="sample monospace fonts"
889 src=monospaceexamples.png>
890 <p class=caption>Sample monospace fonts
891 </div>
892 <!-- prop: font-weight -->
894 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
895 href="#propdef-font-weight">font-weight</a> property</h3>
897 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
898 <tbody>
899 <tr>
900 <td>Name:
902 <td><dfn id=propdef-font-weight
903 title="font-weight!!property">font-weight</dfn>
905 <tr>
906 <td>Value:
908 <td><a href="#font-weight-normal-value"
909 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
910 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
911 href="#font-weight-numeric-values" title="100...900 weight
912 values">100</a> | <a href="#font-weight-numeric-values"
913 title="100...900 weight values">200</a> | <a
914 href="#font-weight-numeric-values" title="100...900 weight
915 values">300</a> | <a href="#font-weight-numeric-values"
916 title="100...900 weight values">400</a> | <a
917 href="#font-weight-numeric-values" title="100...900 weight
918 values">500</a> | <a href="#font-weight-numeric-values"
919 title="100...900 weight values">600</a> | <a
920 href="#font-weight-numeric-values" title="100...900 weight
921 values">700</a> | <a href="#font-weight-numeric-values"
922 title="100...900 weight values">800</a> | <a
923 href="#font-weight-numeric-values" title="100...900 weight
924 values">900</a>
926 <tr>
927 <td>Initial:
929 <td>normal
931 <tr>
932 <td>Applies to:
934 <td>all elements
936 <tr>
937 <td>Inherited:
939 <td>yes
941 <tr>
942 <td>Percentages:
944 <td>N/A
946 <tr>
947 <td>Media:
949 <td>visual
951 <tr>
952 <td>Computed value:
954 <td>numeric weight value (see description)
956 <tr>
957 <td>Animatable:
959 <td>as <a
960 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
961 weight</a>
962 </table>
964 <p>The <a href="#propdef-font-weight"
965 title="font-weight!!property">‘<code
966 class=property>font-weight</code>’</a> property specifies the weight of
967 glyphs in the font, their degree of blackness or stroke thickness.
969 <p>Values have the following meanings:
971 <dl>
972 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
973 to 900</dfn>
975 <dd>These values form an ordered sequence, where each number indicates a
976 weight that is at least as dark as its predecessor. These roughly
977 correspond to the commonly used weight names below:
978 </dl>
980 <ul>
981 <li>100 - Thin
983 <li>200 - Extra Light (Ultra Light)
985 <li>300 - Light
987 <li>400 - Normal
989 <li>500 - Medium
991 <li>600 - Semi Bold (Demi Bold)
993 <li>700 - Bold
995 <li>800 - Extra Bold (Ultra Bold)
997 <li>900 - Black (Heavy)
998 </ul>
1000 <dl>
1001 <dt><dfn id=font-weight-normal-value
1002 title="normal!!font-weight">normal</dfn>
1004 <dd>Same as ‘<code class=css>400</code>’.
1006 <dt><dfn id=bold>bold</dfn>
1008 <dd>Same as ‘<code class=css>700</code>’.
1010 <dt><dfn id=bolder>bolder</dfn>
1012 <dd>Specifies a bolder weight than the inherited value.
1014 <dt><dfn id=lighter>lighter</dfn>
1016 <dd>Specifies a lighter weight than the inherited value.
1017 </dl>
1019 <p>Font formats that use a scale other than a nine-step scale should map
1020 their scale onto the CSS scale so that 400 roughly corresponds with a face
1021 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1022 face that would be labeled as Bold. Or weights may be inferred from the
1023 style names, ones that correspond roughly with the scale above. The scale
1024 is relative, so a face with a larger weight value must never appear
1025 lighter. If style names are used to infer weights, care should be taken to
1026 handle variations in style names across locales.
1028 <p>Quite often there are only a few weights available for a particular font
1029 family. When a weight is specified for which no face exists, a face with a
1030 nearby weight is used. In general, bold weights map to faces with heavier
1031 weights and light weights map to faces with lighter weights (see the <a
1032 href="#font-matching-algorithm">font matching section below</a> for a
1033 precise definition). The examples here illustrate which face is used for
1034 different weights, grey indicates a face for that weight does not exist so
1035 a face with a nearby weight is used:
1037 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1038 900 weights" src=optimaweights.png>
1039 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1040 weight faces
1041 </div>
1043 <div class=figure><img alt="weight mappings for a family with 300, 600
1044 weights" src=hiraginoweights.png>
1045 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1046 faces
1047 </div>
1049 <p>Although the practice is not well-loved by typographers, bold faces are
1050 often synthesized by user agents for faces that lack actual bold faces.
1051 For the purposes of style matching, these faces must be treated as if they
1052 exist within the family. Authors can explicitly avoid this behavior by
1053 using the ‘<a href="#propdef-font-synthesis"><code
1054 class=property>font-synthesis</code></a>’ property.
1056 <p>Specified values of ‘<a href="#bolder"><code
1057 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1058 class=property>lighter</code></a>’ indicate weights relative to the
1059 weight of the parent element. The computed weight is calculated based on
1060 the inherited <a href="#propdef-font-weight"
1061 title="font-weight!!property">‘<code
1062 class=property>font-weight</code>’</a> value using the chart below.
1064 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1065 <thead>
1066 <tr>
1067 <th>Inherited value
1069 <th>bolder
1071 <th>lighter
1073 <tbody>
1074 <tr>
1075 <th>100
1077 <td>400
1079 <td>100
1081 <tr>
1082 <th>200
1084 <td>400
1086 <td>100
1088 <tr>
1089 <th>300
1091 <td>400
1093 <td>100
1095 <tr>
1096 <th>400
1098 <td>700
1100 <td>100
1102 <tr>
1103 <th>500
1105 <td>700
1107 <td>100
1109 <tr>
1110 <th>600
1112 <td>900
1114 <td>400
1116 <tr>
1117 <th>700
1119 <td>900
1121 <td>400
1123 <tr>
1124 <th>800
1126 <td>900
1128 <td>700
1130 <tr>
1131 <th>900
1133 <td>900
1135 <td>700
1136 </table>
1138 <p>The table above is equivalent to selecting the next relative bolder or
1139 lighter face, given a font family containing normal and bold faces along
1140 with a thin and a heavy face. Authors who desire finer control over the
1141 exact weight values used for a given element may use numerical values
1142 instead of relative weights.</p>
1143 <!-- prop: font-stretch -->
1145 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1146 href="#propdef-font-stretch">font-stretch</a> property</h3>
1148 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1149 <tbody>
1150 <tr>
1151 <td>Name:
1153 <td><dfn id=propdef-font-stretch
1154 title="font-stretch!!property">font-stretch</dfn>
1156 <tr>
1157 <td>Value:
1159 <td> <a href="#font-stretch-normal-value"
1160 title="normal!!font-stretch">normal</a> | <a
1161 href="#ultra-condensed">ultra-condensed</a> | <a
1162 href="#extra-condensed">extra-condensed</a> | <a
1163 href="#condensed">condensed</a> | <a
1164 href="#semi-condensed-">semi-condensed</a> | <a
1165 href="#semi-expanded">semi-expanded</a> | <a
1166 href="#expanded">expanded</a> | <a
1167 href="#extra-expanded">extra-expanded</a> | <a
1168 href="#ultra-expanded">ultra-expanded</a>
1170 <tr>
1171 <td>Initial:
1173 <td>normal
1175 <tr>
1176 <td>Applies to:
1178 <td>all elements
1180 <tr>
1181 <td>Inherited:
1183 <td>yes
1185 <tr>
1186 <td>Percentages:
1188 <td>N/A
1190 <tr>
1191 <td>Media:
1193 <td>visual
1195 <tr>
1196 <td>Computed value:
1198 <td>as specified
1200 <tr>
1201 <td>Animatable:
1203 <td>as <a href="#font-stretch-animation">font stretch</a>
1204 </table>
1206 <p>The <a href="#propdef-font-stretch"
1207 title="font-stretch!!property">‘<code
1208 class=property>font-stretch</code>’</a> property selects a normal,
1209 condensed, or expanded face from a font family. Absolute keyword values
1210 have the following ordering, from narrowest to widest:
1212 <ul>
1213 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1215 <li><dfn id=extra-condensed>extra-condensed</dfn>
1217 <li><dfn id=condensed>condensed</dfn>
1219 <li><dfn id=semi-condensed->semi-condensed </dfn>
1221 <li><dfn id=font-stretch-normal-value
1222 title="normal!!font-stretch">normal</dfn>
1224 <li><dfn id=semi-expanded>semi-expanded</dfn>
1226 <li><dfn id=expanded>expanded</dfn>
1228 <li><dfn id=extra-expanded>extra-expanded</dfn>
1230 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1231 </ul>
1233 <p>When a face does not exist for a given width, normal or condensed values
1234 map to a narrower face, otherwise a wider face. Conversely, expanded
1235 values map to a wider face, otherwise a narrower face. The figure below
1236 shows how the nine font-stretch property settings affect font selection
1237 for font family containing a variety of widths, grey indicates a width for
1238 which no face exists and a different width is substituted:
1240 <div class=figure><img alt="width mappings for a family with condensed,
1241 normal and expanded faces" src=universwidths.png>
1242 <p class=caption>Width mappings for a font family with condensed, normal
1243 and expanded width faces
1244 </div>
1246 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1247 interpolated in discrete steps. The interpolation happens as though the
1248 ordered values are equally spaced real numbers. The interpolation result
1249 is rounded to the nearest value, with values exactly halfway between two
1250 values rounded towards the later value in the list above.</p>
1251 <!-- prop: font-style -->
1253 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1254 href="#propdef-font-style">font-style</a> property</h3>
1256 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1257 <tbody>
1258 <tr>
1259 <td>Name:
1261 <td><dfn id=propdef-font-style
1262 title="font-style!!property">font-style</dfn>
1264 <tr>
1265 <td>Value:
1267 <td><a href="#font-style-normal-value"
1268 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1269 <a href="#oblique">oblique</a>
1271 <tr>
1272 <td>Initial:
1274 <td>normal
1276 <tr>
1277 <td>Applies to:
1279 <td>all elements
1281 <tr>
1282 <td>Inherited:
1284 <td>yes
1286 <tr>
1287 <td>Percentages:
1289 <td>N/A
1291 <tr>
1292 <td>Media:
1294 <td>visual
1296 <tr>
1297 <td>Computed value:
1299 <td>as specified
1301 <tr>
1302 <td>Animatable:
1304 <td>no
1305 </table>
1307 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1308 class=property>font-style</code>’</a> property allows italic or oblique
1309 faces to be selected. Italic forms are generally cursive in nature while
1310 oblique faces are typically sloped versions of the regular face. Oblique
1311 faces can be simulated by artificially sloping the glyphs of the regular
1312 face. Compare the artificially sloped renderings of Palatino ‘<code
1313 class=property>a</code>’ and Baskerville ‘<code
1314 class=property>N</code>’ in grey with the actual italic versions:
1316 <div class=figure><img alt="artificial sloping vs. real italics"
1317 src=realvsfakeitalics.png>
1318 <p class=caption>Artificial sloping versus real italics
1319 </div>
1321 <p>Values have the following meanings:
1323 <dl>
1324 <dt><dfn id=font-style-normal-value
1325 title="normal!!font-style">normal</dfn>
1327 <dd>selects a face that is classified as a normal face, one that is
1328 neither italic or obliqued
1330 <dt><dfn id=italic>italic</dfn>
1332 <dd>selects a font that is labeled as an italic face, or an oblique face
1333 if one is not
1335 <dt><dfn id=oblique>oblique</dfn>
1337 <dd>selects a font that is labeled as an oblique face, or an italic face
1338 if one is not
1339 </dl>
1341 <p>If no italic or oblique face is available, oblique faces can be
1342 synthesized by rendering non-obliqued faces with an artificial obliquing
1343 operation. The use of these artificially obliqued faces can be disabled
1344 using the ‘<a href="#propdef-font-synthesis"><code
1345 class=property>font-synthesis</code></a>’ property. The details of the
1346 obliquing operation are not explicitly defined.</p>
1347 <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
1349 <p>Many scripts lack the tradition of mixing a cursive form within text
1350 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1351 always lack italic or oblique faces. Fonts that support a mixture of
1352 scripts will sometimes omit specific scripts such as Arabic from the set
1353 of glyphs supported in the italic face. User agents should be careful
1354 about making <a href="#character-map"><em>character map</em></a>
1355 assumptions across faces when implementing support for <a
1356 href="#system-font-fallback"><em>system font fallback</em></a>.</p>
1357 <!-- prop: font-size -->
1359 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1360 href="#propdef-font-size">font-size</a> property</h3>
1362 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1363 <tbody>
1364 <tr>
1365 <td>Name:
1367 <td><dfn id=propdef-font-size>font-size</dfn>
1369 <tr>
1370 <td>Value:
1372 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1373 | <a href="#relative-size-value"><var><relative-size></var></a> |
1374 <a href="#length-size-value"><var><length></var></a> | <a
1375 href="#percentage-size-value"><var><percentage></var></a>
1377 <tr>
1378 <td>Initial:
1380 <td>medium
1382 <tr>
1383 <td>Applies to:
1385 <td>all elements
1387 <tr>
1388 <td>Inherited:
1390 <td>yes
1392 <tr>
1393 <td>Percentages:
1395 <td>refer to parent element's font size
1397 <tr>
1398 <td>Media:
1400 <td>visual
1402 <tr>
1403 <td>Computed value:
1405 <td>absolute length
1407 <tr>
1408 <td>Animatable:
1410 <td>as <a
1411 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1412 </table>
1414 <p>This property indicates the desired height of glyphs from the font. For
1415 scalable fonts, the font-size is a scale factor applied to the EM unit of
1416 the font. (Note that certain glyphs may bleed outside their EM box.) For
1417 non-scalable fonts, the font-size is converted into absolute units and
1418 matched against the declared font-size of the font, using the same
1419 absolute coordinate space for both of the matched values. Values have the
1420 following meanings:
1422 <dl>
1423 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1425 <dd> An <a
1426 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1427 refers to an entry in a table of font sizes computed and kept by the user
1428 agent. Possible values are:
1429 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1431 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1433 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1434 keyword is interpreted relative to the table of font sizes and the
1435 computed ‘<a href="#propdef-font-size"><code
1436 class=property>font-size</code></a>’ of the parent element. Possible
1437 values are:
1438 <p> [ larger | smaller ]
1440 <p> For example, if the parent element has a font size of ‘<code
1441 class=property>medium</code>’, a value of ‘<code
1442 class=property>larger</code>’ will make the font size of the current
1443 element be ‘<code class=property>large</code>’. If the parent
1444 element's size is not close to a table entry, the user agent is free to
1445 interpolate between table entries or round off to the closest one. The
1446 user agent may have to extrapolate table values if the numerical value
1447 goes beyond the keywords.
1449 <dt><dfn id=length-size-value><var><length></var></dfn>
1451 <dd>A length value specifies an absolute font size (independent of the
1452 user agent's font table). Negative lengths are illegal.
1454 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1456 <dd>A percentage value specifies an absolute font size relative to the
1457 parent element's font size. Use of percentage values, or values in
1458 ‘<code class=property>em</code>’s, leads to more robust and
1459 cascadable style sheets.
1460 </dl>
1462 <p>The following table provides user agent guidelines for the absolute-size
1463 scaling factor and their mapping to HTML heading and absolute font-sizes.
1464 The ‘<code class=property>medium</code>’ value is used as the
1465 reference middle value. The user agent may fine-tune these values for
1466 different fonts or different types of display devices.
1468 <table class=data>
1469 <thead>
1470 <tr>
1471 <th>CSS absolute-size values
1473 <th>xx-small
1475 <th>x-small
1477 <th>small
1479 <th>medium
1481 <th>large
1483 <th>x-large
1485 <th>xx-large
1487 <th>
1489 <tbody>
1490 <tr>
1491 <th>scaling factor
1493 <td>3/5
1495 <td>3/4
1497 <td>8/9
1499 <td>1
1501 <td>6/5
1503 <td>3/2
1505 <td>2/1
1507 <td>3/1
1509 <tr>
1510 <th>HTML headings
1512 <td>h6
1514 <td>
1516 <td>h5
1518 <td>h4
1520 <td>h3
1522 <td>h2
1524 <td>h1
1526 <td>
1528 <tr>
1529 <th>HTML font sizes
1531 <td>1
1533 <td>
1535 <td>2
1537 <td>3
1539 <td>4
1541 <td>5
1543 <td>6
1545 <td>7
1546 </table>
1548 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1549 applying these guidelines should nevertheless avoid creating font-size
1550 resulting in less than 9 device pixels per EM unit on a computer
1551 display.</em>
1553 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1554 factor between adjacent indexes was 1.5 which user experience proved to be
1555 too large. In CSS2, the suggested scaling factor for computer screen
1556 between adjacent indexes was 1.2 which still created issues for the small
1557 sizes. The new scaling factor varies between each index to provide a
1558 better readability.</em>
1560 <p>The actual value of this property may differ from the computed value due
1561 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1562 class=property>font-size-adjust</code></a>’ and the unavailability of
1563 certain font sizes.
1565 <p>Child elements inherit the computed <a class=noxref
1566 href="#font-size-prop"> <span class=property>‘<code
1567 class=property>font-size</code>’</span></a> value (otherwise, the effect
1568 of <a class=noxref href="#font-size-adjust-prop"><span
1569 class=property>‘<code
1570 class=property>font-size-adjust</code>’</span></a> would compound).
1572 <div class=example>
1573 <p style="display:none">Example(s):</p>
1575 <pre>p { font-size: 12pt; }
1576 blockquote { font-size: larger }
1577 em { font-size: 150% }
1578 em { font-size: 1.5em }
1579 </pre>
1580 </div>
1581 <!-- prop: font-size-adjust -->
1583 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1584 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1586 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1587 <tbody>
1588 <tr>
1589 <td>Name:
1591 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1593 <tr>
1594 <td>Value:
1596 <td><a href="#font-size-adjust-none-value"
1597 title="none!!font-size-adjust">none</a> | <a
1598 href="#font-size-adjust-auto-value"
1599 title="auto!!font-size-adjust">auto</a> | <a
1600 href="#aspect-ratio-value"><var><number></var></a>
1602 <tr>
1603 <td>Initial:
1605 <td>none
1607 <tr>
1608 <td>Applies to:
1610 <td>all elements
1612 <tr>
1613 <td>Inherited:
1615 <td>yes
1617 <tr>
1618 <td>Percentages:
1620 <td>N/A
1622 <tr>
1623 <td>Media:
1625 <td>visual
1627 <tr>
1628 <td>Computed value:
1630 <td>as specified
1632 <tr>
1633 <td>Animatable:
1635 <td>as <a
1636 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1637 </table>
1639 <p>For any given font size, the apparent size and legibility of text varies
1640 across fonts. For scripts such as Latin or Cyrillic that distinguish
1641 between upper and lowercase letters, the relative height of lowercase
1642 letters compared to their uppercase counterparts is a determining factor
1643 of legibility. This is commonly referred to as the <a class=index-def
1644 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1645 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1646 the x-height of a font divided by the font size.
1648 <p>In situations where font fallback occurs, fallback fonts may not share
1649 the same aspect ratio as the desired font family and will thus appear less
1650 readable. The font-size-adjust property is a way to preserve the
1651 readability of text when font fallback occurs. It does this by adjusting
1652 the font-size so that the x-height is the same regardless of the font
1653 used.
1655 <div class=example>
1656 <p>The style defined below defines Verdana as the desired font family, but
1657 if Verdana is not available Futura or Times will be used.</p>
1659 <pre>p {
1660 font-family: Verdana, Futura, Times;
1661 }
1663 <p>Lorem ipsum dolor sit amet, ...</p>
1664 </pre>
1666 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1667 relatively tall compared to uppercase letters, so at small sizes text
1668 appears legible. Times has a lower aspect ratio and so if fallback
1669 occurs, the text will be less legible at small sizes than Verdana.</p>
1670 </div>
1672 <p>How text rendered in each of these fonts compares is shown below, the
1673 columns show text rendered in Verdana, Futura and Times. The same
1674 font-size value is used across cells within each row and red lines are
1675 included to show the differences in x-height. In the upper half each row
1676 is rendered in the same font-size value. The same is true for the lower
1677 half but in this half the font-size-adjust property is also set so that
1678 the actual font size is adjusted to preserve the x-height across each row.
1679 Note how small text remains relatively legible across each row in the
1680 lower half.
1682 <div class=figure><img alt="text with and without font-size-adjust"
1683 src=fontsizeadjust.png>
1684 <p class=caption>Text with and without the use of font-size-adjust
1685 </div>
1687 <p>This property allows authors to specify an <a
1688 href="#aspect-value"><i>aspect value</i></a> for an element that will
1689 effectively preserve the x-height of the first choice font, whether it is
1690 substituted or not. Values have the following meanings:
1692 <dl>
1693 <dt><dfn id=font-size-adjust-none-value
1694 title="none!!font-size-adjust">none</dfn>
1696 <dd>Do not preserve the font's x-height.
1698 <dt><dfn id=font-size-adjust-auto-value
1699 title="auto!!font-size-adjust">auto</dfn>
1701 <dd>Behaves just like <number>, except the number used is the <a
1702 href="#aspect-value"><i>aspect value</i></a> calculated by user agents
1703 for the first font in the list of fonts defined for the initial value of
1704 the <a href="#propdef-font-family" title="font-family!!property">‘<code
1705 class=property>font-family</code>’</a> property. Effectively this is
1706 the default font used for basic Latin text when <a
1707 href="#propdef-font-family" title="font-family!!property">‘<code
1708 class=property>font-family</code>’</a> is not otherwise specified. It
1709 does not vary based on document content and it is not calculated based on
1710 the computed value of <a href="#propdef-font-family"
1711 title="font-family!!property">‘<code
1712 class=property>font-family</code>’</a> for a given element.
1713 <p class=note>Authors can use this value to specify that font size should
1714 be normalized across fonts based on the x-height without the need to
1715 specify the aspect value explicitly.</p>
1717 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1719 <dd>Specifies the <a href="#aspect-value"><i>aspect value</i></a> used in
1720 the calculation below to calculate the adjusted font size:
1721 <pre>c = ( a / a' ) s
1722 </pre>
1724 <p>where:</p>
1726 <pre>s = font-size value
1727 a = <a href="#aspect-value"><i>aspect value</i></a> as specified by the font-size-adjust property
1728 a' = <a href="#aspect-value"><i>aspect value</i></a> of actual font
1729 c = adjusted font-size to use
1730 </pre>
1732 <p>This value applies to any font that is selected but in typical usage
1733 it should be based on the <a href="#aspect-value"><i>aspect
1734 value</i></a> of the first font in the font-family list. If this is
1735 specified accurately, the <tt>(a/a')</tt> term in the formula above is
1736 effectively 1 for the first font and no adjustment occurs. If the value
1737 is specified inaccurately, text rendered using the first font in the
1738 family list will display differently in older user agents that don't
1739 support font-size-adjust.</p>
1740 </dl>
1742 <p>The value of ‘<a href="#propdef-font-size-adjust"><code
1743 class=property>font-size-adjust</code></a>’ affects the size of relative
1744 units that are based on font metrics of the <a
1745 href="#first-available-font"><i>first available font</i></a> such as
1746 <code>ex</code> and <code>ch</code> but does not affect the size of
1747 <code>em</code> units.
1749 <p>Authors can calculate the <a href="#aspect-value"><i>aspect
1750 value</i></a> for a given font by comparing spans with the same content
1751 but different font-size-adjust properties. If the same font-size is used,
1752 the spans will match when the font-size-adjust value is accurate for the
1753 given font.
1755 <div class=example>
1756 <p>Two spans with borders are used to determine the <a
1757 href="#aspect-value"><i>aspect value</i></a> of a font. The font-size is
1758 the same for both spans but the font-size-adjust property is specified
1759 only for the right span. Starting with a value of 0.5, the aspect value
1760 can be adjusted until the borders around the two letters line up.</p>
1762 <pre>p {
1763 font-family: Futura;
1764 font-size: 500px;
1765 }
1767 span {
1768 border: solid 1px red;
1769 }
1771 .adjust {
1772 font-size-adjust: 0.5;
1773 }
1775 <p><span>b</span><span class="adjust">b</span></p>
1776 </pre>
1778 <div class=figure><img alt="Futura with an <i>aspect value</i> of 0.5"
1779 src=beforefontsizeadjust.png>
1780 <p class=caption>Futura with an <a href="#aspect-value"><i>aspect
1781 value</i></a> of 0.5
1782 </div>
1784 <p>The box on the right is a bit bigger than the one on the left, so the
1785 <a href="#aspect-value"><i>aspect value</i></a> of this font is something
1786 less than 0.5. Adjust the value until the boxes align.</p>
1787 </div>
1788 <!-- prop: font -->
1790 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1791 <a href="#propdef-font">font</a> property</h3>
1793 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1794 <tbody>
1795 <tr>
1796 <td>Name:
1798 <td><dfn id=propdef-font>font</dfn>
1800 <tr>
1801 <td>Value:
1803 <td>[ [ <var><<a href="#propdef-font-style"
1804 title="font-style!!property">‘<code
1805 class=property>font-style</code>’</a>></var> || <a
1806 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1807 || <var><<a href="#propdef-font-weight"
1808 title="font-weight!!property">‘<code
1809 class=property>font-weight</code>’</a>></var> || <var><<a
1810 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1811 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1812 href="#propdef-font-size"><code
1813 class=property>font-size</code></a>’></var> [ / <var><‘<code
1814 class=property>line-height</code>’></var> ]? <var><<a
1815 href="#propdef-font-family" title="font-family!!property">‘<code
1816 class=property>font-family</code>’</a>></var> ] | caption | icon |
1817 menu | message-box | small-caption | status-bar
1819 <tr>
1820 <td>Initial:
1822 <td>see individual properties
1824 <tr>
1825 <td>Applies to:
1827 <td>all elements
1829 <tr>
1830 <td>Inherited:
1832 <td>yes
1834 <tr>
1835 <td>Percentages:
1837 <td>see individual properties
1839 <tr>
1840 <td>Media:
1842 <td>visual
1844 <tr>
1845 <td>Computed value:
1847 <td>see individual properties
1849 <tr>
1850 <td>Animatable:
1852 <td>see individual properties
1853 </table>
1855 <p>The <span class=property>‘<a href="#propdef-font"><code
1856 class=property>font</code></a>’</span> property is, except as described
1857 below, a shorthand property for setting <a href="#propdef-font-style"
1858 title="font-style!!property">‘<code
1859 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1860 title="font-variant!!property">‘<code
1861 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1862 title="font-weight!!property">‘<code
1863 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1864 title="font-stretch!!property">‘<code
1865 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1866 href="#propdef-font-size"><code
1867 class=property>font-size</code></a>’</span>, <a class=property
1868 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1869 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1870 title="font-family!!property">‘<code
1871 class=property>font-family</code>’</a> at the same place in the
1872 stylesheet. Values for the <a href="#propdef-font-variant"
1873 title="font-variant!!property">‘<code
1874 class=property>font-variant</code>’</a> property may also be included
1875 but only those supported in CSS 2.1, none of the <a
1876 href="#propdef-font-variant" title="font-variant!!property">‘<code
1877 class=property>font-variant</code>’</a> values added in this
1878 specification can be used in the <span class=property>‘<a
1879 href="#propdef-font"><code class=property>font</code></a>’</span>
1880 shorthand:
1882 <pre
1883 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1885 <p>The syntax of this property is based on a traditional typographical
1886 shorthand notation to set multiple properties related to fonts.
1888 <p>All subproperties of the ‘<a href="#propdef-font"><code
1889 class=property>font</code></a>’ property are first reset to their
1890 initial values, including those listed above plus <span
1891 class=property>‘<a href="#propdef-font-size-adjust"><code
1892 class=property>font-size-adjust</code></a>’</span>, <span
1893 class=property>‘<a href="#propdef-font-kerning"><code
1894 class=property>font-kerning</code></a>’</span>, subproperties of <a
1895 href="#propdef-font-variant" title="font-variant!!property">‘<code
1896 class=property>font-variant</code>’</a> and and <span>‘<a
1897 href="#propdef-font-language-override"><code
1898 class=property>font-language-override</code></a>’</span>. Then, those
1899 properties that are given explicit values in the <span
1900 class=property>‘<a href="#propdef-font"><code
1901 class=property>font</code></a>’</span> shorthand are set to those
1902 values. For a definition of allowed and initial values, see the previously
1903 defined properties. For reasons of backwards compatibility, it is not
1904 possible to set <span class=property>‘<a
1905 href="#propdef-font-size-adjust"><code
1906 class=property>font-size-adjust</code></a>’</span> to anything other
1907 than its initial value using the <span class=property>‘<a
1908 href="#propdef-font"><code class=property>font</code></a>’</span>
1909 shorthand property; instead, use the individual property.
1911 <div class=example>
1912 <p style="display:none">Example(s):</p>
1914 <pre>p { font: 12pt/14pt sans-serif }
1915 p { font: 80% sans-serif }
1916 p { font: x-large/110% "new century schoolbook", serif }
1917 p { font: bold italic large Palatino, serif }
1918 p { font: normal small-caps 120%/120% fantasy }
1919 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1920 </pre>
1922 <p> In the second rule, the font size percentage value (‘<code
1923 class=css>80%</code>’) refers to the computed ‘<a
1924 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1925 the parent element. In the third rule, the line height percentage
1926 (‘<code class=css>110%</code>’) refers to the font size of the
1927 element itself.
1929 <p>The first three rules do not specify the <a
1930 href="#propdef-font-variant" title="font-variant!!property">‘<code
1931 class=property>font-variant</code>’</a> and <a
1932 href="#propdef-font-weight" title="font-weight!!property">‘<code
1933 class=property>font-weight</code>’</a> explicitly, so these properties
1934 receive their initial values (<span title="normal value">‘<code
1935 class=property>normal</code>’</span>). Notice that the font family name
1936 "new century schoolbook", which contains spaces, is enclosed in quotes.
1937 The fourth rule sets the <a href="#propdef-font-weight"
1938 title="font-weight!!property">‘<code
1939 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1940 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1941 title="font-style!!property">‘<code
1942 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1943 class=property>italic</code></a>’, and implicitly sets <a
1944 href="#propdef-font-variant" title="font-variant!!property">‘<code
1945 class=property>font-variant</code>’</a> to <a
1946 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1947 class=property>normal</code>’</a>.
1949 <p> The fifth rule sets the <a href="#propdef-font-variant"
1950 title="font-variant!!property">‘<code
1951 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1952 class=property>small-caps</code></a>’), the <span class=property>‘<a
1953 href="#propdef-font-size"><code
1954 class=property>font-size</code></a>’</span> (120% of the parent's font
1955 size), the <a class=property
1956 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1957 class=property>line-height</code>’</a> (120% of the font size) and the
1958 <a href="#propdef-font-family" title="font-family!!property">‘<code
1959 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1960 class=property>fantasy</code></a>’). It follows that the keyword <span
1961 title="normal value">‘<code class=property>normal</code>’</span>
1962 applies to the two remaining properties: <a href="#propdef-font-style"
1963 title="font-style!!property">‘<code
1964 class=property>font-style</code>’</a> and <a
1965 href="#propdef-font-weight" title="font-weight!!property">‘<code
1966 class=property>font-weight</code>’</a>.
1968 <p>The sixth rule sets the <a href="#propdef-font-style"
1969 title="font-style!!property">‘<code
1970 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1971 title="font-stretch!!property">‘<code
1972 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1973 href="#propdef-font-size"><code
1974 class=property>font-size</code></a>’</span>, and <a
1975 href="#propdef-font-family" title="font-family!!property">‘<code
1976 class=property>font-family</code>’</a>, the other font properties being
1977 set to their initial values.
1978 </div>
1980 <p>Since the <a href="#propdef-font-stretch"
1981 title="font-stretch!!property">‘<code
1982 class=property>font-stretch</code>’</a> property was not defined in CSS
1983 2.1, when using <a href="#propdef-font-stretch"
1984 title="font-stretch!!property">‘<code
1985 class=property>font-stretch</code>’</a> values within ‘<a
1986 href="#propdef-font"><code class=property>font</code></a>’ rules,
1987 authors should include a extra version compatible with older user agents:
1989 <pre>p {
1990 font: 80% sans-serif; /* for older user agents */
1991 font: condensed 80% sans-serif;
1992 }</pre>
1994 <p>The following values refer to system fonts:
1996 <dl>
1997 <dt><strong>caption</strong>
1999 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
2000 etc.).
2002 <dt><strong>icon</strong>
2004 <dd>The font used to label icons.
2006 <dt><strong>menu</strong>
2008 <dd>The font used in menus (e.g., dropdown menus and menu lists).
2010 <dt><strong>message-box</strong>
2012 <dd>The font used in dialog boxes.
2014 <dt><strong>small-caption</strong>
2016 <dd>The font used for labeling small controls.
2018 <dt><strong>status-bar</strong>
2020 <dd>The font used in window status bars.
2021 </dl>
2023 <p>System fonts may only be set as a whole; that is, the font family, size,
2024 weight, style, etc. are all set at the same time. These values may then be
2025 altered individually if desired. If no font with the indicated
2026 characteristics exists on a given platform, the user agent should either
2027 intelligently substitute (e.g., a smaller version of the ‘<code
2028 class=property>caption</code>’ font might be used for the ‘<code
2029 class=property>small-caption</code>’ font), or substitute a user agent
2030 default font. As for regular fonts, if, for a system font, any of the
2031 individual properties are not part of the operating system's available
2032 user preferences, those properties should be set to their initial values.
2034 <p>That is why this property is "almost" a shorthand property: system fonts
2035 can only be specified with this property, not with <a
2036 href="#propdef-font-family" title="font-family!!property">‘<code
2037 class=property>font-family</code>’</a> itself, so <span
2038 class=property>‘<a href="#propdef-font"><code
2039 class=property>font</code></a>’</span> allows authors to do more than
2040 the sum of its subproperties. However, the individual properties such as
2041 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2042 class=property>font-weight</code>’</a> are still given values taken from
2043 the system font, which can be independently varied.
2045 <p>Note that the keywords used for the system fonts listed above are only
2046 treated as keywords when they occur in the initial position, in other
2047 positions the same string is treated as part of the font family name:
2049 <pre> font: menu; /* use the font settings for system menus */
2050 font: large menu; /* use a font family named "menu" */</pre>
2052 <div class=example>
2053 <p style="display:none">Example(s):</p>
2055 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2056 button p { font: menu }
2057 button p em { font-weight: bolder }
2058 </pre>
2060 <p>If the font used for dropdown menus on a particular system happened to
2061 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2062 that were descendants of BUTTON would be displayed as if this rule were
2063 in effect:
2065 <pre>button p { font: 600 9pt Charcoal }
2066 </pre>
2068 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2069 class=property>font</code></a>’</span> shorthand resets to its initial
2070 value any property not explicitly given a value, this has the same effect
2071 as this declaration:
2073 <pre>button p {
2074 font-style: normal;
2075 font-variant: normal;
2076 font-weight: 600;
2077 font-size: 9pt;
2078 line-height: normal;
2079 font-family: Charcoal
2080 }
2081 </pre>
2082 </div>
2083 <!-- prop: font-synthesis -->
2085 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2086 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2087 property</h3>
2089 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2090 <tbody>
2091 <tr>
2092 <td>Name:
2094 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2096 <tr>
2097 <td>Value:
2099 <td>none | [ weight || style ]
2101 <tr>
2102 <td>Initial:
2104 <td>weight style
2106 <tr>
2107 <td>Applies to:
2109 <td>all elements
2111 <tr>
2112 <td>Inherited:
2114 <td>yes
2116 <tr>
2117 <td>Percentages:
2119 <td>N/A
2121 <tr>
2122 <td>Media:
2124 <td>visual
2126 <tr>
2127 <td>Computed value:
2129 <td>as specified
2131 <tr>
2132 <td>Animatable:
2134 <td>no
2135 </table>
2137 <p>This property controls whether user agents are allowed to synthesize
2138 bold or oblique font faces when a font family lacks bold or italic faces.
2139 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2140 specified, user agents must not synthesize bold faces and if ‘<code
2141 class=property>style</code>’ is not specified user agents must not
2142 synthesize italic faces. A value of ‘<code class=property>none</code>’
2143 disallows all synthetic faces.
2145 <div class=example>
2146 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2148 <pre>*:lang(ar) { font-synthesis: none; }
2149 </pre>
2150 </div>
2152 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2154 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2155 id=at-font-face-rule style="font-weight: inherit; font-style:
2156 inherit"><code>@font-face</code></dfn> rule</h3>
2158 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2159 for linking to fonts that are automatically fetched and activated when
2160 needed. This allows authors to select a font that closely matches the
2161 design goals for a given page rather than limiting the font choice to a
2162 set of fonts available on all platforms. A set of font descriptors define
2163 the location of a font resource, either locally or externally, along with
2164 the style characteristics of an individual face. Multiple <a
2165 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2166 construct font families with a variety of faces. Using CSS font matching
2167 rules, a user agent can selectively download only those faces that are
2168 needed for a given piece of text.
2170 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2171 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2172 at-keyword followed by a block of descriptor declarations. In terms of the
2173 grammar, this specification defines the following productions:
2175 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2176 : <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>*
2177 ;
2179 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2180 : <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>
2181 ;</pre>
2183 <p>The following new definitions are introduced:
2185 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2186 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2188 <p>The following new token is introduced:
2190 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2192 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2193 specifies a value for every font descriptor, either implicitly or
2194 explicitly. Those not given explicit values in the rule take the initial
2195 value listed with each descriptor in this specification. These descriptors
2196 apply solely within the context of the <a
2197 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2198 are defined, and do not apply to document language elements. There is no
2199 notion of which elements the descriptors apply to or whether the values
2200 are inherited by child elements. When a given descriptor occurs multiple
2201 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2202 rule, only the last descriptor declaration is used and all prior
2203 declarations for that descriptor are ignored.
2205 <div class=example>
2206 <p>To use a downloadable font called Gentium:</p>
2208 <pre>
2209 @font-face {
2210 font-family: Gentium;
2211 src: url(http://example.com/fonts/Gentium.woff);
2212 }
2214 p { font-family: Gentium, serif; }
2215 </pre>
2217 <p>The user agent will download Gentium and use it when rendering text
2218 within paragraph elements. If for some reason the site serving the font
2219 is unavailable, the default serif font will be used.</p>
2220 </div>
2222 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2223 rules define a set of fonts available for use within the documents that
2224 contain these rules. When font matching is done, fonts defined using these
2225 rules are considered before other available fonts on a system.
2227 <p>Downloaded fonts are only available to documents that reference them.
2228 The process of activating these fonts must not make them available to
2229 other applications or to documents that don't directly link to the same
2230 font. User agent implementers might consider it convenient to use
2231 downloaded fonts when rendering characters in other documents for which no
2232 other available font exists as part of the <a
2233 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2234 However, this would cause a security leak since the contents of one page
2235 would be able to affect other pages, something an attacker could use as an
2236 attack vector. These restrictions do not affect caching behavior, fonts
2237 are cached the same way other web resources are cached.
2239 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2240 properties in a declaration block, declarations of any descriptors that
2241 are not supported by the user agent must be ignored. <a
2242 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2243 font-family and src descriptor; if either of these are missing, the <a
2244 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2245 must be ignored entirely.
2247 <p>In cases where user agents have limited platform resources or implement
2248 the ability to disable downloadable font resources, <a
2249 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2250 ignored; the behavior of individual descriptors as defined in this
2251 specification should not be altered.
2253 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2254 href="#descdef-font-family">font-family</a> descriptor</h3>
2256 <table class=descdef>
2257 <tbody>
2258 <tr>
2259 <td>Name:
2261 <td><dfn id=descdef-font-family
2262 title="font-family!!descriptor">font-family</dfn>
2264 <tr>
2265 <td>Value:
2267 <td><a href="#family-name-value"><var><family-name></var></a>
2269 <tr>
2270 <td><em>Initial:</em>
2272 <td>N/A
2273 </table>
2275 <p>This descriptor defines the font family name that will be used in all
2276 CSS font family name matching. It is required for the <a
2277 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2278 overrides the font family names contained in the underlying font data. If
2279 the font family name is the same as a font family available in a given
2280 user's environment, it effectively hides the underlying font for documents
2281 that use the stylesheet. This permits a web author to freely choose
2282 font-family names without worrying about conflicts with font family names
2283 present in a given user's environment. Likewise, platform substitutions
2284 for a given font family name must not be used.
2286 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2287 href="#descdef-src">src</a> descriptor</h3>
2289 <table class=descdef>
2290 <tbody>
2291 <tr>
2292 <td>Name:
2294 <td><dfn id=descdef-src>src</dfn>
2296 <tr>
2297 <td>Value:
2299 <td>[ <url> [format(<string> #)]? | <a
2300 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2302 <tr>
2303 <td><em>Initial:</em>
2305 <td>N/A
2306 </table>
2308 <p>This descriptor specifies the resource containing font data. It is
2309 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2310 rule to be valid. Its value is a prioritized, comma-separated list of
2311 external references or locally-installed font face names. When a font is
2312 needed the user agent iterates over the set of references listed, using
2313 the first one it can successfully activate. Fonts containing invalid data
2314 or local font faces that are not found are ignored and the user agent
2315 loads the next font in the list.
2317 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2318 resolved relative to the location of the style sheet containing the <a
2319 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2320 SVG fonts, the URL points to an element within a document containing SVG
2321 font definitions. If the element reference is omitted, a reference to the
2322 first defined font is implied. Similarly, font container formats that can
2323 contain more than one font must load one and only one of the fonts for a
2324 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2325 Fragment identifiers are used to indicate which font to load. If a
2326 container format lacks a defined fragment identifier scheme,
2327 implementations should use a simple 1-based indexing scheme (e.g.
2328 "font-collection#1" for the first font, "font-collection#2" for the second
2329 font).
2331 <pre>
2332 src: url(fonts/simple.woff); /* load simple.woff relative to stylesheet location */
2333 src: url(/fonts/simple.woff); /* load simple.woff from absolute location */
2334 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2335 </pre>
2337 <p>External references consist of a URL, followed by an optional hint
2338 describing the format of the font resource referenced by that URL. The
2339 format hint contains a comma-separated list of format strings that denote
2340 well-known font formats. Conformant user agents must skip downloading a
2341 font resource if the format hints indicate only unsupported or unknown
2342 font formats. If no format hints are supplied, the user agent should
2343 download the font resource.
2345 <pre>
2346 /* load WOFF font if possible, otherwise use OpenType font */
2347 @font-face {
2348 font-family: bodytext;
2349 src: url(ideal-sans-serif.woff) format("woff"),
2350 url(basic-sans-serif.ttf) format("opentype");
2351 }
2352 </pre>
2354 <p>Format strings defined by this specification:
2356 <table class=data id=fontformats>
2357 <thead>
2358 <tr>
2359 <th>String
2361 <th>Font Format
2363 <th>Common extensions
2365 <tbody>
2366 <tr>
2367 <th>"woff"
2369 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2371 <td>.woff
2373 <tr>
2374 <th>"truetype"
2376 <td><a
2377 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2379 <td>.ttf
2381 <tr>
2382 <th>"opentype"
2384 <td><a
2385 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2387 <td>.ttf, .otf
2389 <tr>
2390 <th>"embedded-opentype"
2392 <td><a
2393 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2394 OpenType</a>
2396 <td>.eot
2398 <tr>
2399 <th>"svg"
2401 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2403 <td>.svg, .svgz
2404 </table>
2406 <p>Given the overlap in common usage between TrueType and OpenType, the
2407 format hints "truetype" and "opentype" must be considered as synonymous; a
2408 format hint of "opentype" does not imply that the font contains Postscript
2409 CFF style glyph data or that it contains OpenType layout information (see
2410 <a href="#platform-props-to-css">Appendix A</a> for more background on
2411 this).
2413 <p>When authors would prefer to use a locally available copy of a given
2414 font and download it if it's not, <code>local()</code> can be used. The
2415 locally-installed <dfn
2416 id=font-face-name-value><var><font-face-name></var></dfn> argument
2417 to <code>local()</code> is a format-specific string that uniquely
2418 identifies a single font face within a larger family. The syntax for a <a
2419 href="#font-face-name-value"><var><font-face-name></var></a> is a
2420 unique font face name enclosed by "local(" and ")". The name can
2421 optionally be enclosed in quotes. If unquoted, the unquoted font family
2422 name processing conventions apply; the name must be a sequence of
2423 identifiers separated by whitespace which is converted to a string by
2424 joining the identifiers together separated by a single space.
2426 <pre>
2427 /* regular face of Gentium */
2428 @font-face {
2429 font-family: MyGentium;
2430 src: local(Gentium), /* use locally available Gentium */
2431 url(Gentium.woff); /* otherwise, download it */
2432 }
2433 </pre>
2435 <p>For OpenType and TrueType fonts, this string is used to match only the
2436 Postscript name or the full font name in the name table of locally
2437 available fonts. Which type of name is used varies by platform and font,
2438 so authors should include both of these names to assure proper matching
2439 across platforms. Platform substitutions for a given font name must not be
2440 used.
2442 <pre>
2443 /* bold face of Gentium */
2444 @font-face {
2445 font-family: MyGentium;
2446 src: local(Gentium Bold), /* full font name */
2447 local(Gentium-Bold), /* Postscript name */
2448 url(GentiumBold.woff); /* otherwise, download it */
2449 font-weight: bold;
2450 }
2451 </pre>
2453 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2454 specifies the characteristics of a single font within a family, the unique
2455 name used with <code>local()</code> specifies a single font, not an entire
2456 font family. Defined in terms of OpenType font data, the Postscript name
2457 is found in the font's <a
2458 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2459 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2460 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2461 Postscript name is the commonly used key for all fonts on OSX and for
2462 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2463 used as a unique key for fonts with TrueType glyphs on Windows.
2465 <p>For OpenType fonts with multiple localizations of the full font name,
2466 the US English version is used (language ID = 0x409 for Windows and
2467 language ID = 0 for Macintosh) or the first localization when a US English
2468 full font name is not available (the OpenType specification recommends
2469 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2470 fonts minimally include US English names</a>). User agents that also match
2471 other full font names, e.g. matching the Dutch name when the current
2472 system locale is set to Dutch, are considered non-conformant. This is done
2473 not to prefer English but to avoid matching inconsistencies across font
2474 versions and OS localizations, since font style names (e.g. "Bold") are
2475 frequently localized into many languages and the set of localizations
2476 available varies widely across platform and font version. User agents that
2477 match a concatenation of family name (nameID = 1) with style name (nameID
2478 = 2) are considered non-conformant.
2480 <p>This also allows for referencing faces that belong to larger families
2481 that cannot otherwise be referenced.
2483 <div class=example>
2484 <p>Use a local font or reference an SVG font in another document:</p>
2486 <pre>
2487 @font-face {
2488 font-family: Headline;
2489 src: local(Futura-Medium),
2490 url(fonts.svg#MyGeometricModern) format("svg");
2491 }
2492 </pre>
2494 <p>Create an alias for local Japanese fonts on different platforms:</p>
2496 <pre>
2497 @font-face {
2498 font-family: jpgothic;
2499 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2500 }
2501 </pre>
2503 <p>Reference a font face that cannot be matched within a larger family:</p>
2505 <pre>
2506 @font-face {
2507 font-family: Hoefler Text Ornaments;
2508 /* has the same font properties as Hoefler Text Regular */
2509 src: local(HoeflerText-Ornaments);
2510 }
2511 </pre>
2513 <p>Since localized fullnames never match, a document with the header style
2514 rules below would always render using the default serif font, regardless
2515 whether a particular system locale parameter is set to Finnish or not:</p>
2517 <pre>
2518 @font-face {
2519 font-family: SectionHeader;
2520 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2521 font-weight: bold;
2522 }
2524 h2 { font-family: SectionHeader, serif; }
2525 </pre>
2527 <p>A conformant user agent would never load the font ‘<code
2528 class=css>gentium.eot</code>’ in the example below, since it is
2529 included in the first definition of the ‘<a href="#descdef-src"><code
2530 class=property>src</code></a>’ descriptor which is overridden by the
2531 second definition in the same <a
2532 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2534 <pre>
2535 @font-face {
2536 font-family: MainText;
2537 src: url(gentium.eot); /* for use with older user agents */
2538 src: local("Gentium"), url(gentium.woff); /* Overrides src definition */
2539 }
2540 </pre>
2541 </div>
2543 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2544 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2545 href="#descdef-font-weight">font-weight</a>, <a
2546 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2548 <table class=descdef>
2549 <tbody>
2550 <tr>
2551 <td>Name:
2553 <td><dfn id=descdef-font-style
2554 title="font-style!!descriptor">font-style</dfn>
2556 <tr>
2557 <td>Value:
2559 <td>normal | italic | oblique
2561 <tr>
2562 <td><em>Initial:</em>
2564 <td>normal
2565 </table>
2567 <table class=descdef>
2568 <tbody>
2569 <tr>
2570 <td>Name:
2572 <td><dfn id=descdef-font-weight
2573 title="font-weight!!descriptor">font-weight</dfn>
2575 <tr>
2576 <td>Value:
2578 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2580 <tr>
2581 <td><em>Initial:</em>
2583 <td>normal
2584 </table>
2586 <table class=descdef>
2587 <tbody>
2588 <tr>
2589 <td>Name:
2591 <td><dfn id=descdef-font-stretch
2592 title="font-stretch!!descriptor">font-stretch</dfn>
2594 <tr>
2595 <td>Value:
2597 <td>normal | ultra-condensed | extra-condensed | condensed |
2598 semi-condensed | semi-expanded | expanded | extra-expanded |
2599 ultra-expanded
2601 <tr>
2602 <td><em>Initial:</em>
2604 <td>normal
2605 </table>
2607 <p>These descriptors define the characteristics of a font face and are used
2608 in the process of matching styles to specific faces. For a font family
2609 defined with several <a
2610 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2611 can either download all faces in the family or use these descriptors to
2612 selectively download font faces that match actual styles used in document.
2613 The values for these descriptors are the same as those for the
2614 corresponding font properties except that relative keywords are not
2615 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2616 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2617 these descriptors are omitted, initial values are assumed.
2619 <p>The value for these font face style attributes is used in place of the
2620 style implied by the underlying font data. This allows authors to combine
2621 faces in flexible combinations, even in situations where the original font
2622 data was arranged differently. User agents that implement synthetic
2623 bolding and obliquing must only apply synthetic styling in cases where the
2624 font descriptors imply this is needed, rather than based on the style
2625 attributes implied by the font data.
2627 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2628 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2630 <table class=descdef>
2631 <tbody>
2632 <tr>
2633 <td>Name:
2635 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2637 <tr>
2638 <td>Value:
2640 <td><a href="#urange-value"><var><urange></var></a> #
2642 <tr>
2643 <td><em>Initial:</em>
2645 <td>U+0-10FFFF
2646 </table>
2648 <p>This descriptor defines the set of Unicode codepoints that may be
2649 supported by the font face for which it is declared. The descriptor value
2650 is a comma-delimited list of Unicode range (<a
2651 href="#urange-value"><var><urange></var></a>) values. The union of
2652 these ranges defines the set of codepoints that serves as a hint for user
2653 agents when deciding whether or not to download a font resource for a
2654 given text run.
2656 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2657 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2658 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2659 "U+" or "u+" prefix followed by a codepoint range in one of the three
2660 forms listed below. Ranges that do not fit one of the these forms are
2661 invalid and cause the declaration to be ignored.
2663 <dl>
2664 <dt>single codepoint (e.g. U+416)
2666 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2667 digits
2669 <dt>interval range (e.g. U+400-4ff)
2671 <dd>represented as two hyphen-separated valid Unicode codepoints
2672 indicating the inclusive start and end codepoints of a range
2674 <dt>wildcard range (e.g. U+4??)
2676 <dd>defined by the set of codepoints implied when trailing ‘<code
2677 class=css>?</code>’ characters signify any hexadeximal digit
2678 </dl>
2680 <p>Individual codepoints are written using hexadecimal values that
2681 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2682 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2683 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2684 interval ranges, the start and end codepoints are valid Unicode values and
2685 the end codepoint is greater than or equal to the start codepoint.
2687 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2688 "U+???") are valid and equivalent to a wildcard range with an initial zero
2689 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2690 the range of valid Unicode codepoints are invalid. Because of this, the
2691 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2692 characters is five, even though the <a
2693 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2694 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2696 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2697 href="#descdef-unicode-range"><code
2698 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2699 may overlap. The union of these ranges defines the set of codepoints for
2700 which the corresponding font may be used. User agents must not download or
2701 use the font for codepoints outside this set. User agents may normalize
2702 the list of ranges into a list that is different but represents the same
2703 set of codepoints.
2705 <p>The associated font might not contain glyphs for the entire set of
2706 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2707 class=property>unicode-range</code></a>’ descriptor. When the font is
2708 used, the <dfn id=effective-character-map>effective character map</dfn> is
2709 the intersection of the codepoints defined by ‘<a
2710 href="#descdef-unicode-range"><code
2711 class=property>unicode-range</code></a>’ with the font's <a
2712 href="#character-map"><em>character map</em></a>. This allows authors to
2713 define supported ranges in terms of broad ranges without worrying about
2714 the precise codepoint ranges supported by the underlying font.
2716 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2717 to define composite fonts</h3>
2719 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2720 with different unicode ranges for the same family and style descriptor
2721 values can be used to create composite fonts that mix the glyphs from
2722 different fonts for different scripts. This can be used to combine fonts
2723 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2724 or it can be used by authors as a way of segmenting a font into fonts for
2725 commonly used characters and less frequently used characters. Since the
2726 user agent will only pull down the fonts it needs this helps reduce page
2727 bandwidth.
2729 <p>If the unicode ranges overlap for a set of <a
2730 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2731 family and style descriptor values, the rules are ordered in the reverse
2732 order they were defined; the last rule defined is the first to be checked
2733 for a given character.
2735 <p>Example ranges for specific languages or characters:
2737 <dl>
2738 <dt>unicode-range: U+A5;
2740 <dd>a single code point, the yen/yuan symbol
2742 <dt>unicode-range: U+0-7F;
2744 <dd>code range for basic ASCII characters
2746 <dt>unicode-range: U+590-5ff;
2748 <dd>code range for Hebrew characters
2750 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2752 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2753 yen/yuan symbol
2754 </dl>
2756 <div class=example>
2757 <p>The BBC provides news services in a wide variety of languages, many
2758 that are not well supported across all platforms. Using an <a
2759 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2760 provide a font for any of these languages, as it already does via a
2761 manual font download.</p>
2763 <pre>
2764 @font-face {
2765 font-family: BBCBengali;
2766 src: url(fonts/BBCBengali.woff) format("woff");
2767 unicode-range: U+00-FF, U+980-9FF;
2768 }
2769 </pre>
2770 </div>
2772 <div class=example>
2773 <p>Technical documents often require a wide range of symbols. The STIX
2774 Fonts project is one project aimed at providing fonts to support a wide
2775 range of technical typesetting in a standardized way. The example below
2776 shows the use of a font that provides glyphs for many of the mathematical
2777 and technical symbol ranges within Unicode:</p>
2779 <pre>
2780 @font-face {
2781 font-family: STIXGeneral;
2782 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2783 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2784 }
2785 </pre>
2786 </div>
2788 <div class=example>
2789 <p>This example shows how an author can override the glyphs used for Latin
2790 characters in a Japanese font with glyphs from a different font. The
2791 first rule specifies no range so it defaults to the entire range. The
2792 range specified in the second rule overlaps but takes precedence because
2793 it is defined later.</p>
2795 <pre>
2796 @font-face {
2797 font-family: JapaneseWithGentium;
2798 src: local(MSMincho);
2799 /* no range specified, defaults to entire range */
2800 }
2802 @font-face {
2803 font-family: JapaneseWithGentium;
2804 src: url(../fonts/Gentium.woff);
2805 unicode-range: U+0-2FF;
2806 }
2807 </pre>
2808 </div>
2810 <div class=example>
2811 <p>Consider a family constructed to optimize bandwidth by separating out
2812 Latin, Japanese and other characters into different font files:</p>
2814 <pre>
2815 /* fallback font - size: 4.5MB */
2816 @font-face {
2817 font-family: DroidSans;
2818 src: url(DroidSansFallback.woff);
2819 /* no range specified, defaults to entire range */
2820 }
2822 /* Japanese glyphs - size: 1.2MB */
2823 @font-face {
2824 font-family: DroidSans;
2825 src: url(DroidSansJapanese.woff);
2826 unicode-range: U+3000-9FFF, U+ff??;
2827 }
2829 /* Latin, Greek, Cyrillic along with some
2830 punctuation and symbols - size: 190KB */
2831 @font-face {
2832 font-family: DroidSans;
2833 src: url(DroidSans.woff);
2834 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2835 }
2836 </pre>
2838 <p>For simple Latin text, only the font for Latin characters is
2839 downloaded:</p>
2841 <pre>
2842 body { font-family: DroidSans; }
2844 <p>This is that</p>
2845 </pre>
2847 <p>In this case the user agent first checks the unicode-range for the font
2848 containing Latin characters (DroidSans.woff). Since all the characters
2849 above are in the range U+0-5FF, the user agent downloads the font and
2850 renders the text with that font.</p>
2852 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2854 <pre>
2855 <p>This &#x21e8; that<p>
2856 </pre>
2858 <p>The user agent again first checks the unicode-range of the font
2859 containing Latin characters. Since U+2000-2300 includes the arrow code
2860 point (U+21E8), the user agent downloads the font. For this character
2861 however the Latin font does not have a matching glyph, so the effective
2862 unicode-range used for font matching excludes this code point. Next, the
2863 user agent evaluates the Japanese font. The unicode-range for the
2864 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2865 user agent does not download the Japanese font. Next the fallback font is
2866 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2867 rule for the fallback font does not define unicode-range so its value
2868 defaults to the range of all Unicode code points. The fallback font is
2869 downloaded and used to render the arrow character.</p>
2870 </div>
2872 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2873 href="#descdef-font-variant">font-variant</a> and <a
2874 href="#descdef-font-feature-settings">font-feature-settings</a>
2875 descriptors</h3>
2877 <table class=descdef>
2878 <tbody>
2879 <tr>
2880 <td>Name:
2882 <td><dfn id=descdef-font-variant
2883 title="font-variant!!descriptor">font-variant</dfn>
2885 <tr>
2886 <td>Value:
2888 <td><a href="#font-variant-normal-value"
2889 title="normal!!font-variant">normal</a> | <a
2890 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2891 <a href="#common-lig-values"><var><common-lig-values></var></a>
2892 || <a
2893 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2894 || <a
2895 href="#historical-lig-values"><var><historical-lig-values></var></a>
2896 || <a
2897 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2898 || <a href="#stylistic"><var
2899 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2900 href="#historical-forms"><var>historical-forms</var></a> || <a
2901 href="#styleset"><var
2902 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2903 href="#character-variant"><var
2904 title=character-variant>character-variant(<feature-value-name>
2905 #)</var></a> || <a href="#swash"><var
2906 title=swash>swash(<feature-value-name>)</var></a> || <a
2907 href="#ornaments"><var
2908 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2909 href="#annotation"><var
2910 title=annotation>annotation(<feature-value-name>)</var></a> || [
2911 <a href="#small-caps"><i>small-caps</i></a> | <a
2912 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2913 href="#petite-caps"><i>petite-caps</i></a> | <a
2914 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2915 href="#unicase"><i>unicase</i></a> | <a
2916 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2917 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2918 || <a
2919 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2920 || <a
2921 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2922 || <a href="#ordinal"><i>ordinal</i></a> || <a
2923 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2924 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2925 || <a
2926 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2927 || <a href="#ruby"><i>ruby</i></a> ]
2929 <tr>
2930 <td><em>Initial:</em>
2932 <td>normal
2933 </table>
2935 <table class=descdef>
2936 <tbody>
2937 <tr>
2938 <td>Name:
2940 <td><dfn id=descdef-font-feature-settings
2941 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2943 <tr>
2944 <td>Value:
2946 <td><a href="#font-feature-settings-normal-value"
2947 title="normal!!font-feature-settings">normal</a> | <a
2948 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2950 <tr>
2951 <td><em>Initial:</em>
2953 <td>normal
2954 </table>
2956 <p>These descriptors define initial settings that apply when the font
2957 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2958 rule is rendered. They do not affect font selection. Values are identical
2959 to those defined for the corresponding <a href="#propdef-font-variant"
2960 title="font-variant!!property">‘<code
2961 class=property>font-variant</code>’</a> and <a
2962 href="#propdef-font-feature-settings"
2963 title="font-feature-settings!!property">‘<code
2964 class=property>font-feature-settings</code>’</a> properties defined
2965 below except that the value ‘<code class=property>inherit</code>’ is
2966 omitted. When multiple font feature descriptors or properties are used,
2967 the cumulative effect on text rendering is detailed in the section <a
2968 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2969 cases where specific values define synthesized fallback for certain <a
2970 href="#propdef-font-variant" title="font-variant!!property">‘<code
2971 class=property>font-variant</code>’</a> subproperties, the same
2972 synthesized fallback applies when used within those values are used with
2973 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2974 class=property>font-variant</code>’</a> descriptor.
2976 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2977 guidelines</h3>
2979 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
2980 designed to allow lazy loading of font resources that are only downloaded
2981 when used within a document. A stylesheet can include <a
2982 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
2983 of fonts of which only a select set are used; user agents must only
2984 download those fonts that are referred to within the style rules
2985 applicable to a given page. User agents that download all fonts defined in
2986 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
2987 considering whether those fonts are in fact used within a page are
2988 considered non-conformant. In cases where a font might be downloaded in
2989 character fallback cases, user agents may download a font if it's
2990 contained within the computed value of <a href="#propdef-font-family"
2991 title="font-family!!property">‘<code
2992 class=property>font-family</code>’</a> for a given text run.
2994 <pre>
2995 @font-face {
2996 font-family: GeometricModern;
2997 src: url(font.woff);
2998 }
3000 p {
3001 /* font will be downloaded for pages with p elements */
3002 font-family: GeometricModern, sans-serif;
3003 }
3005 h2 {
3006 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
3007 font-family: Futura, GeometricModern, sans-serif;
3008 }
3009 </pre>
3011 <p>In cases where textual content is loaded before downloadable fonts are
3012 available, user agents may render text as it would be rendered if
3013 downloadable font resources are not available or they may render text
3014 transparently with fallback fonts to avoid a flash of text using a
3015 fallback font. In cases where the font download fails user agents must
3016 display text, simply leaving transparent text is considered non-conformant
3017 behavior. Authors are advised to use fallback fonts in their font lists
3018 that closely match the metrics of the downloadable fonts to avoid large
3019 page reflows where possible.
3021 <p><a id=same-origin-restriction> </a><a
3022 id=allowing-cross-origin-font-loading> </a>
3024 <h3 id=font-fetching-requirements><span class=secno>4.9 </span>Font
3025 fetching requirements</h3>
3026 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3027 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3028 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3029 -->
3031 <p>For font loads, user agents must use the <a
3032 href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
3033 CORS-enabled fetch</a> method defined by the <a href="#HTML5"
3034 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification for URL's
3035 defined within @font-face rules. When fetching, user agents must use
3036 "Anonymous" mode, set the referrer source to the stylesheet's URL and set
3037 the origin to the URL of the containing document.
3039 <p class=note>The implications of this for authors are that fonts will
3040 typically not be loaded cross-origin unless authors specifically takes
3041 steps to permit cross-origin loads. Sites can explicitly allow cross-site
3042 loading of font data using the <code>Access-Control-Allow-Origin</code>
3043 HTTP header. For other schemes, no explicit mechanism to allow
3044 cross-origin loading, beyond what is permitted by the <a
3045 href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
3046 CORS-enabled fetch</a> method, is defined or required.
3048 <div class=example> For the examples given below, assume that a document is
3049 located at <code>http://example.com/page.html</code> and all URL's link to
3050 valid font resources supported by the user agent. Fonts defined with the
3051 ‘<a href="#descdef-src"><code class=property>src</code></a>’
3052 descriptor values below will be loaded:
3053 <pre>/* same origin (i.e. domain, scheme, port match document) */
3054 src: url(fonts/simple.woff);
3055 src: url(//fonts/simple.woff);
3057 /* data url's with no redirects are treated as same origin */
3058 src: url("data:application/font-woff;base64,...");
3060 /* cross origin, different domain */
3061 /* Access-Control-Allow-Origin response header set to '*' */
3062 src: url(http://another.example.com/fonts/simple.woff);
3063 </pre>
3064 Fonts defined with the ‘<a href="#descdef-src"><code
3065 class=property>src</code></a>’ descriptor values below will fail to
3066 load:
3067 <pre>/* cross origin, different scheme */
3068 /* no Access-Control-xxx headers in response */
3069 src: url(https://example.com/fonts/simple.woff);
3071 /* cross origin, different domain */
3072 /* no Access-Control-xxx headers in response */
3073 src: url(http://another.example.com/fonts/simple.woff);
3074 </pre>
3075 </div>
3077 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3078 Algorithm</h2>
3080 <p>The algorithm below describes how fonts are associated with individual
3081 runs of text. For each character in the run a font family is chosen and a
3082 particular font face is selected containing a glyph for that character.
3084 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3085 font family names</h3>
3087 <p>As part of the font matching algorithm outlined below, user agents must
3088 match font family names used in style rules with actual font family names
3089 contained in fonts available in a given environment or with font family
3090 names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
3091 rules. User agents must match these names case insensitively, using the
3092 "Default Caseless Matching" algorithm outlined in the Unicode
3093 specification <a href="#UNICODE6"
3094 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
3095 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3096 the algorithm must be applied without normalizing the strings involved and
3097 without applying any language-specific tailorings. The case folding method
3098 specified by this algorithm uses the case mappings with status field
3099 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3100 in the CaseFolding.txt file of the Unicode Character Database.
3102 <p class=note> For authors this means that font family names are matched
3103 case insensitively, whether those names exist in a platform font or in the
3104 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3105 in a stylesheet. Authors should take care to ensure that names use a
3106 character sequence consistent with the actual font family name,
3107 particularly when using combining characters such as diacritical marks.
3108 For example, a family name that contains an uppercase A (U+0041) followed
3109 by a combining ring (U+030A) will <strong>not</strong> match a name that
3110 looks identical but which uses the precomposed lowercase a-ring character
3111 (U+00E5) instead of the combining sequence.
3113 <p class=note> Implementors should take care to verify that a given
3114 caseless string comparison implementation uses this precise algorithm and
3115 not assume that a given platform string matching routine follows it, as
3116 many of these have locale-specific behavior or use some level of string
3117 normalization.
3119 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3120 styles</h3>
3122 <p>The procedure for choosing a font for a given character in a run of text
3123 consists of iterating over the font families named by the <a
3124 href="#propdef-font-family" title="font-family!!property">‘<code
3125 class=property>font-family</code>’</a> property, selecting a font face
3126 with the appropriate style based on other font properties and then
3127 determining whether a glyph exists for the given character. This is done
3128 using the <dfn id=character-map>character map</dfn> of the font, data
3129 which maps characters to the default glyph for that character. A font is
3130 considered to <dfn id=support>support</dfn> a given character if (1) the
3131 character is contained in the font's <a
3132 href="#character-map"><em>character map</em></a> and (2) if required by
3133 the containing script, shaping information is available for that
3134 character.
3136 <p>Some legacy fonts may include a given character in the <a
3137 href="#character-map"><em>character map</em></a> but lack the shaping
3138 information (e.g. <a
3139 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3140 layout tables</a> or <a
3141 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3142 tables</a>) necessary for correctly rendering text runs containing that
3143 character.
3145 <p>Codepoint sequences consisting of a base character followed by a
3146 sequence of combining characters are treated slightly differently, see the
3147 section on <a href="#cluster-matching">cluster matching</a> below.
3149 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3150 given font family is defined to be the face that would be selected if all
3151 font style properties were set to their initial value.
3153 <ol id=fontmatchingalg>
3154 <li>Using the computed font property values for a given element, the user
3155 agent starts with the first family name specified by the <a
3156 href="#propdef-font-family" title="font-family!!property">‘<code
3157 class=property>font-family</code>’</a> property.
3159 <li>If the family name is a generic family keyword, the user agent looks
3160 up the appropriate font family name to be used. User agents may choose
3161 the generic font family to use based on the language of the containing
3162 element or the Unicode range of the character.
3164 <li>For other family names, the user agent attempts to find the family
3165 name among fonts defined via <a
3166 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3167 among available system fonts, matching names with a <a
3168 href="#font-family-casing">case-insensitive comparison</a> as outlined in
3169 the section above. On systems containing fonts with multiple localized
3170 font family names, user agents must match any of these names independent
3171 of the underlying system locale or platform API used. If the font
3172 resources defined for a given face in an <a
3173 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3174 available or contain invalid font data, then the face should be treated
3175 as not present in the family. If no faces are present for a family
3176 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3177 rules, the family should be treated as missing; matching a platform font
3178 with the same name must not occur in this case.
3180 <li>If a font family match occurs, the user agent assembles the set of
3181 font faces in that family and then narrows the set to a single face using
3182 other font properties in the order given below. A group of faces defined
3183 via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
3184 identical font descriptor values but differing ‘<a
3185 href="#descdef-unicode-range"><code
3186 class=property>unicode-range</code></a>’ values are considered to be a
3187 single <dfn id=composite-face>composite face</dfn> for this step:
3188 <ol id=fontstylematchingalg>
3189 <li><a href="#propdef-font-stretch"
3190 title="font-stretch!!property">‘<code
3191 class=property>font-stretch</code>’</a> is tried first. If the
3192 matching set contains faces with width values matching the <a
3193 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3194 class=property>font-stretch</code>’</a> value, faces with other width
3195 values are removed from the matching set. If there is no face that
3196 exactly matches the width value the nearest width is used instead. If
3197 the value of <a href="#propdef-font-stretch"
3198 title="font-stretch!!property">‘<code
3199 class=property>font-stretch</code>’</a> is <a
3200 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3201 class=property>normal</code>’</a> or one of the condensed values,
3202 narrower width values are checked first, then wider values. If the
3203 value of <a href="#propdef-font-stretch"
3204 title="font-stretch!!property">‘<code
3205 class=property>font-stretch</code>’</a> is one of the expanded
3206 values, wider values are checked first, followed by narrower values.
3207 Once the closest matching width has been determined by this process,
3208 faces with other widths are removed from the matching set.
3210 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3211 class=property>font-style</code>’</a> is tried next. If the value of
3212 <a href="#propdef-font-style" title="font-style!!property">‘<code
3213 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3214 class=property>italic</code></a>’, italic faces are checked first,
3215 then oblique, then normal faces. If the value is ‘<a
3216 href="#oblique"><code class=property>oblique</code></a>’, oblique
3217 faces are checked first, then italic faces and then normal faces. If
3218 the value is <a href="#font-style-normal-value"
3219 title="normal!!font-style">‘<code
3220 class=property>normal</code>’</a>, normal faces are checked first,
3221 then oblique faces, then italic faces. Faces with other style values
3222 are excluded from the matching set. User agents are permitted to
3223 distinguish between italic and oblique faces within platform font
3224 families but this is not required, so all italic or oblique faces may
3225 be treated as italic faces. However, within font families defined via
3226 <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
3227 and oblique faces must be distinguished using the value of the <a
3228 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3229 class=property>font-style</code>’</a> descriptor. For families that
3230 lack any italic or oblique faces, users agents may create artificial
3231 oblique faces, if this is permitted by the value of the ‘<a
3232 href="#propdef-font-synthesis"><code
3233 class=property>font-synthesis</code></a>’ property.
3235 <li><a href="#propdef-font-weight"
3236 title="font-weight!!property">‘<code
3237 class=property>font-weight</code>’</a> is matched next, so it will
3238 always reduce the matching set to a single font face. If bolder/lighter
3239 relative weights are used, the effective weight is calculated based on
3240 the inherited weight value, as described in the definition of the <a
3241 href="#propdef-font-weight" title="font-weight!!property">‘<code
3242 class=property>font-weight</code>’</a> property. Given the desired
3243 weight and the weights of faces in the matching set after the steps
3244 above, if the desired weight is available that face matches. Otherwise,
3245 a weight is chosen using the rules below:
3246 <ul>
3247 <li>If the desired weight is less than 400, weights below the desired
3248 weight are checked in descending order followed by weights above the
3249 desired weight in ascending order until a match is found.
3251 <li>If the desired weight is greater than 500, weights above the
3252 desired weight are checked in ascending order followed by weights
3253 below the desired weight in descending order until a match is found.
3255 <li>If the desired weight is 400, 500 is checked first and then the
3256 rule for desired weights less than 400 is used.
3258 <li>If the desired weight is 500, 400 is checked first and then the
3259 rule for desired weights less than 400 is used.
3260 </ul>
3262 <li><span class=property>‘<a href="#propdef-font-size"><code
3263 class=property>font-size</code></a>’</span> must be matched within a
3264 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3265 are rounded to the nearest whole pixel, while the tolerance for
3266 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3267 by ‘<code class=property>em</code>’ values in other properties, are
3268 based on the <span class=property>‘<a href="#propdef-font-size"><code
3269 class=property>font-size</code></a>’</span> value that is used, not
3270 the one that is specified.
3271 </ol>
3273 <li>
3274 <p>If the matched face is defined via <a
3275 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
3276 must use the procedure below to select a single font:
3278 <ol>
3279 <li>If the font resource has not been loaded and the range of characters
3280 defined by the ‘<a href="#descdef-unicode-range"><code
3281 class=property>unicode-range</code></a>’ descriptor value includes
3282 the character in question, load the font.
3284 <li>After downloading, if the <a
3285 href="#effective-character-map"><em>effective character map</em></a>
3286 supports the character in question, select that font.
3287 </ol>
3289 <p>When the matched face is a <a href="#composite-face"><em>composite
3290 face</em></a>, user agents must use the procedure above on each of the
3291 faces in the <a href="#composite-face"><em>composite face</em></a> in
3292 reverse order of <a
3293 href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
3295 <p>While the download occurs, user agents may either wait until the font
3296 is downloaded or render once with substituted font metrics and render
3297 again once the font is downloaded.</p>
3299 <li>
3300 <p>If no matching face exists or the matched face does not contain a
3301 glyph for the character to be rendered, the next family name is selected
3302 and the previous three steps repeated. Glyphs from other faces in the
3303 family are not considered. The only exception is that user agents may
3304 optionally substitute a synthetically obliqued version of the <a
3305 href="#default-face"><em>default face</em></a> if that face supports a
3306 given glyph and synthesis of these faces is permitted by the value of
3307 the ‘<a href="#propdef-font-synthesis"><code
3308 class=property>font-synthesis</code></a>’ property. For example, a
3309 synthetic italic version of the regular face may be used if the italic
3310 face doesn't support glyphs for Arabic.</p>
3311 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3314 <li>If there are no more font families to be evaluated and no matching
3315 face has been found, then the user agent performs a <dfn
3316 id=system-font-fallback>system font fallback</dfn> procedure to find the
3317 best match for the character to be rendered. The result of this procedure
3318 may vary across user agents.
3320 <li>If a particular character cannot be displayed using any font, the user
3321 agent should indicate by some means that a character is not being
3322 displayed, displaying either a symbolic representation of the missing
3323 glyph (e.g. using a <a
3324 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3325 Font</a>) or using the missing character glyph from a default font.
3326 </ol>
3328 <p>Optimizations of this process are allowed provided that an
3329 implementation behaves as if the algorithm had been followed exactly.
3330 Matching occurs in a well-defined order to insure that the results are as
3331 consistent as possible across user agents, given an identical set of
3332 available fonts and rendering technology.
3334 <p>The <dfn id=first-available-font>first available font</dfn>, used in the
3335 definition of <a
3336 href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
3337 lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
3338 class=property>ch</code>’, is defined to be the first available font
3339 that would match any character given font families in the ‘<code
3340 class=property>font-family</code>’ list (or a user agent's default font
3341 if none are available).
3343 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3345 <p>When text contains characters such as combining marks, ideally the base
3346 character should be rendered using the same font as the mark, this assures
3347 proper placement of the mark. For this reason, the font matching algorithm
3348 for clusters is more specialized than the general case of matching a
3349 single character by itself. For sequences containing variation selectors,
3350 which indicate the precise glyph to be used for a given character, user
3351 agents always attempt <a href="#system-font-fallback"><em>system font
3352 fallback</em></a> to find the appropriate glyph before using the default
3353 glyph of the base character.
3355 <p>A sequence of codepoints containing combining mark or other modifiers is
3356 termed a grapheme cluster (see <a href="#CSS3TEXT"
3357 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3358 description). For a given cluster containing a base character, <em>b</em>
3359 and a sequence of combining characters <em>c1, c2…</em>, the entire
3360 cluster is matched using these steps:
3362 <ol>
3363 <li>For each family in the font list, a face is chosen using the style
3364 selection rules defined in the previous section.
3365 <ol>
3366 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3367 completely supported by the font, select this font for the sequence.
3369 <li>If a sequence of multiple codepoints is canonically equivalent to a
3370 single character and the font <a href="#support"><em
3371 title=support>supports</em></a> that character, select this font for
3372 the sequence.
3373 </ol>
3375 <li>If no font was found in the font list in step 1:
3376 <ol>
3377 <li>If <em>c1</em> is a variation selector, system fallback must be used
3378 to find a font that <a href="#support"><em
3379 title=support>supports</em></a> the full sequence of <em>b + c1</em>.
3380 If no font on the system <a href="#support"><em
3381 title=support>supports</em></a> the full sequence, match the single
3382 character <em>b</em> using the normal procedure for matching single
3383 characters and ignore the variation selector. Note: a sequence with
3384 more than one variation selector must be treated as an encoding error
3385 and the trailing selectors must be ignored. <a href="#UNICODE6"
3386 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
3388 <li>Otherwise, the user agent may optionally use system font fallback to
3389 match a font that <a href="#support"><em
3390 title=support>supports</em></a> the entire cluster.
3391 </ol>
3393 <li>If no font is found in step 2, use the matching sequence from step 1
3394 to determine the longest sequence that is completely <a
3395 href="#support"><em title=support>supported</em></a> by a font in the
3396 font list and attempt to match the remaining combining characters
3397 separately using the rules for single characters.
3398 </ol>
3400 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3401 issues</h3>
3403 <p>CSS font matching is always performed on text runs containing Unicode
3404 characters, so documents using legacy encodings are assumed to have been
3405 transcoded before matching fonts. For fonts containing <a
3406 href="#character-map"><em title="character map">character maps</em></a>
3407 for both legacy encodings and Unicode, the contents of the legacy encoding
3408 <a href="#character-map"><em>character map</em></a> must have no effect on
3409 the results of the font matching process.
3411 <p>The font matching process does not assume that text runs are in either
3412 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3413 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3414 details). Fonts may only support precomposed forms and not the decomposed
3415 sequence of base character plus combining marks. Authors should always
3416 tailor their choice of fonts to their content, including whether that
3417 content contains normalized or denormalized character streams.
3419 <p>If a given character is a Private-Use Area Unicode codepoint, user
3420 agents must only match font families named in the ‘<code
3421 class=property>font-family</code>’ list that are not generic families.
3422 If none of the families named in the ‘<code
3423 class=property>font-family</code>’ list contain a glyph for that
3424 codepoint, user agents must display some form of missing glyph symbol for
3425 that character rather than attempting <a
3426 href="#system-font-fallback"><em>system font fallback</em></a> for that
3427 codepoint. When matching the replacement character U+FFFD, user agents may
3428 skip the font matching process and immediately display some form of
3429 missing glyph symbol, they are not required to display the glyph from the
3430 font that would be selected by the font matching process.
3432 <p>In general, the fonts for a given family will all have the same or
3433 similar <a href="#character-map"><em title="character map">character
3434 maps</em></a>. The process outlined here is designed to handle even font
3435 families containing faces with widely variant <a href="#character-map"><em
3436 title="character map">character maps</em></a>. However, authors are
3437 cautioned that the use of such families can lead to unexpected results.
3439 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3440 changes since CSS 2.1</h3>
3442 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3443 These changes were made to better reflect actual font matching behavior
3444 across user agent implementations.
3446 <p>Differences compared to the font matching algorithm in CSS 2.1:
3448 <ul>
3449 <li>The algorithm includes font-stretch matching.
3451 <li>All possible font-style matching scenarios are delineated.
3453 <li>Small-caps fonts are not matched as part of the font matching process,
3454 they are now handled via font features.
3456 <li>Unicode variation selector matching is required.
3458 <li>Cluster sequences are matched as a unit.
3459 </ul>
3461 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3462 examples</h3>
3464 <div class=example>
3465 <p>It's useful to note that the CSS selector syntax may be used to create
3466 language-sensitive typography. For example, some Chinese and Japanese
3467 characters are unified to have the same Unicode code point, although the
3468 abstract glyphs are not the same in the two languages.
3470 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3471 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3472 </pre>
3474 <p>This selects any element that has the given language — Japanese or
3475 Traditional Chinese — and uses the appropriate font.
3476 </div>
3478 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3480 <p>Modern font technologies support a variety of advanced typographic and
3481 language-specific font features. Using these features, a single font can
3482 provide glyphs for a wide range of ligatures, contextual and stylistic
3483 alternates, tabular and old-style figures, small capitals, automatic
3484 fractions, swashes, and alternates specific to a given language. To allow
3485 authors control over these font capabilities, the ‘<code
3486 class=property>font-variant</code>’ property has been expanded for CSS3.
3487 It now functions as a shorthand for a set of properties that provide
3488 control over stylistic font features.
3490 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3491 selection and positioning</h3>
3493 <p>Simple fonts used for displaying Latin text use a very basic processing
3494 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3495 which maps each character to a glyph for that character. Glyphs for
3496 subsequent characters are simply placed one after the other along a run of
3497 text. Modern font formats such as OpenType and AAT (Apple Advanced
3498 Typography) use a richer processing model. The glyph for a given character
3499 can be chosen and positioned not just based on the codepoint of the
3500 character itself, but also on adjacent characters as well as the language,
3501 script, and features enabled for the text. Font features may be required
3502 for specific scripts, or recommended as enabled by default or they might
3503 be stylistic features meant to be used under author control.
3505 <p>For a good visual overview of these features, see the <a
3506 href="#OPENTYPE-FONT-GUIDE"
3507 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3508 For a detailed description of glyph processing for OpenType fonts, see <a
3509 href="#WINDOWS-GLYPH-PROC"
3510 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3512 <p>Stylistic font features can be classified into two broad categories:
3513 ones that affect the harmonization of glyph shapes with the surrounding
3514 context, such as kerning and ligature features, and ones such as the
3515 small-caps, subscript/superscript and alternate features that affect shape
3516 selection.
3518 <p>The subproperties of <a href="#propdef-font-variant"
3519 title="font-variant!!property">‘<code
3520 class=property>font-variant</code>’</a> listed below are used to control
3521 these stylistic font features. They do not control features that are
3522 required for displaying certain scripts, such as the OpenType features
3523 used when displaying Arabic or Indic language text. They affect glyph
3524 selection and positioning, but do not affect font selection as described
3525 in the font matching section (except in cases required for compatibility
3526 with CSS 2.1).
3528 <p>To assure consistent behavior across user agents, the equivalent
3529 OpenType property settings are listed for individual properties and are
3530 normative. When using other font formats these should be used as a
3531 guideline to map CSS font feature property values to specific font
3532 features.
3534 <h3 id=language-specific-support><span class=secno>6.2
3535 </span>Language-specific display</h3>
3537 <p>OpenType also supports language-specific glyph selection and
3538 positioning, so that text can be displayed correctly in cases where the
3539 language dictates a specific display behavior. Many languages share a
3540 common script, but the shape of certain letters can vary across those
3541 languages. For example, certain Cyrillic letters have different shapes in
3542 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3543 with an explicit fi-ligature that lacks a dot on the "i". However, in
3544 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3545 important to not use this ligature or use a specialized version that
3546 contains a dot over the "i". The example below shows language-specific
3547 variations based on stylistic traditions found in Spanish, Italian and
3548 French orthography:
3550 <div class=featex><img alt="language specific forms, spanish"
3551 src=locl-1.png></div>
3553 <div class=featex><img alt="language specific forms, italian"
3554 src=locl-2.png></div>
3556 <div class=featex><img alt="language specific forms, french"
3557 src=locl-3.png></div>
3559 <p>If the content language of the element is known according to the rules
3560 of the <a
3561 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3562 language</a>, user agents are required to infer the OpenType language
3563 system from the content language and use that when selecting and
3564 positioning glyphs using an OpenType font.
3566 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3567 declare the OpenType language to be used, for example when displaying text
3568 in a given language that uses the typographic conventions of another
3569 language or when the font does not explicitly support a given language but
3570 supports a language that shares common typographic conventions. The ‘<a
3571 href="#propdef-font-language-override"><code
3572 class=property>font-language-override</code></a>’ property is used for
3573 this purpose.</p>
3574 <!-- prop: font-kerning -->
3576 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3577 href="#propdef-font-kerning">font-kerning</a> property</h3>
3579 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3580 <tbody>
3581 <tr>
3582 <td>Name:
3584 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3586 <tr>
3587 <td>Value:
3589 <td><a href="#font-kerning-auto-value"
3590 title="auto!!font-kerning">auto</a> | <a
3591 href="#font-kerning-normal-value"
3592 title="normal!!font-kerning">normal</a> | <a
3593 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3595 <tr>
3596 <td>Initial:
3598 <td>auto
3600 <tr>
3601 <td>Applies to:
3603 <td>all elements
3605 <tr>
3606 <td>Inherited:
3608 <td>yes
3610 <tr>
3611 <td>Percentages:
3613 <td>N/A
3615 <tr>
3616 <td>Media:
3618 <td>visual
3620 <tr>
3621 <td>Computed value:
3623 <td>as specified
3625 <tr>
3626 <td>Animatable:
3628 <td>no
3629 </table>
3631 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3632 property controls metric kerning, kerning that utilizes adjustment data
3633 contained in the font.
3635 <dl>
3636 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3638 <dd>Specifies that kerning is applied at the discretion of the user agent
3640 <dt><dfn id=font-kerning-normal-value
3641 title="normal!!font-kerning">normal</dfn>
3643 <dd>Specifies that kerning is applied
3645 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3647 <dd>Specifies that kerning is not applied
3648 </dl>
3650 <p>For fonts that do not include kerning data this property will have no
3651 visible effect. When rendering with OpenType fonts, the <a
3652 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3653 specification suggests that kerning be enabled by default. When kerning is
3654 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3655 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3656 instead). User agents must also support fonts that only support kerning
3657 via data contained in a <span class=tag>kern</span> font table, as
3658 detailed in the OpenType specification. If the ‘<code
3659 class=property>letter-spacing</code>’ property is defined, kerning
3660 adjustments are considered part of the default spacing and letter spacing
3661 adjustments are made after kerning has been applied.
3663 <p>When set to ‘<code class=property>auto</code>’, user agents can
3664 determine whether to apply kerning or not based on a number of factors:
3665 text size, script, or other factors that influence text processing speed.
3666 Authors who want proper kerning should use <a
3667 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3668 class=property>normal</code>’</a> to explicitly enable kerning.
3669 Likewise, some authors may prefer to disable kerning in situations where
3670 performance is more important than precise appearance. However, in
3671 well-designed modern implementations the use of kerning generally does not
3672 have a large impact on text rendering speed.</p>
3673 <!-- prop: font-variant-ligatures -->
3675 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3676 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3677 property</h3>
3679 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3680 <tbody>
3681 <tr>
3682 <td>Name:
3684 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3686 <tr>
3687 <td>Value:
3689 <td><a href="#font-variant-ligatures-normal-value"
3690 title="normal!!font-variant-ligatures">normal</a> | <a
3691 href="#font-variant-ligatures-none-value"
3692 title="none!!font-variant-ligatures">none</a> | [ <a
3693 href="#common-lig-values"><var><common-lig-values></var></a> ||
3694 <a
3695 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3696 || <a
3697 href="#historical-lig-values"><var><historical-lig-values></var></a>
3698 || <a
3699 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3700 ]
3702 <tr>
3703 <td>Initial:
3705 <td>normal
3707 <tr>
3708 <td>Applies to:
3710 <td>all elements
3712 <tr>
3713 <td>Inherited:
3715 <td>yes
3717 <tr>
3718 <td>Percentages:
3720 <td>N/A
3722 <tr>
3723 <td>Media:
3725 <td>visual
3727 <tr>
3728 <td>Computed value:
3730 <td>as specified
3732 <tr>
3733 <td>Animatable:
3735 <td>no
3736 </table>
3738 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3739 more harmonized forms.
3741 <pre
3742 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>
3744 <pre
3745 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>
3747 <pre
3748 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>
3750 <pre
3751 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>
3753 <p>Individual values have the following meanings:
3755 <dl>
3756 <dt><dfn id=font-variant-ligatures-normal-value
3757 title="normal!!font-variant-ligatures">normal</dfn>
3759 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3760 title="normal!!font-variant-ligatures">‘<code
3761 class=property>normal</code>’</a> specifies that common default
3762 features are enabled, <a href="#font-feature-resolution">as described in
3763 detail in the next section</a>. For OpenType fonts, common ligatures and
3764 contextual forms are on by default, discretionary and historical
3765 ligatures are not.
3767 <dt><dfn id=font-variant-ligatures-none-value
3768 title="none!!font-variant-ligatures">none</dfn>
3770 <dd>Specifies that all types of ligatures and contextual forms covered by
3771 this property are explicitly disabled. In situations where ligatures are
3772 not considered necessary, this may improve the speed of text rendering.
3774 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3776 <dd>Enables display of common ligatures (OpenType features: <span
3777 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3778 enabled by default.
3779 </dl>
3781 <div class=featex><img alt="common ligature example" src=liga.png></div>
3783 <dl>
3784 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3786 <dd>Disables display of common ligatures (OpenType features: <span
3787 class=tag>liga, clig</span>).
3789 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3791 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3792 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3793 decided by the type designer, so authors will need to refer to the
3794 documentation of a given font to understand which ligatures are
3795 considered discretionary.
3796 </dl>
3798 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3800 <dl>
3801 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3803 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3804 class=tag>dlig</span>).
3806 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3808 <dd>Enables display of historical ligatures (OpenType feature: <span
3809 class=tag>hlig</span>).
3810 </dl>
3812 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3814 <dl>
3815 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3817 <dd>Disables display of historical ligatures (OpenType feature: <span
3818 class=tag>hlig</span>).
3820 <dt><dfn id=contextual>contextual</dfn>
3822 <dd>Enables display of contextual alternates (OpenType feature: <span
3823 class=tag>calt</span>). Although not strictly a ligature feature, like
3824 ligatures this feature is commonly used to harmonize the shapes of glyphs
3825 with the surrounding context. For OpenType fonts, this feature is on by
3826 default.
3827 </dl>
3829 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3831 <dl>
3832 <dt><dfn id=no-contextual>no-contextual</dfn>
3834 <dd>Disables display of contextual alternates (OpenType feature: <span
3835 class=tag>calt</span>).
3836 </dl>
3838 <p>Required ligatures, needed for correctly rendering complex scripts, are
3839 not affected by the settings above, including ‘<code
3840 class=property>none</code>’ (OpenType feature: <span
3841 class=tag>rlig</span>).</p>
3842 <!-- prop: font-variant-position -->
3844 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3845 and superscript forms: the <a
3846 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3848 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3849 <tbody>
3850 <tr>
3851 <td>Name:
3853 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3855 <tr>
3856 <td>Value:
3858 <td><a href="#font-variant-position-normal-value"
3859 title="normal!!font-variant-position">normal</a> | <a
3860 href="#sub">sub</a> | <a href="#super">super</a>
3862 <tr>
3863 <td>Initial:
3865 <td>normal
3867 <tr>
3868 <td>Applies to:
3870 <td>all elements
3872 <tr>
3873 <td>Inherited:
3875 <td>yes
3877 <tr>
3878 <td>Percentages:
3880 <td>N/A
3882 <tr>
3883 <td>Media:
3885 <td>visual
3887 <tr>
3888 <td>Computed value:
3890 <td>as specified
3892 <tr>
3893 <td>Animatable:
3895 <td>no
3896 </table>
3898 <p>This property is used to enable typographic subscript and superscript
3899 glyphs. These are alternate glyphs designed within the same em-box as
3900 default glyphs and are intended to be laid out on the same baseline as the
3901 default glyphs, with no resizing or repositioning of the baseline. They
3902 are explicitly designed to match the surrounding text and to be more
3903 readable without affecting the line height.
3905 <div class=figure><img alt="comparison between real subscript glyphs and
3906 synthesized ones" src=realsubscripts.png>
3907 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3908 (bottom)
3909 </div>
3911 <p>Individual values have the following meanings:
3913 <dl>
3914 <dt><dfn id=font-variant-position-normal-value
3915 title="normal!!font-variant-position">normal</dfn>
3917 <dd>None of the features listed below are enabled.
3919 <dt><dfn id=sub>sub</dfn>
3921 <dd>Enables display of subscript variants (OpenType feature: <span
3922 class=tag>subs</span>).
3924 <dt><dfn id=super>super</dfn>
3926 <dd>Enables display of superscript variants (OpenType feature: <span
3927 class=tag>sups</span>).
3928 </dl>
3930 <p>Because of the semantic nature of subscripts and superscripts, when the
3931 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3932 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3933 given contiguous run of text, if a variant glyph is not available for all
3934 the characters in the run, simulated glyphs must be synthesized for all
3935 characters using reduced forms of the glyphs that would be used without
3936 this feature applied. This is done per run to avoid a mixture of variant
3937 glyphs and synthesized ones that would not align correctly. In the case of
3938 OpenType fonts that lack subscript or superscript glyphs for a given
3939 character, user agents must use the appropriate subscript and superscript
3940 metrics specified in the selected font's <a
3941 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3942 table</a> <a href="#OPENTYPE"
3943 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3944 and offset of the synthesized substitutes.
3946 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3947 using superscript metrics" src=superscript-alt-synth.png>
3948 <p class=caption>Superscript alternate glyph (left), synthesized
3949 superscript glyphs (middle), and incorrect mixture of the two (right)
3950 </div>
3952 <p>In situations where text decorations are only applied to runs of text
3953 containing superscript or subscript glyphs, the synthesized glyphs must be
3954 used to avoid problems with the placement of decorations.
3956 <p>In the past, user agents have used font-size and vertical-align to
3957 simulate subscripts and superscripts for the <code title="HTML sub
3958 element">sub</code> and <code title="HTML sup element">sup</code>
3959 elements. To allow a backwards compatible way of defining subscripts and
3960 superscripts, it is recommended that authors use conditional rules <a
3961 href="#CSS3-CONDITIONAL"
3962 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3963 older user agents will still render subscripts and superscripts via the
3964 older mechanism.
3966 <p>Authors should note that fonts typically only provide subscript and
3967 superscript glyphs for a subset of all characters supported by the font.
3968 For example, while subscript and superscript glyphs are often available
3969 for Latin numbers, glyphs for punctuation and letter characters are less
3970 frequently provided. The synthetic fallback rules defined for this
3971 property assure that subscripts and superscripts will always appear but
3972 the appearance may not match author expectations if the font used does not
3973 provide the appropriate alternate glyph for all characters contained in a
3974 subscript or superscript.
3976 <p>This property is not cumulative. Applying it to elements within a
3977 subscript or superscript won't nest the placement of a subscript or
3978 superscript glyph. Images contained within text runs where the value of
3979 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3980 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3981 drawn just as they would if the value was <a
3982 href="#font-variant-position-normal-value"
3983 title="normal!!font-variant-position">‘<code
3984 class=property>normal</code>’</a>.</p>
3985 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
3986 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
3988 <p>Because of these limitations, ‘<a
3989 href="#propdef-font-variant-position"><code
3990 class=property>font-variant-position</code></a>’ is not recommended for
3991 use in user agent stylesheets. Authors should use it in cases where
3992 subscripts or superscripts will only contain the narrow range of
3993 characters supported by the fonts specified.
3995 <p class=note>The variant glyphs use the same baseline as the default
3996 glyphs would use. There is no shift in the placement along the baseline,
3997 so the use of variant glyphs doesn't affect the height of the inline box
3998 or alter the height of the linebox. This makes superscript and subscript
3999 variants ideal for situations where it's important that leading remain
4000 constant, such as in multi-column layout.
4002 <div class=example>
4003 <p>A typical user agent default style for the <a class=tag
4004 href="#sub">sub</a> element:</p>
4006 <pre>sub {
4007 vertical-align: sub;
4008 font-size: smaller;
4009 line-height: normal;
4010 }
4011 </pre>
4013 <p>Using font-variant-position to specify typographic subscripts in a way
4014 that will still show subscripts in older user agents:</p>
4016 <pre>@supports ( font-variant-position: sub ) {
4018 sub {
4019 vertical-align: baseline;
4020 font-size: 100%;
4021 line-height: inherit;
4022 font-variant-position: sub;
4023 }
4025 }
4026 </pre>
4028 <p>User agents that support the ‘<a
4029 href="#propdef-font-variant-position"><code
4030 class=property>font-variant-position</code></a>’ property will select a
4031 subscript variant glyph and render this without adjusting the baseline or
4032 font-size. Older user agents will ignore the ‘<a
4033 href="#propdef-font-variant-position"><code
4034 class=property>font-variant-position</code></a>’ property definition
4035 and use the standard defaults for subscripts.</p>
4036 </div>
4037 <!-- prop: font-variant-caps -->
4039 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4040 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4042 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4043 <tbody>
4044 <tr>
4045 <td>Name:
4047 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4049 <tr>
4050 <td>Value:
4052 <td><a href="#font-variant-caps-normal-value"
4053 title="normal!!font-variant-caps">normal</a> | <a
4054 href="#small-caps">small-caps</a> | <a
4055 href="#all-small-caps">all-small-caps</a> | <a
4056 href="#petite-caps">petite-caps</a> | <a
4057 href="#all-petite-caps">all-petite-caps</a> | <a
4058 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4060 <tr>
4061 <td>Initial:
4063 <td>normal
4065 <tr>
4066 <td>Applies to:
4068 <td>all elements
4070 <tr>
4071 <td>Inherited:
4073 <td>yes
4075 <tr>
4076 <td>Percentages:
4078 <td>N/A
4080 <tr>
4081 <td>Media:
4083 <td>visual
4085 <tr>
4086 <td>Computed value:
4088 <td>as specified
4090 <tr>
4091 <td>Animatable:
4093 <td>no
4094 </table>
4096 <p>This property allows the selection of alternate glyphs used for small or
4097 petite capitals or for titling. These glyphs are specifically designed to
4098 blend well with the surrounding normal glyphs, to maintain the weight and
4099 readability which suffers when text is simply resized to fit this purpose.
4101 <p>Individual values have the following meanings:
4103 <dl>
4104 <dt><dfn id=font-variant-caps-normal-value
4105 title="normal!!font-variant-caps">normal</dfn>
4107 <dd>None of the features listed below are enabled.
4109 <dt><dfn id=small-caps>small-caps</dfn>
4111 <dd>Enables display of small capitals (OpenType feature: <span
4112 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4113 uppercase letters but are reduced to the size of lowercase letters.
4114 </dl>
4116 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4118 <dl>
4119 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4121 <dd>Enables display of small capitals for both upper and lowercase letters
4122 (OpenType features: <span class=tag>c2sc, smcp</span>).
4124 <dt><dfn id=petite-caps>petite-caps</dfn>
4126 <dd>Enables display of petite capitals (OpenType feature: <span
4127 class=tag>pcap</span>).
4129 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4131 <dd>Enables display of petite capitals for both upper and lowercase
4132 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4134 <dt><dfn id=unicase>unicase</dfn>
4136 <dd>Enables display of mixture of small capitals for uppercase letters
4137 with normal lowercase letters (OpenType feature: <span
4138 class=tag>unic</span>).
4140 <dt><dfn id=titling-caps>titling-caps</dfn>
4142 <dd>Enables display of titling capitals (OpenType feature: <span
4143 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4144 use with lowercase letters. When used in all uppercase titling sequences
4145 they can appear too strong. Titling capitals are designed specifically
4146 for this situation.
4147 </dl>
4149 <p>The availability of these glyphs is based on whether a given feature is
4150 defined or not in the feature list of the font. User agents can optionally
4151 decide this on a per-script basis but should explicitly not decide this on
4152 a per-character basis.
4154 <p>Some fonts may only support a subset or none of the features described
4155 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4156 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4157 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4158 is specified but small-caps glyphs are not available for a given font,
4159 user agents should simulate a small-caps font, for example by taking a
4160 normal font and replacing the glyphs for lowercase letters with scaled
4161 versions of the glyphs for uppercase characters (replacing the glyphs for
4162 both upper and lowercase letters in the case of ‘<a
4163 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4165 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4166 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4167 width=512>
4168 <p class=caption>Synthetic vs. real small-caps
4169 </div>
4171 <p>To match the surrounding text, a font may provide alternate glyphs for
4172 caseless characters when these features are enabled but when a user agent
4173 simulates small capitals, it must not attempt to simulate alternates for
4174 codepoints which are considered caseless.
4176 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4177 characters with small-caps, all-small-caps enabled" class=hires
4178 src=small-capitals-variations.png width=418>
4179 <p class=caption>Caseless characters with small-caps, all-small-caps
4180 enabled
4181 </div>
4183 <p>If either ‘<a href="#petite-caps"><code
4184 class=property>petite-caps</code></a>’ or ‘<a
4185 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4186 is specified for a font that doesn't support these features, the property
4187 behaves as if ‘<a href="#small-caps"><code
4188 class=property>small-caps</code></a>’ or ‘<a
4189 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4190 respectively, had been specified. If ‘<a href="#unicase"><code
4191 class=property>unicase</code></a>’ is specified for a font that doesn't
4192 support that feature, the property behaves as if ‘<a
4193 href="#small-caps"><code class=property>small-caps</code></a>’ was
4194 applied only to lowercased uppercase letters. If ‘<a
4195 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4196 specified with a font that does not support this feature, this property
4197 has no visible effect. When simulated small capital glyphs are used, for
4198 scripts that lack uppercase and lowercase letters, ‘<a
4199 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4200 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4201 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4202 ‘<a href="#all-petite-caps"><code
4203 class=property>all-petite-caps</code></a>’ and ‘<a
4204 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4205 effect.
4207 <p>When casing transforms are used to simulate small capitals, the casing
4208 transformations must match those used for the <span
4209 class=property>‘<code class=property>text-transform</code>’</span>
4210 property.
4212 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4213 replace glyphs in a small-caps font so that the text appears in all
4214 uppercase letters.
4216 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4217 all-small-caps in acronym-laden text" class=hires
4218 src=acronym-laden-text.png width=596>
4219 <p class=caption>Using small capitals to improve readability in
4220 acronym-laden text
4221 </div>
4223 <div class=example>
4224 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4226 <pre>blockquote { font-style: italic; }
4227 blockquote:first-line { font-variant: small-caps; }
4229 <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>
4230 </pre>
4231 </div>
4232 <!-- prop: font-variant-numeric -->
4234 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4235 formatting: the <a
4236 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4238 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4239 <tbody>
4240 <tr>
4241 <td>Name:
4243 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4245 <tr>
4246 <td>Value:
4248 <td><a href="#font-variant-numeric-normal-value"
4249 title="normal!!font-variant-numeric">normal</a> | [ <a
4250 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4251 || <a
4252 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4253 || <a
4254 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4255 || <a href="#ordinal">ordinal</a> || <a
4256 href="#slashed-zero">slashed-zero</a> ]
4258 <tr>
4259 <td>Initial:
4261 <td>normal
4263 <tr>
4264 <td>Applies to:
4266 <td>all elements
4268 <tr>
4269 <td>Inherited:
4271 <td>yes
4273 <tr>
4274 <td>Percentages:
4276 <td>N/A
4278 <tr>
4279 <td>Media:
4281 <td>visual
4283 <tr>
4284 <td>Computed value:
4286 <td>as specified
4288 <tr>
4289 <td>Animatable:
4291 <td>no
4292 </table>
4294 <p>Specifies control over numerical forms. The example below shows how some
4295 of these values can be combined to influence the rendering of tabular data
4296 with fonts that support these features. Within normal paragraph text,
4297 proportional numbers are used while tabular numbers are used so that
4298 columns of numbers line up properly:
4300 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4301 number styles" src=numberstyles.png>
4302 <p class=caption>Using number styles
4303 </div>
4305 <p>Possible combinations:
4307 <pre
4308 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>
4310 <pre
4311 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>
4313 <pre
4314 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>
4316 <p>Individual values have the following meanings:
4318 <dl>
4319 <dt><dfn id=font-variant-numeric-normal-value
4320 title="normal!!font-variant-numeric">normal</dfn>
4322 <dd>None of the features listed below are enabled.
4324 <dt><dfn id=lining-nums>lining-nums</dfn>
4326 <dd>Enables display of lining numerals (OpenType feature: <span
4327 class=tag>lnum</span>).
4329 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4331 <dd>Enables display of old-style numerals (OpenType feature: <span
4332 class=tag>onum</span>).
4334 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4336 <dd>Enables display of proportional numerals (OpenType feature: <span
4337 class=tag>pnum</span>).
4339 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4341 <dd>Enables display of tabular numerals (OpenType feature: <span
4342 class=tag>tnum</span>).
4344 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4346 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4347 class=tag>frac</span>).
4348 </dl>
4350 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4352 <dl>
4353 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4355 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4356 class=tag>afrc</span>).
4357 </dl>
4359 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4361 <dl>
4362 <dt><dfn id=ordinal>ordinal</dfn>
4364 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4365 <span class=tag>ordn</span>).
4367 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4369 <dd>Enables display of slashed zeros (OpenType feature: <span
4370 class=tag>zero</span>).
4371 </dl>
4373 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4375 <div class=example id=steak-marinade>
4376 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4377 and old-style numerals:</p>
4379 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4381 <h4>Steak marinade:</h4>
4382 <ul>
4383 <li><span class="amount">2</span> tbsp olive oil</li>
4384 <li><span class="amount">1</span> tbsp lemon juice</li>
4385 <li><span class="amount">1</span> tbsp soy sauce</li>
4386 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4387 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4388 <li>Salt &amp; pepper</li>
4389 </ul>
4391 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4392 for a few hours or overnight.</p>
4393 </pre>
4395 <p>Note that the fraction feature is only applied to values not the entire
4396 paragraph. Fonts often implement this feature using contextual rules
4397 based on the use of the slash (‘<code class=css>/</code>’) character.
4398 As such, it's not suitable for use as a paragraph-level style.</p>
4399 </div>
4400 <!-- prop: font-variant-alternates -->
4402 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4403 and swashes: the <a
4404 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4405 property</h3>
4407 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4408 <tbody>
4409 <tr>
4410 <td>Name:
4412 <td><dfn
4413 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4415 <tr>
4416 <td>Value:
4418 <td>normal | [ <a href="#stylistic"
4419 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4420 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4421 title=styleset>styleset(<feature-value-name> #)</a> || <a
4422 href="#character-variant"
4423 title=character-variant>character-variant(<feature-value-name>
4424 #)</a> || <a href="#swash"
4425 title=swash>swash(<feature-value-name>)</a> || <a
4426 href="#ornaments"
4427 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4428 href="#annotation"
4429 title=annotation>annotation(<feature-value-name>)</a> ]
4431 <tr>
4432 <td>Initial:
4434 <td>normal
4436 <tr>
4437 <td>Applies to:
4439 <td>all elements
4441 <tr>
4442 <td>Inherited:
4444 <td>yes
4446 <tr>
4447 <td>Percentages:
4449 <td>N/A
4451 <tr>
4452 <td>Media:
4454 <td>visual
4456 <tr>
4457 <td>Computed value:
4459 <td>as specified
4461 <tr>
4462 <td>Animatable:
4464 <td>no
4465 </table>
4467 <p>For any given character, fonts can provide a variety of alternate glyphs
4468 in addition to the default glyph for that character. This property
4469 provides control over the selection of these alternate glyphs.
4471 <p>For many of the property values listed below, several different
4472 alternate glyphs are available. How many alternates are available and what
4473 they represent is font-specific, so these are each marked <dfn
4474 id=font-specific>font specific</dfn> in the value definitions below.
4475 Because the nature of these alternates is font-specific, the <a
4476 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4477 rule is used to define values for a specific font family or set of
4478 families that associate a font-specific numeric
4479 <code><feature-index></code> with a custom
4480 <code><feature-value-name></code>, which is then used in this
4481 property to select specific alternates:
4483 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4485 p {
4486 font-family: Noble Script;
4487 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4488 }</pre>
4490 <p>When a particular <code><feature-value-name></code> has not been
4491 defined for a given family or for a particular feature type, the computed
4492 value must be the same as if it had been defined. However, property values
4493 that contain these undefined <code><feature-value-name></code>
4494 identifiers must be ignored when choosing glyphs.
4496 <pre>/* these two style rules are effectively the same */
4497 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4498 p { font-variant-alternates: normal; }
4499 </pre>
4501 <p>This allows values to be defined and used for a given set of font
4502 families but ignored if fallback occurs, since the font family name would
4503 be different. If a given value is outside the range supported by a given
4504 font, the value is ignored. These values never apply to generic font
4505 families.
4507 <p>Individual values have the following meanings:
4509 <dl>
4510 <dt><dfn id=font-variant-alternates-normal-value
4511 title="normal!!font-variant-alternates">normal</dfn>
4513 <dd>None of the features listed below are enabled.
4515 <dt><dfn id=historical-forms>historical-forms</dfn>
4517 <dd>Enables display of historical forms (OpenType feature: <span
4518 class=tag>hist</span>).
4519 </dl>
4521 <div class=featex><img alt="historical form example" src=hist.png></div>
4523 <dl>
4524 <dt><dfn id=stylistic
4525 title=stylistic>stylistic(<feature-value-name>)</dfn>
4527 <dd>Enables display of stylistic alternates (<a
4528 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4529 class=tag>salt <feature-index></span>).
4530 </dl>
4532 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4534 <dl>
4535 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4536 #)</dfn>
4538 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4539 specific</em></a>, OpenType feature: <span
4540 class=tag>ss<feature-index></span> OpenType currently defines <span
4541 class=tag>ss01</span> through <span class=tag>ss20</span>).
4542 </dl>
4544 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4546 <dl>
4547 <dt><dfn id=character-variant
4548 title=character-variant>character-variant(<feature-value-name>
4549 #)</dfn>
4551 <dd>Enables display of specific character variants (<a
4552 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4553 class=tag>cv<feature-index></span> OpenType currently defines <span
4554 class=tag>cv01</span> through <span class=tag>cv99</span>).
4556 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4558 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4559 specific</em></a>, OpenType feature: <span class=tag>swsh
4560 <feature-index>, cswh <feature-index></span>).
4561 </dl>
4563 <div class=featex><img alt="swash example" src=swsh.png></div>
4565 <dl>
4566 <dt><dfn id=ornaments
4567 title=ornaments>ornaments(<feature-value-name>)</dfn>
4569 <dd>Enables replacement of default glyphs with ornaments, if provided in
4570 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4571 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4572 may offer ornament glyphs as alternates for a wide collection of
4573 characters; however, displaying arbitrary characters (e.g.,
4574 alphanumerics) as ornaments is poor practice as it distorts the semantics
4575 of the data. Font designers are encouraged to encode all ornaments
4576 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4577 alternates for the bullet character (U+2022) to allow authors to select
4578 the desired glyph using ‘<a href="#ornaments"><code
4579 class=property>ornaments</code></a>’.
4580 </dl>
4582 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4584 <dl>
4585 <dt><dfn id=annotation
4586 title=annotation>annotation(<feature-value-name>)</dfn>
4588 <dd>Enables display of alternate annotation forms (<a
4589 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4590 class=tag>nalt <feature-index></span>).
4591 </dl>
4593 <div class=featex><img alt="alternate annotation form example"
4594 src=nalt.png></div>
4596 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4597 specific alternates: the <dfn id=at-font-feature-values-rule
4598 style="font-weight: inherit; font-style:
4599 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4601 <p>Several of the possible values of ‘<a
4602 href="#propdef-font-variant-alternates"><code
4603 class=property>font-variant-alternates</code></a>’ listed above are
4604 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4605 features fonts may define not just a single glyph but a set of alternate
4606 glyphs with an index to select a given alternate. Since these are font
4607 family specific, the <a
4608 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4609 rule is used to define named values for these indices for a given family.
4611 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4612 reference section</a> for a description of the interfaces used to modify
4613 these rules via the CSS Object Model.
4615 <div class=example>
4616 <p>In the case of the swash Q in the example shown above, the swash could
4617 be specified using these style rules:</p>
4619 <pre>
4621 @font-feature-values Jupiter Sans {
4622 @swash {
4623 delicate: 1;
4624 flowing: 2;
4625 }
4626 }
4628 h2 { font-family: Jupiter Sans, sans-serif; }
4630 /* show the second swash variant in h2 headings */
4631 h2:first-letter { font-variant-alternates: swash(flowing); }
4633 <h2>Quick</h2></pre>
4635 <p>When Jupiter Sans is present, the second alternate swash alternate will
4636 be displayed. When not present, no swash character will be shown, since
4637 the specific named value "flowing" is only defined for the Jupiter Sans
4638 family. The @-mark indicates the name of the property value for which a
4639 named value can be used. The name "flowing" is chosen by the author. The
4640 index that represents each alternate is defined within a given font's
4641 data.</p>
4642 </div>
4644 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4646 <p>An <a
4647 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4648 rule is composed of a list of font families followed by a block containing
4649 individual <a href="#featurevalueblock"><i
4650 title="feature_value_block">feature value blocks</i></a> that take the
4651 form of @-rules. Each block defines a set of named values for a specific
4652 font feature when a given set of font families is used. Effectively, they
4653 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4654 ⟨values⟩ are the numeric indices used for specific features defined
4655 for a given font.
4657 <p>In terms of the grammar, this specification defines the following
4658 productions:
4660 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4661 : <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>*
4662 '{' <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>*
4663 ;
4665 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4666 : <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> ]*
4667 ;
4669 <dfn id=fontfamilyname>font_family_name</dfn>
4670 : <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> ]* ]
4671 ;
4673 <dfn id=featurevalueblock>feature_value_block</dfn>
4674 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4675 '{' <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>*
4676 ;
4678 <dfn id=featuretype>feature_type</dfn>:
4679 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4680 ;
4682 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4683 : <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> ]*
4684 ;
4685 </pre>
4687 <p>The following new token is introduced:
4689 <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>;}
4690 </pre>
4692 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4693 value blocks</i></a> are handled as <a
4694 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4695 consist of everything up to the next block or semi-colon, whichever comes
4696 first.
4698 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4699 family list</i></a> is a comma-delimited list of <a
4700 href="#fontfamilyname"><i title="font_family_name">font family
4701 names</i></a> that match the definition of <a
4702 href="#family-name-value"><var><family-name></var></a> for the <a
4703 href="#propdef-font-family" title="font-family!!property">‘<code
4704 class=property>font-family</code>’</a> property. This means that only
4705 named font families are allowed, rules that include generic or system
4706 fonts in the list of font families are syntax errors. However, if a user
4707 agent defines a generic font to be a specific named font (e.g. Helvetica),
4708 the settings associated with that family name will be used. If syntax
4709 errors occur within the font family list, the entire rule must be ignored.
4711 <p>Within <a href="#featurevalueblock"><i
4712 title="feature_value_block">feature value blocks</i></a>, the <a
4713 href="#featuretype"><i title="feature_type">feature type</i></a> is
4714 ‘<code class=css>@</code>’ followed by the name of one of the <a
4715 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4716 href="#propdef-font-variant-alternates"><code
4717 class=property>font-variant-alternates</code></a>’ (e.g. <a
4718 href="#swash"><code>@swash</code></a>). The identifiers used within
4719 feature value definitions follow the rules of CSS user identifiers and are
4720 case-sensitive. They are unique only for a given set of font families and
4721 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4722 same identifier used with a different <a href="#featuretype"><i
4723 title="feature_type">feature type</i></a> is treated as a separate and
4724 distinct value. If the same identifier is defined mulitple times for a
4725 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4726 and font family, the last defined value is used. Values associated with a
4727 given identifier are limited to integer values 0 or greater.
4729 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4730 title="feature_value_definition">feature value definition</i></a>, such as
4731 invalid identifiers or values, the entire <a
4732 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4733 value definition</i></a> must be omitted, just as syntax errors in style
4734 declarations are handled. When the <a href="#featuretype"><i
4735 title="feature_type">feature type</i></a> is invalid, the entire
4736 associated <a href="#featurevalueblock"><i
4737 title="feature_value_block">feature value block</i></a> must be ignored.
4739 <div class=example>
4740 <p>Rules that are equivalent given syntax error handling:</p>
4742 <pre>@font-feature-values Bongo {
4743 @swash { ornate: 1; }
4744 annotation { boxed: 4; } /* should be @annotation! */
4745 @swash { double-loops: 1; flowing: -1; } /* negative value */
4746 @ornaments ; /* incomplete definition */
4747 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4748 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4749 }</pre>
4751 <p>The example above is equivalent to:</p>
4753 <pre>@font-feature-values Bongo {
4754 @swash { ornate: 1; }
4755 @swash { double-loops: 1; }
4756 @styleset { double-W: 14; sharp-terminals: 16 1; }
4757 }</pre>
4758 </div>
4760 <p>If multiple <a
4761 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4762 rules are defined for a given family, the resulting values definitions are
4763 the union of the definitions contained within these rules. This allows a
4764 set of named values to be defined for a given font family globally for a
4765 site and specific additions made per-page.
4767 <div class=example>
4768 <p>Using both site-wide and per-page feature values:</p>
4770 <pre>
4771 site.css:
4773 @font-feature-values Mercury Serif {
4774 @styleset {
4775 stacked-g: 3; /* "two-storey" versions of g, a */
4776 stacked-a: 4;
4777 }
4778 }
4780 page.css:
4782 @font-feature-values Mercury Serif {
4783 @styleset {
4784 geometric-m: 7; /* alternate version of m */
4785 }
4786 }
4788 body {
4789 font-family: Mercury Serif, serif;
4791 /* enable both the use of stacked g and alternate m */
4792 font-variant-alternates: styleset(stacked-g, geometric-m);
4793 }</pre>
4794 </div>
4796 <div class=example>
4797 <p>Using a commonly named value allows authors to use a single style rule
4798 to cover a set of fonts for which the underlying selector is different
4799 for each font. If either font in the example below is found, a circled
4800 number glyph will be used:</p>
4802 <pre>@font-feature-values Taisho Gothic {
4803 @annotation { boxed: 1; circled: 4; }
4804 }
4806 @font-feature-values Otaru Kisa {
4807 @annotation { circled: 1; black-boxed: 3; }
4808 }
4810 h3.title {
4811 /* circled form defined for both fonts */
4812 font-family: Taisho Gothic, Otaru Kisa;
4813 font-variant: annotation(circled);
4814 }</pre>
4815 </div>
4817 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4818 </span>Multi-valued feature value definitions</h4>
4820 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4821 href="#propdef-font-variant-alternates"><code
4822 class=property>font-variant-alternates</code></a>’ property values take
4823 a single value (e.g. ‘<a href="#swash"><code
4824 class=property>swash</code></a>’). The ‘<a
4825 href="#character-variant"><code
4826 class=property>character-variant</code></a>’ property value allows two
4827 values and ‘<a href="#styleset"><code
4828 class=property>styleset</code></a>’ allows an unlimited number.
4830 <p>For the styleset property value, multiple values indicate the style sets
4831 to be enabled. Values between 1 and 99 enable OpenType features <span
4832 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4833 OpenType standard only officially defines <span class=tag>ss01</span>
4834 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4835 than 99 or equal to 0 do not generate a syntax error when parsed but
4836 enable no OpenType features.
4838 <pre>@font-feature-values Mars Serif {
4839 @styleset {
4840 alt-g: 1; /* implies ss01 = 1 */
4841 curly-quotes: 3; /* implies ss03 = 1 */
4842 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4843 }
4845 @styleset {
4846 dumb: 125; /* >99, ignored */
4847 }
4849 @swash {
4850 swishy: 3 5; /* more than 1 value for swash, syntax error */
4851 }
4852 }
4854 p.codeblock {
4855 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4856 font-variant-alternates: styleset(curly-quotes, code);
4857 }</pre>
4859 <p>For character-variant, a single value between 1 and 99 indicates the
4860 enabling of OpenType feature <span class=tag>cv01</span> through <span
4861 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4862 to 0 are ignored but do not generate a syntax error when parsed but enable
4863 no OpenType features. When two values are listed, the first value
4864 indicates the feature used and the second the value passed for that
4865 feature. If more than two values are assigned to a given name, a syntax
4866 error occurs and the entire <a href="#featurevaluedefinition"><i
4867 title="feature_value_definition">feature value definition</i></a> is
4868 ignored.
4870 <pre>@font-feature-values MM Greek {
4871 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4872 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4873 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4874 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4875 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4876 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4877 @character-variant { silly: 105; } /* >99, ignored */
4878 @character-variant { dumb: 323 3; } /* >99, ignored */
4879 }
4881 #title {
4882 /* use the third alternate beta, first alternate gamma */
4883 font-variant-alternates: character-variant(beta-3, gamma);
4884 }
4886 p {
4887 /* zeta-2 follows zeta, implies cv20 = 2 */
4888 font-variant-alternates: character-variant(zeta, zeta-2);
4889 }
4891 .special {
4892 /* zeta follows zeta-2, implies cv20 = 3 */
4893 font-variant-alternates: character-variant(zeta-2, zeta);
4894 }</pre>
4896 <div class=figure><img alt="Matching text on Byzantine seals using
4897 character variants" src=byzantineseal.png>
4898 <p class=caption>Byzantine seal text displayed with character variants
4899 </div>
4901 <div class=example>
4902 <p>In the figure above, the text in red is rendered using a font
4903 containing character variants that mimic the character forms found on a
4904 Byzantine seal from the 8th century A.D. Two lines below is the same text
4905 displayed in a font without variants. Note the two variants for U and N
4906 used on the seal.</p>
4908 <pre>@font-feature-values Athena Ruby {
4909 @character-variant {
4910 leo-B: 2 1;
4911 leo-M: 13 3;
4912 leo-alt-N: 14 1;
4913 leo-N: 14 2;
4914 leo-T: 20 1;
4915 leo-U: 21 2;
4916 leo-alt-U: 21 4;
4917 }
4918 }
4920 p {
4921 font-variant: discretionary-ligatures,
4922 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4923 }
4925 span.alt-N {
4926 font-variant-alternates: character-variant(leo-alt-N);
4927 }
4929 span.alt-U {
4930 font-variant-alternates: character-variant(leo-alt-U);
4931 }
4933 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4935 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4936 </pre>
4937 </div>
4939 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4940 Asian text rendering: the <a
4941 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4942 property</h3>
4944 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4945 <tbody>
4946 <tr>
4947 <td>Name:
4949 <td><dfn
4950 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4952 <tr>
4953 <td>Value:
4955 <td><a href="#font-variant-east-asian-normal-value"
4956 title="normal!!font-variant-east-asian">normal</a> | [ <a
4957 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4958 || <a
4959 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4960 || <a href="#ruby">ruby</a> ]
4962 <tr>
4963 <td>Initial:
4965 <td>normal
4967 <tr>
4968 <td>Applies to:
4970 <td>all elements
4972 <tr>
4973 <td>Inherited:
4975 <td>yes
4977 <tr>
4978 <td>Percentages:
4980 <td>N/A
4982 <tr>
4983 <td>Media:
4985 <td>visual
4987 <tr>
4988 <td>Computed value:
4990 <td>as specified
4992 <tr>
4993 <td>Animatable:
4995 <td>no
4996 </table>
4998 <p>Allows control of glyph substitution and sizing in East Asian text.
5000 <pre
5001 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>
5003 <pre
5004 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>
5006 <p>Individual values have the following meanings:
5008 <dl>
5009 <dt><dfn id=font-variant-east-asian-normal-value
5010 title="normal!!font-variant-east-asian">normal</dfn>
5012 <dd>None of the features listed below are enabled.
5014 <dt><dfn id=jis78>jis78</dfn>
5016 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
5017 class=tag>jp78</span>).
5018 </dl>
5020 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
5022 <dl>
5023 <dt><dfn id=jis83>jis83</dfn>
5025 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
5026 class=tag>jp83</span>).
5028 <dt><dfn id=jis90>jis90</dfn>
5030 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
5031 class=tag>jp90</span>).
5033 <dt><dfn id=jis04>jis04</dfn>
5035 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5036 class=tag>jp04</span>).
5037 <p>The various JIS variants reflect the glyph forms defined in different
5038 Japanese national standards. Fonts generally include glyphs defined by
5039 the most recent national standard but it's sometimes necessary to use
5040 older variants, to match signage for example.</p>
5042 <dt><dfn id=simplified>simplified</dfn>
5044 <dd>Enables rendering of simplified forms (OpenType feature: <span
5045 class=tag>smpl</span>).
5047 <dt><dfn id=traditional>traditional</dfn>
5049 <dd>Enables rendering of traditional forms (OpenType feature: <span
5050 class=tag>trad</span>).
5051 </dl>
5053 <p>The ‘<a href="#simplified"><code
5054 class=property>simplified</code></a>’ and ‘<a
5055 href="#traditional"><code class=property>traditional</code></a>’ values
5056 allow control over the glyph forms for characters which have been
5057 simplified over time but for which the older, traditional form is still
5058 used in some contexts. The exact set of characters and glyph forms will
5059 vary to some degree by context for which a given font was designed.
5061 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5063 <dl>
5064 <dt><dfn id=full-width>full-width</dfn>
5066 <dd>Enables rendering of full-width variants (OpenType feature: <span
5067 class=tag>fwid</span>).
5069 <dt><dfn id=proportional-width>proportional-width</dfn>
5071 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5072 <span class=tag>pwid</span>).
5073 </dl>
5075 <div class=featex><img alt="proportionally spaced Japanese example"
5076 src=pwid.png></div>
5078 <dl>
5079 <dt><dfn id=ruby>ruby</dfn>
5081 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5082 class=tag>ruby</span>). Since ruby text is generally smaller than the
5083 associated body text, font designers can design special glyphs for use
5084 with ruby that are more readable than scaled down versions of the default
5085 glyphs. Only glyph selection is affected, there is no associated font
5086 scaling or other change that affects line layout. The red ruby text below
5087 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5088 Note the slight difference in stroke thickness.
5089 </dl>
5091 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5093 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5094 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5095 property</h3>
5097 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5098 <tbody>
5099 <tr>
5100 <td>Name:
5102 <td><dfn id=propdef-font-variant
5103 title="font-variant!!property">font-variant</dfn>
5105 <tr>
5106 <td>Value:
5108 <td><a href="#font-variant-normal-value"
5109 title="normal!!font-variant">normal</a> | <a
5110 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5111 <a href="#common-lig-values"><var><common-lig-values></var></a>
5112 || <a
5113 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5114 || <a
5115 href="#historical-lig-values"><var><historical-lig-values></var></a>
5116 || <a
5117 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5118 || <a href="#stylistic"><var
5119 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5120 href="#historical-forms"><var>historical-forms</var></a> || <a
5121 href="#styleset"><var
5122 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5123 href="#character-variant"><var
5124 title=character-variant>character-variant(<feature-value-name>
5125 #)</var></a> || <a href="#swash"><var
5126 title=swash>swash(<feature-value-name>)</var></a> || <a
5127 href="#ornaments"><var
5128 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5129 href="#annotation"><var
5130 title=annotation>annotation(<feature-value-name>)</var></a> || [
5131 <a href="#small-caps"><i>small-caps</i></a> | <a
5132 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5133 href="#petite-caps"><i>petite-caps</i></a> | <a
5134 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5135 href="#unicase"><i>unicase</i></a> | <a
5136 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5137 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5138 || <a
5139 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5140 || <a
5141 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5142 || <a href="#ordinal"><i>ordinal</i></a> || <a
5143 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5144 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5145 || <a
5146 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5147 || <a href="#ruby"><i>ruby</i></a> ]
5149 <tr>
5150 <td>Initial:
5152 <td>normal
5154 <tr>
5155 <td>Applies to:
5157 <td>all elements
5159 <tr>
5160 <td>Inherited:
5162 <td>yes
5164 <tr>
5165 <td>Percentages:
5167 <td>see individual properties
5169 <tr>
5170 <td>Media:
5172 <td>visual
5174 <tr>
5175 <td>Computed value:
5177 <td>see individual properties
5179 <tr>
5180 <td>Animatable:
5182 <td>see individual properties
5183 </table>
5185 <p>The <a href="#propdef-font-variant"
5186 title="font-variant!!property">‘<code
5187 class=property>font-variant</code>’</a> property is a shorthand for all
5188 font-variant subproperties. The value <dfn id=font-variant-normal-value
5189 title="normal!!font-variant">‘<code
5190 class=property>normal</code>’</dfn> resets all subproperties of <a
5191 href="#propdef-font-variant" title="font-variant!!property">‘<code
5192 class=property>font-variant</code>’</a> to their inital value. The <dfn
5193 id=font-variant-none-value title="none!!font-variant">‘<code
5194 class=property>none</code>’</dfn> value sets ‘<a
5195 href="#propdef-font-variant-ligatures"><code
5196 class=property>font-variant-ligatures</code></a>’ to ‘<code
5197 class=property>none</code>’ and resets all other font feature properties
5198 to their initial value. Like other shorthands, using <a
5199 href="#propdef-font-variant" title="font-variant!!property">‘<code
5200 class=property>font-variant</code>’</a> resets unspecified <a
5201 href="#propdef-font-variant" title="font-variant!!property">‘<code
5202 class=property>font-variant</code>’</a> subproperties to their initial
5203 values. It does not reset the values of either ‘<a
5204 href="#propdef-font-language-override"><code
5205 class=property>font-language-override</code></a>’ or <a
5206 href="#propdef-font-feature-settings"
5207 title="font-feature-settings!!property">‘<code
5208 class=property>font-feature-settings</code>’</a>.
5210 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5211 font feature settings control: the <a
5212 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5214 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5215 <tbody>
5216 <tr>
5217 <td>Name:
5219 <td><dfn id=propdef-font-feature-settings
5220 title="font-feature-settings!!property">font-feature-settings</dfn>
5222 <tr>
5223 <td>Value:
5225 <td><a href="#font-feature-settings-normal-value"
5226 title="normal!!font-feature-settings">normal</a> | <a
5227 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5229 <tr>
5230 <td>Initial:
5232 <td>normal
5234 <tr>
5235 <td>Applies to:
5237 <td>all elements
5239 <tr>
5240 <td>Inherited:
5242 <td>yes
5244 <tr>
5245 <td>Percentages:
5247 <td>N/A
5249 <tr>
5250 <td>Media:
5252 <td>visual
5254 <tr>
5255 <td>Computed value:
5257 <td>as specified
5259 <tr>
5260 <td>Animatable:
5262 <td>no
5263 </table>
5265 <p>This property provides low-level control over OpenType font features. It
5266 is intended as a way of providing access to font features that are not
5267 widely used but are needed for a particular use case.
5269 <p>Authors should generally use <a href="#propdef-font-variant"
5270 title="font-variant!!property">‘<code
5271 class=property>font-variant</code>’</a> and its related subproperties
5272 whenever possible and only use this property for special cases where its
5273 use is the only way of accessing a particular infrequently used font
5274 feature.
5276 <pre>/* enable small caps and use second swash alternate */
5277 font-feature-settings: "smcp", "swsh" 2;</pre>
5279 <p>A value of <dfn id=font-feature-settings-normal-value
5280 title="normal!!font-feature-settings">‘<code
5281 class=property>normal</code>’</dfn> means that no change in glyph
5282 selection or positioning occurs due to this property.
5284 <p>Feature tag values have the following syntax:
5286 <pre
5287 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5289 <p>The <string> is a case-sensitive OpenType feature tag. As
5290 specified in the OpenType specification, feature tags contain four ASCII
5291 characters. Tag strings longer or shorter than four characters, or
5292 containing characters outside the U+20–7E codepoint range are invalid.
5293 Feature tags need only match a feature tag defined in the font, so they
5294 are not limited to explicitly registered OpenType features. Fonts defining
5295 custom feature tags should follow the <a
5296 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5297 rules</a> defined in the OpenType specification <a
5298 href="#OPENTYPE-FEATURES"
5299 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5301 <p>Feature tags not present in the font are ignored; a user agent must not
5302 attempt to synthesize fallback behavior based on these feature tags. The
5303 one exception is that user agents may synthetically support the <span
5304 class=tag>kern</span> feature with fonts that contain kerning data in the
5305 form of a ‘<code class=property>kern</code>’ table but lack <span
5306 class=tag>kern</span> feature support in the ‘<code
5307 class=property>GPOS</code>’ table.
5309 <p class=note>In general, authors should use the ‘<a
5310 href="#propdef-font-kerning"><code
5311 class=property>font-kerning</code></a>’ property to explicitly enable or
5312 disable kerning since this property always affects fonts with either type
5313 of kerning data.
5315 <p>If present, a value indicates an index used for glyph selection. An
5316 <integer> value must be 0 or greater. A value of 0 indicates that
5317 the feature is disabled. For boolean features, a value of 1 enables the
5318 feature. For non-boolean features, a value of 1 or greater enables the
5319 feature and indicates the feature selection index. A value of ‘<code
5320 class=property>on</code>’ is synonymous with 1 and ‘<code
5321 class=property>off</code>’ is synonymous with 0. If the value is
5322 omitted, a value of 1 is assumed.
5324 <pre>
5325 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5326 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5327 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5328 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5329 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5330 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5331 font-feature-settings: "silly" off; /* invalid, tag too long */
5332 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5333 font-feature-settings: dlig; /* invalid, tag must be a string */
5334 </pre>
5336 <p>When values greater than the range supported by the font are specified,
5337 the behavior is explicitly undefined. For boolean features, in general
5338 these will enable the feature. For non-boolean features, out of range
5339 values will in general be equivalent to a 0 value. However, in both cases
5340 the exact behavior will depend upon the way the font is designed
5341 (specifically, which type of lookup is used to define the feature).
5343 <p>Although specifically defined for OpenType feature tags, feature tags
5344 for other modern font formats that support font features may be added in
5345 the future. Where possible, features defined for other font formats should
5346 attempt to follow the pattern of registered OpenType tags.
5348 <div class=example>
5349 <p>The Japanese text below will be rendered with half-width kana
5350 characters:</p>
5352 <pre lang=ja>
5353 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5355 <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>
5356 </pre>
5357 </div>
5359 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5360 language override: the <a
5361 href="#propdef-font-language-override">font-language-override</a> property</h3>
5363 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5364 <tbody>
5365 <tr>
5366 <td>Name:
5368 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5370 <tr>
5371 <td>Value:
5373 <td><a href="#font-language-override-normal-value"
5374 title="normal!!font-language-override">normal</a> | <a
5375 href="#font-language-override-string-value"><var><string></var></a>
5377 <tr>
5378 <td>Initial:
5380 <td><a href="#font-language-override-normal-value"
5381 title="normal!!font-language-override">normal</a>
5383 <tr>
5384 <td>Applies to:
5386 <td>all elements
5388 <tr>
5389 <td>Inherited:
5391 <td>yes
5393 <tr>
5394 <td>Percentages:
5396 <td>N/A
5398 <tr>
5399 <td>Media:
5401 <td>visual
5403 <tr>
5404 <td>Computed value:
5406 <td>as specified
5408 <tr>
5409 <td>Animatable:
5411 <td>no
5412 </table>
5414 <p>Normally, authors can control the use of language-specific glyph
5415 substitutions and positioning by setting the content language of an
5416 element, as <a href="#language-specific-support">described above</a>:
5418 <pre><!-- Display text using S'gaw Karen specific features -->
5419 <p lang="ksw">...</p></pre>
5421 <p>In some cases, authors may need to specify a language system that
5422 differs from the content language, for example due to the need to mimic
5423 another language's typographic traditions. The ‘<a
5424 href="#propdef-font-language-override"><code
5425 class=property>font-language-override</code></a>’ property allows
5426 authors to explicitly specify the language system of the font, overriding
5427 the language system implied by the content language.
5429 <p>Values have the following meanings:
5431 <dl>
5432 <dt><dfn id=font-language-override-normal-value
5433 title="normal!!font-language-override">normal</dfn>
5435 <dd>specifies that when rendering with OpenType fonts, the content
5436 language of the element is used to infer the OpenType language system
5438 <dt><dfn
5439 id=font-language-override-string-value><var><string></var></dfn>
5441 <dd>single three-letter case-sensitive OpenType <a
5442 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5443 system tag</a>, specifies the OpenType language system to be used instead
5444 of the language system implied by the language of the element
5445 </dl>
5446 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5447 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5449 <p>Use of invalid OpenType language system tags must not generate a parse
5450 error but must be ignored when doing glyph selection and placement.
5452 <div class=example>
5453 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5454 Declaration of Human Rights</a> has been translated into a wide variety
5455 of languages. In Turkish, Article 9 of this document might be marked up
5456 as below:</p>
5458 <pre lang=tr><body lang="tr">
5460 <h4>Madde 9</h4>
5461 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5462 </pre>
5464 <p>Here the user agent uses the value of the ‘<code
5465 class=property>lang</code>’ attribute when rendering text and
5466 appropriately renders this text without ‘<code
5467 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5468 href="#propdef-font-language-override"><code
5469 class=property>font-language-override</code></a>’ property.</p>
5471 <p>However, a given font may lack support for a specific language. In this
5472 situation authors may need to use the typographic conventions of a
5473 related language that are supported by that font:</p>
5475 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5477 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5479 <h4>Члeн 9</h4>
5480 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5482 </pre>
5484 <p>The Macedonian text here will be rendered using Serbian typographic
5485 conventions, with the assumption that the font specified supports
5486 Serbian.</p>
5487 </div>
5489 <p><a id=rendering-considerations></a>
5491 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5492 Resolution</h2>
5494 <p>As described in the previous section, font features can be enabled in a
5495 variety of ways, either via the use of <a href="#propdef-font-variant"
5496 title="font-variant!!property">‘<code
5497 class=property>font-variant</code>’</a> or <a
5498 href="#propdef-font-feature-settings"
5499 title="font-feature-settings!!property">‘<code
5500 class=property>font-feature-settings</code>’</a> in a style rule or
5501 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5502 The resolution order for the union of these settings is defined below.
5503 Features defined via CSS properties are applied on top of layout engine
5504 default features.
5506 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5508 <p>For OpenType fonts, user agents must enable the default features defined
5509 in the OpenType documentation for a given script and writing mode.
5510 Required ligatures, common ligatures and contextual forms must be enabled
5511 by default (OpenType features: <span class=tag>rlig, liga, clig,
5512 calt</span>), along with localized forms (OpenType feature: <span
5513 class=tag>locl</span>), and features required for proper display of
5514 composed characters and marks (OpenType features: <span class=tag>ccmp,
5515 mark, mkmk</span>). These features must always be enabled, even when the
5516 value of the <a href="#propdef-font-variant"
5517 title="font-variant!!property">‘<code
5518 class=property>font-variant</code>’</a> and <a
5519 href="#propdef-font-feature-settings"
5520 title="font-feature-settings!!property">‘<code
5521 class=property>font-feature-settings</code>’</a> properties is <span
5522 title="normal value">‘<code class=property>normal</code>’</span>.
5523 Individual features are only disabled when explicitly overridden by the
5524 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5525 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5526 href="#no-common-ligatures"><code
5527 class=property>no-common-ligatures</code></a>’. For handling complex
5528 scripts such as <a
5529 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5530 <a
5531 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5532 or <a
5533 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5534 additional features are required. For upright text within vertical text
5535 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5536 must be enabled.
5538 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5540 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5541 feature property settings are resolved in the order below, in ascending
5542 order of precedence. This ordering is used to construct a combined list of
5543 font features that affect a given text run.
5545 <ol>
5546 <li>Font features enabled by default, including features required for a
5547 given script.
5549 <li>If the font is defined via an <a
5550 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5551 features implied by the font-variant descriptor in the <a
5552 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5554 <li>If the font is defined via an <a
5555 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5556 features implied by the font-feature-settings descriptor in the <a
5557 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5559 <li>Font features implied by the value of the <a
5560 href="#propdef-font-variant" title="font-variant!!property">‘<code
5561 class=property>font-variant</code>’</a> property, the related <a
5562 href="#propdef-font-variant" title="font-variant!!property">‘<code
5563 class=property>font-variant</code>’</a> subproperties and any other CSS
5564 property that uses OpenType features (e.g. the ‘<a
5565 href="#propdef-font-kerning"><code
5566 class=property>font-kerning</code></a>’ property).</li>
5567 <!-- other CSS props override 'font-variant' but not 'font-feature-settings' -->
5568 <!-- http://lists.w3.org/Archives/Public/www-style/2013Aug/0110.html -->
5570 <li>Feature settings determined by properties other than <a
5571 href="#propdef-font-variant" title="font-variant!!property">‘<code
5572 class=property>font-variant</code>’</a> or <a
5573 href="#propdef-font-feature-settings"
5574 title="font-feature-settings!!property">‘<code
5575 class=property>font-feature-settings</code>’</a>. For example, setting
5576 a non-default value for the ‘<code
5577 class=property>letter-spacing</code>’ property disables common
5578 ligatures.
5580 <li>Font features implied by the value of <a
5581 href="#propdef-font-feature-settings"
5582 title="font-feature-settings!!property">‘<code
5583 class=property>font-feature-settings</code>’</a> property.
5584 </ol>
5586 <p>This ordering allows authors to set up a general set of defaults for
5587 fonts within their <a
5588 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5589 them with property settings for specific elements. General property
5590 settings override the settings in <a
5591 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5592 font feature settings override <a href="#propdef-font-variant"
5593 title="font-variant!!property">‘<code
5594 class=property>font-variant</code>’</a> property settings.
5596 <p>For situations where the combined list of font feature settings contains
5597 more than one value for the same feature, the last value is used. When a
5598 font lacks support for a given underlying font feature, text is simply
5599 rendered as if that font feature was not enabled; font fallback does not
5600 occur and no attempt is made to synthesize the feature except where
5601 explicitly defined for specific properties.
5603 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5604 precedence examples</h3>
5606 <div class=example>
5607 <p>With the styles below, numbers are rendered proportionally when used
5608 within a paragraph but are shown in tabular form within tables of prices:</p>
5610 <pre>body {
5611 font-variant-numeric: proportional-nums;
5612 }
5614 table.prices td {
5615 font-variant-numeric: tabular-nums;
5616 }
5617 </pre>
5618 </div>
5620 <div class=example>
5621 <p>When the <a href="#descdef-font-variant"
5622 title="font-variant!!descriptor">font-variant</a> descriptor is used
5623 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5624 it only applies to the font defined by that rule.</p>
5626 <pre>@font-face {
5627 font-family: MainText;
5628 src: url(http://example.com/font.woff);
5629 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5630 }
5632 body {
5633 font-family: MainText, Helvetica;
5634 }
5636 table.prices td {
5637 font-variant-numeric: tabular-nums;
5638 }
5639 </pre>
5641 <p>In this case, old-style numerals will be used throughout but only where
5642 the font "MainText" is used. Just as in the previous example, tabular
5643 values will be used in price tables since ‘<a
5644 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5645 appears in a general style rule and its use is mutually exclusive with
5646 ‘<a href="#proportional-nums"><code
5647 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5648 will only be used where MainText is used.</p>
5649 </div>
5651 <div class=example>
5652 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5653 also be used to access font features in locally available fonts via the
5654 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5655 class=property>src</code></a>’ descriptor of the <a
5656 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5658 <pre>@font-face {
5659 font-family: BodyText;
5660 src: local("HiraMaruPro-W4");
5661 font-variant: proportional-width;
5662 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5663 }
5665 body { font-family: BodyText, serif; }
5666 </pre>
5668 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5669 text rendering occurs, Japanese kana will be proportionally spaced and
5670 Latin text will be italicised. Text rendered with the fallback serif font
5671 will use default rendering properties.</p>
5672 </div>
5674 <div class=example>
5675 <p>In the example below, discretionary ligatures are enabled only for a
5676 downloadable font but are disabled within spans of class "special":</p>
5678 <pre>@font-face {
5679 font-family: main;
5680 src: url(fonts/ffmeta.woff) format("woff");
5681 font-variant: discretionary-ligatures;
5682 }
5684 body { font-family: main, Helvetica; }
5685 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5686 </pre>
5688 <p>Suppose one adds a rule using ‘<code
5689 class=property>font-feature-settings</code>’ to enable discretionary
5690 ligatures:</p>
5692 <pre>body { font-family: main, Helvetica; }
5693 span { font-feature-settings: "dlig"; }
5694 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5695 </pre>
5697 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5698 spans of class "special". This is because both the <a
5699 href="#propdef-font-feature-settings"
5700 title="font-feature-settings!!property">‘<code
5701 class=property>font-feature-settings</code>’</a> and ‘<a
5702 href="#propdef-font-variant-ligatures"><code
5703 class=property>font-variant-ligatures</code></a>’ properties apply to
5704 these spans. Although the ‘<code class=css>no-discretionary
5705 ligatures</code>’ setting of ‘<a
5706 href="#propdef-font-variant-ligatures"><code
5707 class=property>font-variant-ligatures</code></a>’ effectively disables
5708 the OpenType <span class=tag>dlig</span> feature, because the <a
5709 href="#propdef-font-feature-settings"
5710 title="font-feature-settings!!property">‘<code
5711 class=property>font-feature-settings</code>’</a> is resolved after
5712 that, the ‘<code class=property>dlig</code>’ value reenables
5713 discretionary ligatures.</p>
5714 </div>
5716 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5718 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5719 and <a
5720 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5721 rules can be accessed via the following extensions to the CSS Object
5722 Model.
5724 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5725 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5727 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5728 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5730 <pre class=idl>
5731 interface CSSFontFaceRule : CSSRule {
5732 attribute DOMString family;
5733 attribute DOMString src;
5734 attribute DOMString style;
5735 attribute DOMString weight;
5736 attribute DOMString stretch;
5737 attribute DOMString unicodeRange;
5738 attribute DOMString variant;
5739 attribute DOMString featureSettings;
5740 }</pre>
5742 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5743 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5744 defined a different variant of this rule. This definition supercedes that
5745 one.
5747 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5748 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5749 interface</h3>
5751 <p>The <code>CSSRule</code> interface is extended as follows:
5753 <pre class=idl>partial interface CSSRule {
5754 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5755 }</pre>
5757 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5758 interface represents a <a
5759 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5760 rule.
5762 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5763 attribute DOMString fontFamily;
5764 readonly attribute CSSFontFeatureValuesMap annotation;
5765 readonly attribute CSSFontFeatureValuesMap ornaments;
5766 readonly attribute CSSFontFeatureValuesMap stylistic;
5767 readonly attribute CSSFontFeatureValuesMap swash;
5768 readonly attribute CSSFontFeatureValuesMap characterVariant;
5769 readonly attribute CSSFontFeatureValuesMap styleset;
5770 }
5772 [MapClass(DOMString, sequence<unsigned long>)]
5773 interface CSSFontFeatureValuesMap {
5774 void set(DOMString featureValueName,
5775 (unsigned long or sequence<unsigned long>) values);
5776 }</pre>
5778 <dl class=idl-attributes>
5779 <dt><var>fontFamily</var> of type <code>DOMString</code>
5781 <dd>The list of one or more font families for which a given set of feature
5782 values is defined.
5784 <dt>value maps of type <code>CSSFontFeatureValuesMap</code>, readonly
5786 <dd>Maps of feature values associated with feature value names for a given
5787 ‘<a href="#propdef-font-variant-alternates"><code
5788 class=property>font-variant-alternates</code></a>’ value type
5789 </dl>
5791 <p>Each value map attribute of <a
5792 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5793 reflects the values defined via a corresponding <a
5794 href="#featurevalueblock"><i title="feature_value_block">feature value
5795 block</i></a>. Thus, the <var title="annotation
5796 attribute">annotation</var> attribute contains the values contained within
5797 a <code title="@annotation">@annotation</code> <a
5798 href="#featurevalueblock"><i title="feature_value_block">feature value
5799 block</i></a>, the <var title="ornaments attribute">ornaments</var>
5800 attribute contains the values contained with a <code
5801 title="@ornaments">@ornaments</code> <a href="#featurevalueblock"><i
5802 title="feature_value_block">feature value block</i></a> and so forth.
5804 <p>The <code>CSSFontFeatureValuesMap</code> interface uses the <a
5805 href="http://dev.w3.org/2006/webapi/WebIDL/#es-map-members">default map
5806 class methods</a> but the <code>set</code> method has different behavior.
5807 It takes a sequence of unsigned integers and associates it with a given
5808 <code>featureValueName</code>. The method behaves the same as the default
5809 map class method except that a single unsigned long value is treated as a
5810 sequence of a single value. The method throws an exception if an invalid
5811 number of values is passed in. If the associated <a
5812 href="#featurevalueblock"><i title="feature_value_block">feature value
5813 block</i></a> only allows a limited number of values, the <code>set</code>
5814 method throws an <code>InvalidAccessError</code> exception when the input
5815 sequence to <code>set</code> contains more than the limited number of
5816 values. See the description of <a
5817 href="#multi-valued-feature-value-definitions">multi-valued feature value
5818 definitions</a> for details on the maximum number of values allowed for a
5819 given type of <a href="#featurevalueblock"><i
5820 title="feature_value_block">feature value block</i></a>. The
5821 <code>get</code> method always returns a sequence of values, even if the
5822 sequence only contains a single value.
5824 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5825 properties to CSS properties</h2>
5827 <p><em>This appendix is included as background for some of the problems and
5828 situations that are described in other sections. It should be viewed as
5829 informative only.</em>
5831 <p>Font properties in CSS are designed to be independent of the underlying
5832 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5833 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5834 are facets of the TrueType and OpenType formats that often cause confusion
5835 for authors and present challenges to implementers on different platforms.
5837 <p>Originally developed at Apple, TrueType was designed as an outline font
5838 format for both screen and print. Microsoft joined Apple in developing the
5839 TrueType format and both platforms have supported TrueType fonts since
5840 then. Font data in the TrueType format consists of a set of tables
5841 distinguished with common four-letter tag names, each containing a
5842 specific type of data. For example, naming information, including
5843 copyright and license information, is stored in the ‘<code
5844 class=property>name</code>’ table. The <a
5845 href="#character-map"><em>character map</em></a> (‘<code
5846 class=property>cmap</code>’) table contains a mapping of character
5847 encodings to glyphs. Apple later added additional tables for supporting
5848 enhanced typographic functionality; these are now called Apple Advanced
5849 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5850 tables for advanced typography and called their format OpenType <a
5851 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5853 <p>In many cases the font data used under Microsoft Windows or Linux is
5854 slightly different from the data used under Apple's Mac OS X because the
5855 TrueType format allowed for explicit variation across platforms. This
5856 includes font metrics, names and <a href="#character-map"><em>character
5857 map</em></a> data.
5859 <p>Specifically, font family name data is handled differently across
5860 platforms. For TrueType and OpenType fonts these names are contained in
5861 the ‘<code class=property>name</code>’ table, in name records with
5862 name ID 1. Mulitple names can be stored for different locales, but
5863 Microsoft recommends fonts always include at least a US English version of
5864 the name. On Windows, Microsoft made the decision for backwards
5865 compatibility to limit this family name to a maximum of four faces; for
5866 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5867 ID 21) can be used. Other platforms such as OSX don't have this
5868 limitation, so the family name is used to define all possible groupings.
5870 <p>Other name table data provides names used to uniquely identify a
5871 specific face within a family. The full font name (name ID 4) and the
5872 Postscript name (name ID 6) describe a single face uniquely. For example,
5873 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5874 and a Postscript name of "GillSans-Bold". There can be multiple localized
5875 versions of the fullname for a given face, but the Postscript name is
5876 always a unique name made from a limited set of ASCII characters.
5878 <p>On various platforms, different names are used to search for a font. For
5879 example, with the Windows GDI CreateIndirectFont API, either a family or
5880 fullname can be used to lookup a face, while on Mac OS X the
5881 CTFontCreateWithName API call is used to lookup a given face using the
5882 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5883 to be searched using any of these names. In situations where platform
5884 API's automatically substitute other font choices, it may be necessary to
5885 verify a returned font matches a given name.
5887 <p>The weight of a given face can be determined via the usWeightClass field
5888 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5889 the width can be determined via the usWidthClass of the OS/2 table or
5890 inferred from the style name. For historical reasons related to synthetic
5891 bolding at weights 200 or lower with the Windows GDI API, font designers
5892 have sometimes skewed values in the OS/2 table to avoid these weights.
5894 <p>Rendering complex scripts that use contextual shaping such as Thai,
5895 Arabic and Devanagari requires features present only in OpenType or AAT
5896 fonts. Currently, complex script rendering is supported on Windows and
5897 Linux using OpenType font features while both OpenType and AAT font
5898 features are used under Mac OS X.
5900 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5902 <h3 class=no-num id=recent-changes> Changes from the <a
5903 href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">July 2013 CSS3
5904 Fonts Last Call Working Draft</a></h3>
5906 <p>Major changes include:
5908 <ul>
5909 <li>reorder feature precedence such that features implied by other CSS
5910 properties override ‘<code class=property>font-variant</code>’
5911 settings
5913 <li>switched examples to use .woff files
5915 <li>revised wording of font fetching algorithm
5917 <li>clarify meaning of <a href="#font-size-adjust-auto-value"
5918 title="auto!!font-size-adjust">‘<code class=property>auto</code>’</a>
5919 value for ‘<a href="#propdef-font-size-adjust"><code
5920 class=property>font-size-adjust</code></a>’
5922 <li>allow user agents to synthesize OpenType <span class=tag>kern</span>
5923 feature
5925 <li>minor editorial cleanups
5926 </ul>
5928 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5930 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5931 their help and feedback. John Hudson was kind enough to take the time to
5932 explain the subtleties of OpenType language tags and provided the example
5933 of character variant usage for displaying text on Byzantine seals. Ken
5934 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5935 and Unicode variation selectors. The idea for supporting font features by
5936 using <a href="#propdef-font-variant"
5937 title="font-variant!!property">‘<code
5938 class=property>font-variant</code>’</a> subproperties originated with
5939 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5940 of the initial design ideas for the <a
5941 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5942 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5943 in the discretionary ligatures example.
5945 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5946 that is <em>The Elements of Typographic Style</em>.
5948 <h2 class=no-num id=conformance> Conformance</h2>
5950 <h3 class=no-num id=conventions> Document Conventions</h3>
5952 <p>Conformance requirements are expressed with a combination of descriptive
5953 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5954 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5955 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5956 normative parts of this document are to be interpreted as described in RFC
5957 2119. However, for readability, these words do not appear in all uppercase
5958 letters in this specification.
5960 <p>All of the text of this specification is normative except sections
5961 explicitly marked as non-normative, examples, and notes. <a
5962 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5964 <p>Examples in this specification are introduced with the words “for
5965 example” or are set apart from the normative text with
5966 <code>class="example"</code>, like this:
5968 <div class=example>
5969 <p>This is an example of an informative example.
5970 </div>
5972 <p>Informative notes begin with the word “Note” and are set apart from
5973 the normative text with <code>class="note"</code>, like this:
5975 <p class=note>Note, this is an informative note.
5977 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5979 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5980 classes:
5982 <dl>
5983 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5984 sheet</dfn>
5986 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5987 style sheet</a>.
5989 <dt><dfn id=renderer>renderer</dfn>
5991 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5992 that interprets the semantics of a style sheet and renders documents that
5993 use them.
5995 <dt><dfn id=authoring-tool>authoring tool</dfn>
5997 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5998 that writes a style sheet.
5999 </dl>
6001 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
6002 declarations that use properties defined in this module have values that
6003 are valid according to the generic CSS grammar and the individual grammars
6004 of each property as given in this module.
6006 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
6007 interpreting the style sheet as defined by the appropriate specifications,
6008 it supports all the features defined by CSS Fonts Level 3 Module by
6009 parsing them correctly and rendering the document accordingly. However,
6010 the inability of a UA to correctly render a document due to limitations of
6011 the device does not make the UA non-conformant. (For example, a UA is not
6012 required to render color on a monochrome monitor.)
6014 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
6015 style sheets that are syntactically correct according to the generic CSS
6016 grammar and the individual grammars of each feature in this module, and
6017 meet all other conformance requirements of style sheets as described in
6018 this module.
6020 <h3 class=no-num id=partial> Partial Implementations</h3>
6022 <p>So that authors can exploit the forward-compatible parsing rules to
6023 assign fallback values, CSS renderers <strong>must</strong> treat as
6024 invalid (and <a
6025 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
6026 appropriate</a>) any at-rules, properties, property values, keywords, and
6027 other syntactic constructs for which they have no usable level of support.
6028 In particular, user agents <strong>must not</strong> selectively ignore
6029 unsupported component values and honor supported values in a single
6030 multi-value property declaration: if any value is considered invalid (as
6031 unsupported values must be), CSS requires that the entire declaration be
6032 ignored.
6034 <h3 class=no-num id=experimental> Experimental Implementations</h3>
6036 <p>To avoid clashes with future CSS features, the CSS2.1 specification
6037 reserves a <a
6038 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
6039 syntax</a> for proprietary and experimental extensions to CSS.
6041 <p>Prior to a specification reaching the Candidate Recommendation stage in
6042 the W3C process, all implementations of a CSS feature are considered
6043 experimental. The CSS Working Group recommends that implementations use a
6044 vendor-prefixed syntax for such features, including those in W3C Working
6045 Drafts. This avoids incompatibilities with future changes in the draft.
6047 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
6049 <p>Once a specification reaches the Candidate Recommendation stage,
6050 non-experimental implementations are possible, and implementors should
6051 release an unprefixed implementation of any CR-level feature they can
6052 demonstrate to be correctly implemented according to spec.
6054 <p>To establish and maintain the interoperability of CSS across
6055 implementations, the CSS Working Group requests that non-experimental CSS
6056 renderers submit an implementation report (and, if necessary, the
6057 testcases used for that implementation report) to the W3C before releasing
6058 an unprefixed implementation of any CSS features. Testcases submitted to
6059 W3C are subject to review and correction by the CSS Working Group.
6061 <p>Further information on submitting testcases and implementation reports
6062 can be found from on the CSS Working Group's website at <a
6063 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
6064 Questions should be directed to the <a
6065 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
6066 mailing list.
6068 <h2 class=no-num id=references>References</h2>
6070 <h3 class=no-num id=normative-references>Normative References</h3>
6071 <!--begin-normative-->
6072 <!-- Sorted by label -->
6074 <dl class=bibliography>
6075 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6076 <!---->
6078 <dt id=CHARMOD>[CHARMOD]
6080 <dd>Martin J. Dürst; et al. <a
6081 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6082 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6083 2005. W3C Recommendation. URL: <a
6084 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6085 </dd>
6086 <!---->
6088 <dt id=CORS>[CORS]
6090 <dd>Anne van Kesteren. <a
6091 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6092 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6093 Recommendation. (Work in progress.) URL: <a
6094 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6095 </dd>
6096 <!---->
6098 <dt id=CSS21>[CSS21]
6100 <dd>Bert Bos; et al. <a
6101 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6102 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6103 2011. W3C Recommendation. URL: <a
6104 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6105 </dd>
6106 <!---->
6108 <dt id=CSS3VAL>[CSS3VAL]
6110 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6111 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
6112 Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6113 Recommendation. (Work in progress.) URL: <a
6114 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
6115 </dd>
6116 <!---->
6118 <dt id=HTML5>[HTML5]
6120 <dd>Ian Hickson. <a
6121 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
6122 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
6123 <a
6124 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
6125 </dd>
6126 <!---->
6128 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6130 <dd><a
6131 href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136"><cite>Information
6132 technology — Coding of audio-visual objects — Part 22: Open Font
6133 Format.</cite></a> International Organization for Standardization.
6134 ISO/IEC 14496-22:2009. URL: <a
6135 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>
6136 </dd>
6137 <!---->
6139 <dt id=OPENTYPE>[OPENTYPE]
6141 <dd><a
6142 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6143 specification.</cite></a> Microsoft. URL: <a
6144 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6145 </dd>
6146 <!---->
6148 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6150 <dd><a
6151 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6152 feature registry.</cite></a> Microsoft. URL: <a
6153 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6154 </dd>
6155 <!---->
6157 <dt id=RFC2119>[RFC2119]
6159 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6160 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6161 RFC 2119. URL: <a
6162 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6163 </dd>
6164 <!---->
6166 <dt id=UAX15>[UAX15]
6168 <dd>Mark Davis; Ken Whistler. <a
6169 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6170 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6171 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6172 </dd>
6173 <!---->
6175 <dt id=UAX29>[UAX29]
6177 <dd>Mark Davis. <a
6178 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6179 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6180 URL: <a
6181 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6182 </dd>
6183 <!---->
6185 <dt id=UNICODE6>[UNICODE6]
6187 <dd>The Unicode Consortium. <a
6188 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6189 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6190 Version 6.2.0 URL: <a
6191 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6192 </dd>
6193 <!---->
6194 </dl>
6195 <!--end-normative-->
6196 <!--{{!CSS21}}-->
6197 <!--{{!CSS3VAL}}-->
6198 <!--{{!OPENTYPE}}-->
6199 <!--{{!OPENTYPE-FEATURES}}-->
6200 <!--{{!OPEN-FONT-FORMAT}}-->
6201 <!--{{!UNICODE6}}-->
6202 <!--{{!UAX15}}-->
6203 <!--{{!UAX29}}-->
6204 <!--{{!CORS}}-->
6205 <!--{{!HTML5}}-->
6206 <!--{{!CHARMOD}}-->
6208 <h3 class=no-num id=other-references>Other References</h3>
6209 <!--begin-informative-->
6210 <!-- Sorted by label -->
6212 <dl class=bibliography>
6213 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6214 <!---->
6216 <dt id=AAT-FEATURES>[AAT-FEATURES]
6218 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6219 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6220 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6221 </dd>
6222 <!---->
6224 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6226 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6227 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6228 <!---->
6230 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6232 <dd>François Yergeau; et al. <a
6233 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6234 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6235 W3C Working Draft. (Work in progress.) URL: <a
6236 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6237 </dd>
6238 <!---->
6240 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6242 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6243 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6244 <!---->
6246 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6248 <dd>L. David Baron. <a
6249 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6250 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6251 Recommendation. (Work in progress.) URL: <a
6252 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6253 </dd>
6254 <!---->
6256 <dt id=CSS3TEXT>[CSS3TEXT]
6258 <dd>Elika J. Etemad; Koji Ishii. <a
6259 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6260 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6261 progress.) URL: <a
6262 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6263 </dd>
6264 <!---->
6266 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6268 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6269 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6270 ISBN 0-201-17633-5.</dd>
6271 <!---->
6273 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6275 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6276 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6277 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6278 2000. W3C Recommendation. URL: <a
6279 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>
6280 </dd>
6281 <!---->
6283 <dt id=ELEMTYPO>[ELEMTYPO]
6285 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6286 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6287 <!---->
6289 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6291 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6292 ISBN 1-932026-01-0.</dd>
6293 <!---->
6295 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6297 <dd><a
6298 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6299 User Guide.</cite></a> FontShop International. URL: <a
6300 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6301 </dd>
6302 <!---->
6304 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6306 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6307 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6308 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6309 <!---->
6311 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6313 <dd>John Hudson. <a
6314 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6315 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6316 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6317 </dd>
6318 <!---->
6319 </dl>
6320 <!--end-informative-->
6321 <!--{{ARABIC-TYPO}}-->
6322 <!--{{CJKV-INFO-PROCESSING}}-->
6323 <!--{{DIGITAL-TYPOGRAPHY}}-->
6324 <!--{{DOM-LEVEL-2-STYLE}}-->
6325 <!--{{ELEMTYPO}}-->
6326 <!--{{LANGCULTTYPE}}-->
6327 <!--{{OPENTYPE-FONT-GUIDE}}-->
6328 <!--{{RASTER-TRAGEDY}}-->
6329 <!--{{WINDOWS-GLYPH-PROC}}-->
6330 <!--{{CHARMOD-NORM}}-->
6331 <!--{{AAT-FEATURES}}-->
6332 <!--{{CSS3-CONDITIONAL}}-->
6333 <!--{{CSS3TEXT}}-->
6335 <h2 class=no-num id=index>Index</h2>
6336 <!--begin-index-->
6338 <ul class=indexlist>
6339 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6340 title="100...900 weight values"><strong>3.2</strong></a>
6342 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6343 title="<absolute-size>"><strong>3.5</strong></a>
6345 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6346 title="<common-lig-values>"><strong>6.4</strong></a>
6348 <li><var><contextual-alt-values></var>, <a
6349 href="#contextual-alt-values"
6350 title="<contextual-alt-values>"><strong>6.4</strong></a>
6352 <li><var><discretionary-lig-values></var>, <a
6353 href="#discretionary-lig-values"
6354 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6356 <li><var><east-asian-variant-values></var>, <a
6357 href="#east-asian-variant-values"
6358 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6360 <li><var><east-asian-width-values></var>, <a
6361 href="#east-asian-width-values"
6362 title="<east-asian-width-values>"><strong>6.10</strong></a>
6364 <li><var><family-name></var>, <a href="#family-name-value"
6365 title="<family-name>"><strong>3.1</strong></a>
6367 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6368 title="<feature-tag-value>"><strong>6.12</strong></a>
6370 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6371 title="<font-face-name>"><strong>4.3</strong></a>
6373 <li><var><font-variant-css21></var>, <a
6374 href="#font-variant-css21-values"
6375 title="<font-variant-css21>"><strong>3.7</strong></a>
6377 <li><var><generic-family></var>, <a href="#generic-family-value"
6378 title="<generic-family>"><strong>3.1</strong></a>
6380 <li><var><historical-lig-values></var>, <a
6381 href="#historical-lig-values"
6382 title="<historical-lig-values>"><strong>6.4</strong></a>
6384 <li><var><length></var>, <a href="#length-size-value"
6385 title="<length>"><strong>3.5</strong></a>
6387 <li><var><number></var>, <a href="#aspect-ratio-value"
6388 title="<number>"><strong>3.6</strong></a>
6390 <li><var><numeric-figure-values></var>, <a
6391 href="#numeric-figure-values"
6392 title="<numeric-figure-values>"><strong>6.7</strong></a>
6394 <li><var><numeric-fraction-values></var>, <a
6395 href="#numeric-fraction-values"
6396 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6398 <li><var><numeric-spacing-values></var>, <a
6399 href="#numeric-spacing-values"
6400 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6402 <li><var><percentage></var>, <a href="#percentage-size-value"
6403 title="<percentage>"><strong>3.5</strong></a>
6405 <li><var><relative-size></var>, <a href="#relative-size-value"
6406 title="<relative-size>"><strong>3.5</strong></a>
6408 <li><var><string></var>, <a
6409 href="#font-language-override-string-value"
6410 title="<string>"><strong>6.13</strong></a>
6412 <li><var><urange></var>, <a href="#urange-value"
6413 title="<urange>"><strong>4.5</strong></a>
6415 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6416 title="@font-face"><strong>4.1</strong></a>
6418 <li><code>@font-feature-values</code>, <a
6419 href="#at-font-feature-values-rule"
6420 title="@font-feature-values"><strong>6.9</strong></a>
6422 <li>all-petite-caps, <a href="#all-petite-caps"
6423 title=all-petite-caps><strong>6.6</strong></a>
6425 <li>all-small-caps, <a href="#all-small-caps"
6426 title=all-small-caps><strong>6.6</strong></a>
6428 <li>annotation, <a href="#annotation"
6429 title=annotation><strong>6.8</strong></a>
6431 <li>aspect value, <a href="#aspect-value0" title="aspect
6432 value"><strong>3.6</strong></a>
6434 <li>authoring tool, <a href="#authoring-tool" title="authoring
6435 tool"><strong>#</strong></a>
6437 <li>auto
6438 <ul>
6439 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6440 font-kerning"><strong>6.3</strong></a>
6442 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6443 title="auto, font-size-adjust"><strong>3.6</strong></a>
6444 </ul>
6446 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6448 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6450 <li>character map, <a href="#character-map" title="character
6451 map"><strong>5.2</strong></a>
6453 <li>character-variant, <a href="#character-variant"
6454 title=character-variant><strong>6.8</strong></a>
6456 <li>common-ligatures, <a href="#common-ligatures"
6457 title=common-ligatures><strong>6.4</strong></a>
6459 <li>composite face, <a href="#composite-face" title="composite
6460 face"><strong>5.2</strong></a>
6462 <li>condensed, <a href="#condensed"
6463 title=condensed><strong>3.3</strong></a>
6465 <li>contextual, <a href="#contextual"
6466 title=contextual><strong>6.4</strong></a>
6468 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6469 title=CSSFontFaceRule><strong>8.1</strong></a>
6471 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6472 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6474 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6475 of"><strong>#</strong></a>
6477 <li>default face, <a href="#default-face" title="default
6478 face"><strong>5.2</strong></a>
6480 <li>descriptor_declaration, <a href="#descriptordeclaration"
6481 title="descriptor_declaration"><strong>4.1</strong></a>
6483 <li>diagonal-fractions, <a href="#diagonal-fractions"
6484 title=diagonal-fractions><strong>6.7</strong></a>
6486 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6487 title=discretionary-ligatures><strong>6.4</strong></a>
6489 <li>effective character map, <a href="#effective-character-map"
6490 title="effective character map"><strong>4.5</strong></a>
6492 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6494 <li>extra-condensed, <a href="#extra-condensed"
6495 title=extra-condensed><strong>3.3</strong></a>
6497 <li>extra-expanded, <a href="#extra-expanded"
6498 title=extra-expanded><strong>3.3</strong></a>
6500 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6501 of"><strong>#</strong></a>
6503 <li>feature_type, <a href="#featuretype"
6504 title="feature_type"><strong>6.9.1</strong></a>
6506 <li>feature_value_block, <a href="#featurevalueblock"
6507 title="feature_value_block"><strong>6.9.1</strong></a>
6509 <li>feature_value_definition, <a href="#featurevaluedefinition"
6510 title="feature_value_definition"><strong>6.9.1</strong></a>
6512 <li>first available font, <a href="#first-available-font" title="first
6513 available font"><strong>5.2</strong></a>
6515 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6517 <li>font specific, <a href="#font-specific" title="font
6518 specific"><strong>6.8</strong></a>
6520 <li>font-family
6521 <ul>
6522 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6523 descriptor"><strong>4.2</strong></a>
6525 <li>property, <a href="#propdef-font-family" title="font-family,
6526 property"><strong>3.1</strong></a>
6527 </ul>
6529 <li>font-feature-settings
6530 <ul>
6531 <li>descriptor, <a href="#descdef-font-feature-settings"
6532 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6534 <li>property, <a href="#propdef-font-feature-settings"
6535 title="font-feature-settings, property"><strong>6.12</strong></a>
6536 </ul>
6538 <li>font-kerning, <a href="#propdef-font-kerning"
6539 title=font-kerning><strong>6.3</strong></a>
6541 <li>font-language-override, <a href="#propdef-font-language-override"
6542 title=font-language-override><strong>6.13</strong></a>
6544 <li>font-size, <a href="#propdef-font-size"
6545 title=font-size><strong>3.5</strong></a>
6547 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6548 title=font-size-adjust><strong>3.6</strong></a>
6550 <li>font-stretch
6551 <ul>
6552 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6553 descriptor"><strong>4.4</strong></a>
6555 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6556 property"><strong>3.3</strong></a>
6557 </ul>
6559 <li>font-style
6560 <ul>
6561 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6562 descriptor"><strong>4.4</strong></a>
6564 <li>property, <a href="#propdef-font-style" title="font-style,
6565 property"><strong>3.4</strong></a>
6566 </ul>
6568 <li>font-synthesis, <a href="#propdef-font-synthesis"
6569 title=font-synthesis><strong>3.8</strong></a>
6571 <li>font-variant
6572 <ul>
6573 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6574 descriptor"><strong>4.7</strong></a>
6576 <li>property, <a href="#propdef-font-variant" title="font-variant,
6577 property"><strong>6.11</strong></a>
6578 </ul>
6580 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6581 title=font-variant-alternates><strong>6.8</strong></a>
6583 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6584 title=font-variant-caps><strong>6.6</strong></a>
6586 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6587 title=font-variant-east-asian><strong>6.10</strong></a>
6589 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6590 title=font-variant-ligatures><strong>6.4</strong></a>
6592 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6593 title=font-variant-numeric><strong>6.7</strong></a>
6595 <li>font-variant-position, <a href="#propdef-font-variant-position"
6596 title=font-variant-position><strong>6.5</strong></a>
6598 <li>font-weight
6599 <ul>
6600 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6601 descriptor"><strong>4.4</strong></a>
6603 <li>property, <a href="#propdef-font-weight" title="font-weight,
6604 property"><strong>3.2</strong></a>
6605 </ul>
6607 <li>font_face_rule, <a href="#fontfacerule"
6608 title="font_face_rule"><strong>4.1</strong></a>
6610 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6611 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6613 <li>font_family_name, <a href="#fontfamilyname"
6614 title="font_family_name"><strong>6.9.1</strong></a>
6616 <li>font_family_name_list, <a href="#fontfamilynamelist"
6617 title="font_family_name_list"><strong>6.9.1</strong></a>
6619 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6620 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6622 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6623 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6625 <li>full-width, <a href="#full-width"
6626 title=full-width><strong>6.10</strong></a>
6628 <li>historical-forms, <a href="#historical-forms"
6629 title=historical-forms><strong>6.8</strong></a>
6631 <li>historical-ligatures, <a href="#historical-ligatures"
6632 title=historical-ligatures><strong>6.4</strong></a>
6634 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6636 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6638 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6640 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6642 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6644 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6646 <li>lining-nums, <a href="#lining-nums"
6647 title=lining-nums><strong>6.7</strong></a>
6649 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6650 definition of"><strong>#</strong></a>
6652 <li>no-common-ligatures, <a href="#no-common-ligatures"
6653 title=no-common-ligatures><strong>6.4</strong></a>
6655 <li>no-contextual, <a href="#no-contextual"
6656 title=no-contextual><strong>6.4</strong></a>
6658 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6659 title=no-discretionary-ligatures><strong>6.4</strong></a>
6661 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6662 title=no-historical-ligatures><strong>6.4</strong></a>
6664 <li>none
6665 <ul>
6666 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6667 font-kerning"><strong>6.3</strong></a>
6669 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6670 title="none, font-size-adjust"><strong>3.6</strong></a>
6672 <li>font-variant, <a href="#font-variant-none-value" title="none,
6673 font-variant"><strong>6.11</strong></a>
6675 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6676 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6677 </ul>
6679 <li>normal
6680 <ul>
6681 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6682 title="normal, font-feature-settings"><strong>6.12</strong></a>
6684 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6685 font-kerning"><strong>6.3</strong></a>
6687 <li>font-language-override, <a
6688 href="#font-language-override-normal-value" title="normal,
6689 font-language-override"><strong>6.13</strong></a>
6691 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6692 font-stretch"><strong>3.3</strong></a>
6694 <li>font-style, <a href="#font-style-normal-value" title="normal,
6695 font-style"><strong>3.4</strong></a>
6697 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6698 font-variant"><strong>6.11</strong></a>
6700 <li>font-variant-alternates, <a
6701 href="#font-variant-alternates-normal-value" title="normal,
6702 font-variant-alternates"><strong>6.8</strong></a>
6704 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6705 title="normal, font-variant-caps"><strong>6.6</strong></a>
6707 <li>font-variant-east-asian, <a
6708 href="#font-variant-east-asian-normal-value" title="normal,
6709 font-variant-east-asian"><strong>6.10</strong></a>
6711 <li>font-variant-ligatures, <a
6712 href="#font-variant-ligatures-normal-value" title="normal,
6713 font-variant-ligatures"><strong>6.4</strong></a>
6715 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6716 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6718 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6719 title="normal, font-variant-position"><strong>6.5</strong></a>
6721 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6722 font-weight"><strong>3.2</strong></a>
6723 </ul>
6725 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6727 <li>oldstyle-nums, <a href="#oldstyle-nums"
6728 title=oldstyle-nums><strong>6.7</strong></a>
6730 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6732 <li>ornaments, <a href="#ornaments"
6733 title=ornaments><strong>6.8</strong></a>
6735 <li>petite-caps, <a href="#petite-caps"
6736 title=petite-caps><strong>6.6</strong></a>
6738 <li>proportional-nums, <a href="#proportional-nums"
6739 title=proportional-nums><strong>6.7</strong></a>
6741 <li>proportional-width, <a href="#proportional-width"
6742 title=proportional-width><strong>6.10</strong></a>
6744 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6746 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6748 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6749 definition of"><strong>#</strong></a>
6751 <li>semi-condensed, <a href="#semi-condensed-"
6752 title=semi-condensed><strong>3.3</strong></a>
6754 <li>semi-expanded, <a href="#semi-expanded"
6755 title=semi-expanded><strong>3.3</strong></a>
6757 <li>serif, definition of, <a href="#serif0" title="serif, definition
6758 of"><strong>#</strong></a>
6760 <li>simplified, <a href="#simplified"
6761 title=simplified><strong>6.10</strong></a>
6763 <li>slashed-zero, <a href="#slashed-zero"
6764 title=slashed-zero><strong>6.7</strong></a>
6766 <li>small-caps, <a href="#small-caps"
6767 title=small-caps><strong>6.6</strong></a>
6769 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6771 <li>stacked-fractions, <a href="#stacked-fractions"
6772 title=stacked-fractions><strong>6.7</strong></a>
6774 <li>style sheet
6775 <ul>
6776 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6777 conformance class"><strong>#</strong></a>
6778 </ul>
6780 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6782 <li>stylistic, <a href="#stylistic"
6783 title=stylistic><strong>6.8</strong></a>
6785 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6787 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6789 <li>support, <a href="#support" title=support><strong>5.2</strong></a>
6791 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6793 <li>system font fallback, <a href="#system-font-fallback" title="system
6794 font fallback"><strong>5.2</strong></a>
6796 <li>tabular-nums, <a href="#tabular-nums"
6797 title=tabular-nums><strong>6.7</strong></a>
6799 <li>titling-caps, <a href="#titling-caps"
6800 title=titling-caps><strong>6.6</strong></a>
6802 <li>traditional, <a href="#traditional"
6803 title=traditional><strong>6.10</strong></a>
6805 <li>ultra-condensed, <a href="#ultra-condensed"
6806 title=ultra-condensed><strong>3.3</strong></a>
6808 <li>ultra-expanded, <a href="#ultra-expanded"
6809 title=ultra-expanded><strong>3.3</strong></a>
6811 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6813 <li>unicode-range, <a href="#descdef-unicode-range"
6814 title=unicode-range><strong>4.5</strong></a>
6816 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6818 <li>width, <a href="#width" title=width><strong>2</strong></a>
6819 </ul>
6820 <!--end-index-->
6822 <h2 class=no-num id=property-index>Property index</h2>
6823 <!--begin-properties-->
6825 <table class=proptable>
6826 <thead>
6827 <tr>
6828 <th>Property
6830 <th>Values
6832 <th>Initial
6834 <th>Applies to
6836 <th>Inh.
6838 <th>Percentages
6840 <th>Media
6842 <tbody>
6843 <tr>
6844 <th><a class=property href="#propdef-font">font</a>
6846 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6847 <‘font-weight’> || <‘font-stretch’ ]?
6848 <‘font-size’> [ / <‘line-height’> ]?
6849 <‘font-family’> ] | caption | icon | menu | message-box |
6850 small-caption | status-bar
6852 <td>see individual properties
6854 <td>all elements
6856 <td>yes
6858 <td>see individual properties
6860 <td>visual
6862 <tr>
6863 <th><span class=property>font-family</span>
6865 <td>[ <family-name> | <generic-family> ] #
6867 <td>depends on user agent
6869 <td>all elements
6871 <td>yes
6873 <td>N/A
6875 <td>visual
6877 <tr>
6878 <th><span class=property>font-feature-settings</span>
6880 <td>normal | <feature-tag-value> #
6882 <td>normal
6884 <td>all elements
6886 <td>yes
6888 <td>N/A
6890 <td>visual
6892 <tr>
6893 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6895 <td>auto | normal | none
6897 <td>auto
6899 <td>all elements
6901 <td>yes
6903 <td>N/A
6905 <td>visual
6907 <tr>
6908 <th><a class=property
6909 href="#propdef-font-language-override">font-language-override</a>
6911 <td>normal | <string>
6913 <td>normal
6915 <td>all elements
6917 <td>yes
6919 <td>N/A
6921 <td>visual
6923 <tr>
6924 <th><a class=property href="#propdef-font-size">font-size</a>
6926 <td><absolute-size> | <relative-size> | <length> |
6927 <percentage>
6929 <td>medium
6931 <td>all elements
6933 <td>yes
6935 <td>refer to parent element's font size
6937 <td>visual
6939 <tr>
6940 <th><a class=property
6941 href="#propdef-font-size-adjust">font-size-adjust</a>
6943 <td>none | auto | <number>
6945 <td>none
6947 <td>all elements
6949 <td>yes
6951 <td>N/A
6953 <td>visual
6955 <tr>
6956 <th><span class=property>font-stretch</span>
6958 <td>normal | ultra-condensed | extra-condensed | condensed |
6959 semi-condensed | semi-expanded | expanded | extra-expanded |
6960 ultra-expanded
6962 <td>normal
6964 <td>all elements
6966 <td>yes
6968 <td>N/A
6970 <td>visual
6972 <tr>
6973 <th><span class=property>font-style</span>
6975 <td>normal | italic | oblique
6977 <td>normal
6979 <td>all elements
6981 <td>yes
6983 <td>N/A
6985 <td>visual
6987 <tr>
6988 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6990 <td>none | [ weight || style ]
6992 <td>weight style
6994 <td>all elements
6996 <td>yes
6998 <td>N/A
7000 <td>visual
7002 <tr>
7003 <th><span class=property>font-variant</span>
7005 <td>normal | none | [ <common-lig-values> ||
7006 <discretionary-lig-values> || <historical-lig-values> ||
7007 <contextual-alt-values> || stylistic(<feature-value-name>)
7008 || historical-forms || styleset(<feature-value-name> #) ||
7009 character-variant(<feature-value-name> #) ||
7010 swash(<feature-value-name>) ||
7011 ornaments(<feature-value-name>) ||
7012 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7013 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7014 <numeric-figure-values> || <numeric-spacing-values> ||
7015 <numeric-fraction-values> || ordinal || slashed-zero ||
7016 <east-asian-variant-values> || <east-asian-width-values> ||
7017 ruby ]
7019 <td>normal
7021 <td>all elements
7023 <td>yes
7025 <td>see individual properties
7027 <td>visual
7029 <tr>
7030 <th><a class=property
7031 href="#propdef-font-variant-alternates">font-variant-alternates</a>
7033 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
7034 || styleset(<feature-value-name> #) ||
7035 character-variant(<feature-value-name> #) ||
7036 swash(<feature-value-name>) ||
7037 ornaments(<feature-value-name>) ||
7038 annotation(<feature-value-name>) ]
7040 <td>normal
7042 <td>all elements
7044 <td>yes
7046 <td>N/A
7048 <td>visual
7050 <tr>
7051 <th><a class=property
7052 href="#propdef-font-variant-caps">font-variant-caps</a>
7054 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
7055 | unicase | titling-caps
7057 <td>normal
7059 <td>all elements
7061 <td>yes
7063 <td>N/A
7065 <td>visual
7067 <tr>
7068 <th><a class=property
7069 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
7071 <td>normal | [ <east-asian-variant-values> ||
7072 <east-asian-width-values> || ruby ]
7074 <td>normal
7076 <td>all elements
7078 <td>yes
7080 <td>N/A
7082 <td>visual
7084 <tr>
7085 <th><a class=property
7086 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
7088 <td>normal | none | [ <common-lig-values> ||
7089 <discretionary-lig-values> || <historical-lig-values> ||
7090 <contextual-alt-values> ]
7092 <td>normal
7094 <td>all elements
7096 <td>yes
7098 <td>N/A
7100 <td>visual
7102 <tr>
7103 <th><a class=property
7104 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7106 <td>normal | [ <numeric-figure-values> ||
7107 <numeric-spacing-values> || <numeric-fraction-values> ||
7108 ordinal || slashed-zero ]
7110 <td>normal
7112 <td>all elements
7114 <td>yes
7116 <td>N/A
7118 <td>visual
7120 <tr>
7121 <th><a class=property
7122 href="#propdef-font-variant-position">font-variant-position</a>
7124 <td>normal | sub | super
7126 <td>normal
7128 <td>all elements
7130 <td>yes
7132 <td>N/A
7134 <td>visual
7136 <tr>
7137 <th><span class=property>font-weight</span>
7139 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7140 | 700 | 800 | 900
7142 <td>normal
7144 <td>all elements
7146 <td>yes
7148 <td>N/A
7150 <td>visual
7151 </table>
7152 <!--end-properties-->
7153 <!--begin-descriptors-->
7155 <table class=proptable>
7156 <thead>
7157 <tr>
7158 <th>Descriptor
7160 <th>Value
7162 <th>Initial
7164 <th>Percentages
7166 <th>Media
7168 <tbody>
7169 <tr>
7170 <th><span class=property>font-family</span>
7172 <td><family-name>
7174 <td>N/A
7176 <tr>
7177 <th><span class=property>font-feature-settings</span>
7179 <td>normal | <feature-tag-value> #
7181 <td>normal
7183 <tr>
7184 <th><span class=property>font-stretch</span>
7186 <td>normal | ultra-condensed | extra-condensed | condensed |
7187 semi-condensed | semi-expanded | expanded | extra-expanded |
7188 ultra-expanded
7190 <td>normal
7192 <tr>
7193 <th><span class=property>font-style</span>
7195 <td>normal | italic | oblique
7197 <td>normal
7199 <tr>
7200 <th><span class=property>font-variant</span>
7202 <td>normal | none | [ <common-lig-values> ||
7203 <discretionary-lig-values> || <historical-lig-values> ||
7204 <contextual-alt-values> || stylistic(<feature-value-name>)
7205 || historical-forms || styleset(<feature-value-name> #) ||
7206 character-variant(<feature-value-name> #) ||
7207 swash(<feature-value-name>) ||
7208 ornaments(<feature-value-name>) ||
7209 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7210 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7211 <numeric-figure-values> || <numeric-spacing-values> ||
7212 <numeric-fraction-values> || ordinal || slashed-zero ||
7213 <east-asian-variant-values> || <east-asian-width-values> ||
7214 ruby ]
7216 <td>normal
7218 <tr>
7219 <th><span class=property>font-weight</span>
7221 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7223 <td>normal
7225 <tr>
7226 <th><a class=property href="#descdef-src">src</a>
7228 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7230 <td>N/A
7232 <tr>
7233 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7235 <td><urange> #
7237 <td>U+0-10FFFF
7238 </table>
7239 <!--end-descriptors-->
7240 <script type="text/javascript">
7241 window.onload = function () {
7242 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7243 var i, hiresElements = document.getElementsByClassName("hires");
7244 for (i = 0; i < hiresElements.length; i++) {
7245 var h = hiresElements[i];
7246 if (h.tagName != "IMG") continue;
7247 var src = h.getAttribute("src");
7248 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7249 h.src = src2x;
7250 }
7251 }
7252 </script>
7253 </html>
7254 <!-- Keep this comment at the end of the file
7255 Local variables:
7256 mode: sgml
7257 sgml-declaration:"~/SGML/HTML4.decl"
7258 sgml-default-doctype-name:"html"
7259 sgml-minimize-attributes:t
7260 sgml-nofill-elements:("pre" "style" "br")
7261 sgml-live-element-indicator:t
7262 sgml-omittag:nil
7263 sgml-shorttag:nil
7264 sgml-namecase-general:t
7265 sgml-general-insert-case:lower
7266 sgml-always-quote-attributes:t
7267 sgml-indent-step:nil
7268 sgml-indent-data:t
7269 sgml-parent-document:nil
7270 sgml-exposed-tags:nil
7271 sgml-local-catalogs:nil
7272 sgml-local-ecat-files:nil
7273 End:
7274 -->
7275 <!--
7277 to do:
7279 - wording of OpenType family name handling
7280 - handling combining sequences in the font matching algorithm
7281 - fix-up fi ligature example
7283 -->
