css-fonts/Fonts.html@f8ed09648c85
css-fonts/Fonts.html
Mon, 10 Jun 2013 17:08:11 +0900
- author
- John Daggett <jdaggett@mozilla.com>
- date
- Mon, 10 Jun 2013 17:08:11 +0900
- changeset 8391
- f8ed09648c85
- parent 8387
- f257ff301ad8
- child 8397
- 8b231a13093c
- permissions
- -rw-r--r--
[css3-fonts] font matching editorial fixups and better definition of unicode-range matching
1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
4 <html lang=en>
5 <head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
7 <title>CSS Fonts Module Level 3</title>
8 <!--
9 FIXME when publishing: copy the current default.css and link to
10 "default.css" rather than "../default.css"
11 -->
12 <link href="../default.css" rel=stylesheet type="text/css">
13 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
14 <!-- I'm just experimenting here, don't get your bee in a bonnet -->
15 <script src="http://use.typekit.com/xon2bky.js"
16 type="text/javascript"></script>
17 <script type="text/javascript">try{Typekit.load();}catch(e){}</script>
19 <style type="text/css">
21 body, th, td, h1, h2, h3, h4, h5, h6 {
22 font-family: "myriad-pro", sans-serif !important;
23 }
25 body {
26 padding: 2em 70px 2em 70px;
27 }
29 p + p, p.mtb {
30 margin-top: 0.8em;
31 text-indent: 0px;
32 }
34 #bolderlighter {
35 width: 40%;
36 }
38 #bolderlighter th {
39 text-align: center;
40 }
42 #fontformats td, #eventhandlers td, #fontformats th, #eventhandlers th {
43 padding-right: 2em;
44 text-align: left;
45 }
47 dd {
48 margin-bottom: 1em;
49 }
51 #authors dd {
52 margin-bottom: 0;
53 }
55 #fontstylematchingalg {
56 list-style-type: lower-alpha;
57 }
59 #fontmatchingalg ul, #fontmatchingalg ol {
60 margin-top: 0.8em;
61 }
63 #fontmatchingalg li + li {
64 margin-top: 0.8em;
65 }
67 div.example {
68 padding: 1em;
69 margin-top: 1em;
70 }
72 div.example + div.example {
73 margin-top: 2em;
74 }
76 div.figure {
77 page-break-inside: avoid;
78 }
80 pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
82 div.featex {
83 width: 700px;
84 }
86 div.featex img {
87 margin: auto;
88 display: block;
89 }
91 span.tag {
92 font-family: monospace;
93 font-size: 120%;
94 }
96 ol ol {
97 list-style-type: lower-alpha;
98 }
100 .idl-code {
101 font-weight: bold;
102 color: #c50;
103 }
104 </style>
105 <link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
106 type="text/css">
107 <script defer=defer
108 src="http://test.csswg.org/harness/annotate.js#CSS3-FONTS_DEV"
109 type="text/javascript"></script>
111 <body>
112 <div class=head> <!--begin-logo-->
113 <p><a href="http://www.w3.org/"><img alt=W3C height=48
114 src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
116 <h1>CSS Fonts Module Level 3</h1>
118 <h2 class="no-num no-toc" id=editors-draft-10-june-2013>Editor's Draft 10
119 June 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-css3-fonts-20130610/">http://www.w3.org/TR/2013/ED-css3-fonts-20130610/</a> -->
129 <dt>Latest version:
131 <dd><a
132 href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</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-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</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/css3-font-load-events/">CSS3 Font
199 Load 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>
250 <p>This draft is a <strong>Last Call Working Draft</strong>. Please send
251 comments to the <a
252 href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing
253 list</a> as described above. The <strong>deadline for comments</strong> is
254 six weeks after the date of publication in the header.
256 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
257 <!--begin-toc-->
259 <ul class=toc>
260 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
262 <li><a href="#typography-background"><span class=secno>2 </span>Typography
263 Background</a>
265 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
266 Properties</a>
267 <ul class=toc>
268 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
269 family: the font-family property</a>
270 <ul class=toc>
271 <li><a href="#generic-font-families"><span class=secno>3.1.1
272 </span>Generic font families</a>
273 </ul>
275 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
276 weight: the font-weight property</a>
278 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
279 width: the font-stretch property</a>
281 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
282 the font-style property</a>
284 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
285 the font-size property</a>
287 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
288 </span>Relative sizing: the font-size-adjust property</a>
290 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
291 property: the font property</a>
293 <li><a href="#font-synthesis-prop"><span class=secno>3.8
294 </span>Controlling synthetic faces: the font-synthesis property</a>
295 </ul>
297 <li><a href="#font-resources"><span class=secno>4 </span>Font
298 Resources</a>
299 <ul class=toc>
300 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
301 <code>@font-face</code> rule</a>
303 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
304 family: the font-family descriptor</a>
306 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
307 src descriptor</a>
309 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
310 descriptors: the font-style, font-weight, font-stretch descriptors</a>
312 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
313 range: the unicode-range descriptor</a>
315 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
316 character ranges to define composite fonts</a>
318 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
319 features: the font-variant and font-feature-settings descriptors</a>
321 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
322 loading guidelines</a>
324 <li><a href="#same-origin-restriction"><span class=secno>4.9
325 </span>Same-origin restriction for fonts</a>
326 <ul class=toc>
327 <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
328 </span>Default same-origin restriction</a>
330 <li><a href="#allowing-cross-origin-font-loading"><span
331 class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
332 </ul>
333 </ul>
335 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
336 Matching Algorithm</a>
337 <ul class=toc>
338 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
339 sensitivity of font family names</a>
341 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
342 font styles</a>
344 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
345 matching</a>
347 <li><a href="#char-handling-issues"><span class=secno>5.4
348 </span>Character handling issues</a>
350 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
351 matching changes since CSS 2.1</a>
353 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
354 matching examples</a>
355 </ul>
357 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
358 Properties</a>
359 <ul class=toc>
360 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
361 </span>Glyph selection and positioning</a>
363 <li><a href="#language-specific-support"><span class=secno>6.2
364 </span>Language-specific display</a>
366 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
367 the font-kerning property</a>
369 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
370 </span>Ligatures: the font-variant-ligatures property</a>
372 <li><a href="#font-variant-position-prop"><span class=secno>6.5
373 </span>Subscript and superscript forms: the font-variant-position
374 property</a>
376 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
377 </span>Capitalization: the font-variant-caps property</a>
379 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
380 </span>Numerical formatting: the font-variant-numeric property</a>
382 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
383 </span>Alternates and swashes: the font-variant-alternates property</a>
386 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
387 font specific alternates: the <code>@font-feature-values</code>
388 rule</a>
389 <ul class=toc>
390 <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
391 syntax</a>
393 <li><a href="#multi-valued-feature-value-definitions"><span
394 class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
395 </ul>
397 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
398 </span>East Asian text rendering: the font-variant-east-asian
399 property</a>
401 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
402 shorthand for font rendering: the font-variant property</a>
404 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
405 </span>Low-level font feature settings control: the
406 font-feature-settings property</a>
408 <li><a href="#font-language-override-prop"><span class=secno>6.13
409 </span>Font language override: the font-language-override property</a>
410 </ul>
412 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
413 Feature Resolution </a>
414 <ul class=toc>
415 <li><a href="#default-features"><span class=secno>7.1 </span>Default
416 features</a>
418 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
419 precedence</a>
421 <li><a href="#feature-precedence-examples"><span class=secno>7.3
422 </span>Feature precedence examples</a>
423 </ul>
425 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
426 <ul class=toc>
427 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
428 <code>CSSFontFaceRule</code> interface</a>
430 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
431 <code>CSSFontFeatureValuesRule</code> interface</a>
432 </ul>
434 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
435 platform font properties to CSS properties</a>
437 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
438 <ul class=toc>
439 <li class=no-num><a href="#recent-changes"> Changes from the February
440 2013 CSS3 Fonts Working Draft</a>
441 </ul>
443 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
445 <li class=no-num><a href="#conformance"> Conformance</a>
446 <ul class=toc>
447 <li class=no-num><a href="#conventions"> Document Conventions</a>
449 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
452 <li class=no-num><a href="#partial"> Partial Implementations</a>
454 <li class=no-num><a href="#experimental"> Experimental
455 Implementations</a>
457 <li class=no-num><a href="#testing"> Non-Experimental
458 Implementations</a>
459 </ul>
461 <li class=no-num><a href="#references">References</a>
462 <ul class=toc>
463 <li class=no-num><a href="#normative-references">Normative
464 References</a>
466 <li class=no-num><a href="#other-references">Other References</a>
467 </ul>
469 <li class=no-num><a href="#index">Index</a>
471 <li class=no-num><a href="#property-index">Property index</a>
472 </ul>
473 <!--end-toc-->
475 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
477 <p>A font provides a resource containing the visual representation of
478 characters. At the simplest level it contains information that maps
479 character codes to shapes (called glyphs) that represent these characters.
480 Fonts sharing a common design style are commonly grouped into font
481 families classified by a set of standard font properties. Within a family,
482 the shape displayed for a given character can vary by stroke weight, slant
483 or relative width, among others. An individual font face is described by a
484 unique combination of these properties. For a given range of text, CSS
485 font properties are used to select a font family and a specific font face
486 within that family to be used when rendering that text. As a simple
487 example, to use the bold form of Helvetica one could use:
489 <pre>body {
490 font-family: Helvetica;
491 font-weight: bold;
492 }</pre>
494 <p>Font resources may be installed locally on the system on which a user
495 agent is running or downloadable. For local font resources descriptive
496 information can be obtained directly from the font resource. For
497 downloadable font resources (sometimes referred to as web fonts), the
498 descriptive information is included with the reference to the font
499 resource.
501 <p>Families of fonts typically don't contain a single face for each
502 possible variation of font properties. The CSS font selection mechanism
503 describes how to match a given set of CSS font properties to a single font
504 face.
506 <h2 id=typography-background><span class=secno>2 </span>Typography
507 Background</h2>
509 <p><em>This section is non-normative.</em>
511 <p> Typographic traditions vary across the globe, so there is no unique way
512 to classify all fonts across languages and cultures. For even common Latin
513 letters, wide variations are possible:
515 <div class=figure><img alt="variations in glyphs for a single character"
516 src=aaaaaa.png>
517 <p class=caption>One character, many glyph variations
518 </div>
520 <p>Differences in the anatomy of letterforms is one way to distinguish
521 fonts. For Latin fonts, flourishes at the ends of a character's main
522 strokes, or serifs, can distinguish a font from those without. Similar
523 comparisons exist in non-Latin fonts between fonts with tapered strokes
524 and those using primarily uniform strokes:
526 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
527 <p class=caption>Letterforms with and without serifs
528 </div>
530 <div class=figure><img alt="serif vs. non-serifs for japanese"
531 src=minchovsgothic.png>
532 <p class=caption>Similar groupings for Japanese typefaces
533 </div>
535 <p>Fonts contain letterforms and the data needed to map characters to these
536 letterforms. Often this may be a simple one-to-one mapping, but more
537 complex mappings are also possible. The use of combining diacritic marks
538 creates many variations for an underlying letterform:
540 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
541 <p class=caption>Variations with diacritic marks
542 </div>
544 <p>A sequence of characters can be represented by a single glyph known as a
545 ligature:
547 <div class=figure><img alt="example of a fi ligature"
548 src=final-ligature.png>
549 <p class=caption>Ligature example
550 </div>
552 <p>Visual transformations based on textual context are often stylistic
553 option in European languages. They are required to correctly render
554 languages like Arabic, the lam and alef characters below <em>must</em> be
555 combined when they exist in sequence:
557 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
558 <p class=caption>Required Arabic ligature
559 </div>
561 <p>The relative complexity of these shaping transformations requires
562 additional data within the font.
564 <p>Sets of font faces with various stylistic variations are often grouped
565 together into font families. In the simplest case a regular face is
566 supplemented with bold and italic faces, but much more extensive groupings
567 are possible. Variations in the thickness of letterform strokes, the <dfn
568 id=weight>weight</dfn>, and the overall proportions of the letterform, the
569 <dfn id=width>width</dfn>, are most common. In the example below, each
570 letter uses a different font face within the Univers font family. The
571 width used increases from top to bottom and the weight increases from left
572 to right:
574 <div class=figure><img alt="various width and weight variations within a
575 single family" src=weightwidthvariations.png>
576 <p class=caption>Weight and width variations within a single font family
577 </div>
579 <p>Creating fonts that support multiple scripts is a difficult task;
580 designers need to understand the cultural traditions surrounding the use
581 of type in different scripts and come up with letterforms that somehow
582 share a common theme. Many languages often share a common script and each
583 of these languages may have noticeable stylistic differences. For example,
584 the Arabic script is shared by Persian and Urdu and Cyrillic is used with
585 many languages, not just Russian.
587 <p>The <a href="#character-map"><em>character map</em></a> of a font
588 defines the mapping of characters to glyphs for that font. If a document
589 contains characters not supported by the <a href="#character-map"><em
590 title="character map">character maps</em></a> of the fonts contained in a
591 font family list, a user agent may use a <a
592 href="#system-font-fallback"><em>system font fallback</em></a> procedure
593 to locate an appropriate font that does. If no appropriate font can be
594 found, some form of "missing glyph" character will be rendered by the user
595 agent. System fallback can occur when the specified list of font families
596 does not include a font that supports a given character.
598 <p>Although the <a href="#character-map"><em>character map</em></a> of a
599 font maps a given character to a glyph for that character, modern font
600 technologies such as OpenType and AAT (Apple Advanced Typography) provide
601 ways of mapping a character to different glyphs based upon feature
602 settings. Fonts in these formats allow these features to be embedded in
603 the font itself and controlled by applications. Common typographic
604 features which can be specified this way include ligatures, swashes,
605 contextual alternates, proportional and tabular figures, and automatic
606 fractions, to list just a few. For a visual overview of OpenType features,
607 see the <a href="#OPENTYPE-FONT-GUIDE"
608 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
610 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
612 <p>The particular font face used to render a character is determined by the
613 font family and other font properties that apply to a given element. This
614 structure allows settings to be varied independent of each other.</p>
615 <!-- prop: font-family -->
617 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
618 href="#propdef-font-family">font-family</a> property</h3>
620 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
621 <tbody>
622 <tr>
623 <td>Name:
625 <td><dfn id=propdef-font-family
626 title="font-family!!property">font-family</dfn>
628 <tr>
629 <td>Value:
631 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
632 <a href="#generic-family-value"><var><generic-family></var></a> ]
633 #
635 <tr>
636 <td>Initial:
638 <td>depends on user agent
640 <tr>
641 <td>Applies to:
643 <td>all elements
645 <tr>
646 <td>Inherited:
648 <td>yes
650 <tr>
651 <td>Percentages:
653 <td>N/A
655 <tr>
656 <td>Media:
658 <td>visual
660 <tr>
661 <td>Computed value:
663 <td>as specified
665 <tr>
666 <td>Animatable:
668 <td>no
669 </table>
671 <p>This property specifies a prioritized list of font family names or
672 generic family names. A font family defines a set of faces that vary in
673 weight, width or slope. CSS uses the combination of a family name with
674 other style attributes to select an individual face. Using this selection
675 mechanism, rather than selecting a face via the style name as is often
676 done in design applications, allows some degree of regularity in textual
677 display when fallback occurs.
679 <p class=note>Designers should note that the CSS definition of font
680 attributes used for selection are explicitly not intended to define a font
681 taxonomy. A type designer's idea of a family may often extend to a set of
682 faces that vary along axes other than just the standard axes of weight,
683 width and slope. A family may extend to include both a set of serif faces
684 and a set of sans-serif faces or vary along axes that are unique to that
685 family. The CSS font selection mechanism merely provides a way to
686 determine the “closest” substitute when substitution is necessary.
688 <p>Unlike other CSS properties, component values are a comma-separated list
689 indicating alternatives. A user agent iterates through the list of family
690 names until it matches an available font that contains a glyph for the
691 character to be rendered. This allows for differences in available fonts
692 across platforms and for differences in the range of characters supported
693 by individual fonts.
695 <p>A font family name only specifies a name given to a set of font faces,
696 it does not specify an individual face. For example, given the
697 availability of the fonts below, Futura would match but Futura Medium
698 would not:
700 <div class=figure><img alt="family and face names"
701 src=familyvsfacename.png>
702 <p class=caption>Family and individual face names
703 </div>
705 <p>Consider the example below:
707 <div class=example>
708 <pre>body {
709 font-family: Helvetica, Verdana, sans-serif;
710 }</pre>
712 <p>If Helvetica is available it will be used when rendering. If neither
713 Helvetica nor Verdana is present, then the user-agent-defined sans serif
714 font will be used.</p>
715 </div>
717 <p>There are two types of font family names:
719 <dl>
720 <dt><dfn id=family-name-value><var><family-name></var></dfn>
722 <dd>The name of a font family of choice such as Helvetica or Verdana in
723 the previous example.
725 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
727 <dd> The following generic family keywords are defined: ‘<a
728 href="#serif"><code class=property>serif</code></a>’, ‘<a
729 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
730 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
731 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
732 href="#monospace"><code class=property>monospace</code></a>’. These
733 keywords can be used as a general fallback mechanism when an author's
734 desired font choices are not available. As keywords, they must not be
735 quoted. Authors are encouraged to append a generic font family as a last
736 alternative for improved robustness.
737 </dl>
739 <p>Font family names other than generic families must either be given
740 quoted as <a
741 href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
742 as a sequence of one or more <a
743 href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
744 This means most punctuation characters and digits at the start of each
745 token must be escaped in unquoted font family names.
747 <p>To illustrate this, the following declarations are invalid:
749 <pre>
750 font-family: Red/Black, sans-serif;
751 font-family: "Lucida" Grande, sans-serif;
752 font-family: Ahem!, sans-serif;
753 font-family: test@foo, sans-serif;
754 font-family: #POUND, sans-serif;
755 font-family: Hawaii 5-0, sans-serif;
756 </pre>
758 <p>If a sequence of identifiers is given as a font family name, the
759 computed value is the name converted to a string by joining all the
760 identifiers in the sequence by single spaces.
762 <p>To avoid mistakes in escaping, it is recommended to quote font family
763 names that contain white space, digits, or punctuation characters other
764 than hyphens:
766 <pre>
767 body { font-family: "New Century Schoolbook", serif }
769 <BODY STYLE="font-family: '21st Century', fantasy">
770 </pre>
772 <p>Font family <em>names</em> that happen to be the same as a keyword value
773 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
774 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
775 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
776 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
777 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
778 class=property>cursive</code></a>’) must be quoted to prevent confusion
779 with the keywords with the same names. The keywords ‘<code
780 class=property>initial</code>’ and ‘<code
781 class=property>default</code>’ are reserved for future use and must also
782 be quoted when used as font names. UAs must not consider these keywords as
783 matching the <a
784 href="#family-name-value"><var><family-name></var></a> type.
786 <p>The precise way a set of fonts are grouped into font families varies
787 depending upon the platform font management API's. The Windows GDI API
788 only allows four faces to be grouped into a family while the DirectWrite
789 API and API's on OSX and other platforms support font families with a
790 variety of weights, widths and slopes (see <a
791 href="#platform-props-to-css">Appendix A</a> for more details).
793 <p>Some font formats allow fonts to carry multiple localizations of the
794 family name. User agents must recognize and correctly match all of these
795 names independent of the underlying platform localization, system API used
796 or document encoding:
798 <div class=figure><img alt="examples of localized family names"
799 src=localizedfamilynames.png>
800 <p class=caption>Localized family names
801 </div>
803 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
804 families</h4>
806 <p>All five generic font families are defined to exist in all CSS
807 implementations (they need not necessarily map to five distinct actual
808 fonts). User agents should provide reasonable default choices for the
809 generic font families, which express the characteristics of each family as
810 well as possible within the limits allowed by the underlying technology.
811 User agents are encouraged to allow users to select alternative choices
812 for the generic fonts.
814 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
815 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
817 <p>Serif fonts represent the formal text style for a script. This often
818 means but is not limited to glyphs that have finishing strokes, flared or
819 tapering ends, or have actual serifed endings (including slab serifs).
820 Serif fonts are typically proportionately-spaced. They often display a
821 greater variation between thick and thin strokes than fonts from the ‘<a
822 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
823 font family. CSS uses the term ‘<a href="#serif"><code
824 class=property>serif</code></a>’ to apply to a font for any script,
825 although other names may be more familiar for particular scripts, such as
826 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
827 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
828 class=property>serif</code></a>’ more due to its typographic role rather
829 than its actual design style. Any font that is so described may be used to
830 represent the generic ‘<a href="#serif"><code
831 class=property>serif</code></a>’ family.
833 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
834 <p class=caption>Sample serif fonts
835 </div>
837 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
838 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
839 id=sans-serif>sans-serif</dfn></a></span></h5>
841 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
842 low contrast (vertical and horizontal stems have the close to the same
843 thickness) and have stroke endings that are plain -- without any flaring,
844 cross stroke, or other ornamentation. Sans-serif fonts are typically
845 proportionately-spaced. They often have little variation between thick and
846 thin strokes, compared to fonts from the ‘<a href="#serif"><code
847 class=property>serif</code></a>’ family. CSS uses the term ‘<a
848 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
849 to a font for any script, although other names may be more familiar for
850 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
851 (Korean). Any font that is so described may be used to represent the
852 generic ‘<a href="#sans-serif"><code
853 class=property>sans-serif</code></a>’ family.
855 <div class=figure><img alt="sample sans-serif fonts"
856 src=sansserifexamples.png>
857 <p class=caption>Sample sans-serif fonts
858 </div>
860 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
861 title="cursive, definition of"> <a name=cursive-def><dfn
862 id=cursive>cursive</dfn></a></span></h5>
864 <p>Glyphs in cursive fonts generally use a more informal script style, and
865 the result looks more like handwritten pen or brush writing than printed
866 letterwork. CSS uses the term ‘<a href="#cursive"><code
867 class=property>cursive</code></a>’ to apply to a font for any script,
868 although other names such as Chancery, Brush, Swing and Script are also
869 used in font names.
871 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
872 <p class=caption>Sample cursive fonts
873 </div>
875 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
876 title="fantasy, definition of"> <a name=fantasy-def><dfn
877 id=fantasy>fantasy</dfn></a></span></h5>
879 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
880 playful representations of characters. These do not include Pi or Picture
881 fonts which do not represent actual characters.
883 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
884 <p class=caption>Sample fantasy fonts
885 </div>
887 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
888 title="monospace, definition of"> <a name=monospace-def><dfn
889 id=monospace>monospace</dfn></a></span></h5>
891 <p>The sole criterion of a monospace font is that all glyphs have the same
892 fixed width. This is often used to render samples of computer code.
894 <div class=figure><img alt="sample monospace fonts"
895 src=monospaceexamples.png>
896 <p class=caption>Sample monospace fonts
897 </div>
898 <!-- prop: font-weight -->
900 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
901 href="#propdef-font-weight">font-weight</a> property</h3>
903 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
904 <tbody>
905 <tr>
906 <td>Name:
908 <td><dfn id=propdef-font-weight
909 title="font-weight!!property">font-weight</dfn>
911 <tr>
912 <td>Value:
914 <td><a href="#font-weight-normal-value"
915 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
916 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
917 href="#font-weight-numeric-values" title="100...900 weight
918 values">100</a> | <a href="#font-weight-numeric-values"
919 title="100...900 weight values">200</a> | <a
920 href="#font-weight-numeric-values" title="100...900 weight
921 values">300</a> | <a href="#font-weight-numeric-values"
922 title="100...900 weight values">400</a> | <a
923 href="#font-weight-numeric-values" title="100...900 weight
924 values">500</a> | <a href="#font-weight-numeric-values"
925 title="100...900 weight values">600</a> | <a
926 href="#font-weight-numeric-values" title="100...900 weight
927 values">700</a> | <a href="#font-weight-numeric-values"
928 title="100...900 weight values">800</a> | <a
929 href="#font-weight-numeric-values" title="100...900 weight
930 values">900</a>
932 <tr>
933 <td>Initial:
935 <td>normal
937 <tr>
938 <td>Applies to:
940 <td>all elements
942 <tr>
943 <td>Inherited:
945 <td>yes
947 <tr>
948 <td>Percentages:
950 <td>N/A
952 <tr>
953 <td>Media:
955 <td>visual
957 <tr>
958 <td>Computed value:
960 <td>numeric weight value (see description)
962 <tr>
963 <td>Animatable:
965 <td>as <a
966 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
967 weight</a>
968 </table>
970 <p>The <a href="#propdef-font-weight"
971 title="font-weight!!property">‘<code
972 class=property>font-weight</code>’</a> property specifies the weight of
973 glyphs in the font, their degree of blackness or stroke thickness.
975 <p>Values have the following meanings:
977 <dl>
978 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
979 to 900</dfn>
981 <dd>These values form an ordered sequence, where each number indicates a
982 weight that is at least as dark as its predecessor. These roughly
983 correspond to the commonly used weight names below:
984 </dl>
986 <ul>
987 <li>100 - Thin
989 <li>200 - Extra Light (Ultra Light)
991 <li>300 - Light
993 <li>400 - Normal
995 <li>500 - Medium
997 <li>600 - Semi Bold (Demi Bold)
999 <li>700 - Bold
1001 <li>800 - Extra Bold (Ultra Bold)
1003 <li>900 - Black (Heavy)
1004 </ul>
1006 <dl>
1007 <dt><dfn id=font-weight-normal-value
1008 title="normal!!font-weight">normal</dfn>
1010 <dd>Same as ‘<code class=css>400</code>’.
1012 <dt><dfn id=bold>bold</dfn>
1014 <dd>Same as ‘<code class=css>700</code>’.
1016 <dt><dfn id=bolder>bolder</dfn>
1018 <dd>Specifies a bolder weight than the inherited value.
1020 <dt><dfn id=lighter>lighter</dfn>
1022 <dd>Specifies a lighter weight than the inherited value.
1023 </dl>
1025 <p>Font formats that use a scale other than a nine-step scale should map
1026 their scale onto the CSS scale so that 400 roughly corresponds with a face
1027 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1028 face that would be labeled as Bold. Or weights may be inferred from the
1029 style names, ones that correspond roughly with the scale above. The scale
1030 is relative, so a face with a larger weight value must never appear
1031 lighter. If style names are used to infer weights, care should be taken to
1032 handle variations in style names across locales.
1034 <p>Quite often there are only a few weights available for a particular font
1035 family. When a weight is specified for which no face exists, a face with a
1036 nearby weight is used. In general, bold weights map to faces with heavier
1037 weights and light weights map to faces with lighter weights (see the <a
1038 href="#font-matching-algorithm">font matching section below</a> for a
1039 precise definition). The examples here illustrate which face is used for
1040 different weights, grey indicates a face for that weight does not exist so
1041 a face with a nearby weight is used:
1043 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1044 900 weights" src=optimaweights.png>
1045 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1046 weight faces
1047 </div>
1049 <div class=figure><img alt="weight mappings for a family with 300, 600
1050 weights" src=hiraginoweights.png>
1051 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1052 faces
1053 </div>
1055 <p>Although the practice is not well-loved by typographers, bold faces are
1056 often synthesized by user agents for faces that lack actual bold faces.
1057 For the purposes of style matching, these faces must be treated as if they
1058 exist within the family. Authors can explicitly avoid this behavior by
1059 using the ‘<a href="#propdef-font-synthesis"><code
1060 class=property>font-synthesis</code></a>’ property.
1062 <p>Specified values of ‘<a href="#bolder"><code
1063 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1064 class=property>lighter</code></a>’ indicate weights relative to the
1065 weight of the parent element. The computed weight is calculated based on
1066 the inherited <a href="#propdef-font-weight"
1067 title="font-weight!!property">‘<code
1068 class=property>font-weight</code>’</a> value using the chart below.
1070 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1071 <thead>
1072 <tr>
1073 <th>Inherited value
1075 <th>bolder
1077 <th>lighter
1079 <tbody>
1080 <tr>
1081 <th>100
1083 <td>400
1085 <td>100
1087 <tr>
1088 <th>200
1090 <td>400
1092 <td>100
1094 <tr>
1095 <th>300
1097 <td>400
1099 <td>100
1101 <tr>
1102 <th>400
1104 <td>700
1106 <td>100
1108 <tr>
1109 <th>500
1111 <td>700
1113 <td>100
1115 <tr>
1116 <th>600
1118 <td>900
1120 <td>400
1122 <tr>
1123 <th>700
1125 <td>900
1127 <td>400
1129 <tr>
1130 <th>800
1132 <td>900
1134 <td>700
1136 <tr>
1137 <th>900
1139 <td>900
1141 <td>700
1142 </table>
1144 <p>The table above is equivalent to selecting the next relative bolder or
1145 lighter face, given a font family containing normal and bold faces along
1146 with a thin and a heavy face. Authors who desire finer control over the
1147 exact weight values used for a given element may use numerical values
1148 instead of relative weights.</p>
1149 <!-- prop: font-stretch -->
1151 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1152 href="#propdef-font-stretch">font-stretch</a> property</h3>
1154 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1155 <tbody>
1156 <tr>
1157 <td>Name:
1159 <td><dfn id=propdef-font-stretch
1160 title="font-stretch!!property">font-stretch</dfn>
1162 <tr>
1163 <td>Value:
1165 <td> <a href="#font-stretch-normal-value"
1166 title="normal!!font-stretch">normal</a> | <a
1167 href="#ultra-condensed">ultra-condensed</a> | <a
1168 href="#extra-condensed">extra-condensed</a> | <a
1169 href="#condensed">condensed</a> | <a
1170 href="#semi-condensed-">semi-condensed</a> | <a
1171 href="#semi-expanded">semi-expanded</a> | <a
1172 href="#expanded">expanded</a> | <a
1173 href="#extra-expanded">extra-expanded</a> | <a
1174 href="#ultra-expanded">ultra-expanded</a>
1176 <tr>
1177 <td>Initial:
1179 <td>normal
1181 <tr>
1182 <td>Applies to:
1184 <td>all elements
1186 <tr>
1187 <td>Inherited:
1189 <td>yes
1191 <tr>
1192 <td>Percentages:
1194 <td>N/A
1196 <tr>
1197 <td>Media:
1199 <td>visual
1201 <tr>
1202 <td>Computed value:
1204 <td>as specified
1206 <tr>
1207 <td>Animatable:
1209 <td>as <a href="#font-stretch-animation">font stretch</a>
1210 </table>
1212 <p>The <a href="#propdef-font-stretch"
1213 title="font-stretch!!property">‘<code
1214 class=property>font-stretch</code>’</a> property selects a normal,
1215 condensed, or expanded face from a font family. Absolute keyword values
1216 have the following ordering, from narrowest to widest:
1218 <ul>
1219 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1221 <li><dfn id=extra-condensed>extra-condensed</dfn>
1223 <li><dfn id=condensed>condensed</dfn>
1225 <li><dfn id=semi-condensed->semi-condensed </dfn>
1227 <li><dfn id=font-stretch-normal-value
1228 title="normal!!font-stretch">normal</dfn>
1230 <li><dfn id=semi-expanded>semi-expanded</dfn>
1232 <li><dfn id=expanded>expanded</dfn>
1234 <li><dfn id=extra-expanded>extra-expanded</dfn>
1236 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1237 </ul>
1239 <p>When a face does not exist for a given width, normal or condensed values
1240 map to a narrower face, otherwise a wider face. Conversely, expanded
1241 values map to a wider face, otherwise a narrower face. The figure below
1242 shows how the nine font-stretch property settings affect font selection
1243 for font family containing a variety of widths, grey indicates a width for
1244 which no face exists and a different width is substituted:
1246 <div class=figure><img alt="width mappings for a family with condensed,
1247 normal and expanded faces" src=universwidths.png>
1248 <p class=caption>Width mappings for a font family with condensed, normal
1249 and expanded width faces
1250 </div>
1252 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1253 interpolated in discrete steps. The interpolation happens as though the
1254 ordered values are equally spaced real numbers. The interpolation result
1255 is rounded to the nearest value, with values exactly halfway between two
1256 values rounded towards the later value in the list above.</p>
1257 <!-- prop: font-style -->
1259 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1260 href="#propdef-font-style">font-style</a> property</h3>
1262 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1263 <tbody>
1264 <tr>
1265 <td>Name:
1267 <td><dfn id=propdef-font-style
1268 title="font-style!!property">font-style</dfn>
1270 <tr>
1271 <td>Value:
1273 <td><a href="#font-style-normal-value"
1274 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1275 <a href="#oblique">oblique</a>
1277 <tr>
1278 <td>Initial:
1280 <td>normal
1282 <tr>
1283 <td>Applies to:
1285 <td>all elements
1287 <tr>
1288 <td>Inherited:
1290 <td>yes
1292 <tr>
1293 <td>Percentages:
1295 <td>N/A
1297 <tr>
1298 <td>Media:
1300 <td>visual
1302 <tr>
1303 <td>Computed value:
1305 <td>as specified
1307 <tr>
1308 <td>Animatable:
1310 <td>no
1311 </table>
1313 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1314 class=property>font-style</code>’</a> property allows italic or oblique
1315 faces to be selected. Italic forms are generally cursive in nature while
1316 oblique faces are typically sloped versions of the regular face. Oblique
1317 faces can be simulated by artificially sloping the glyphs of the regular
1318 face. Compare the artificially sloped renderings of Palatino ‘<code
1319 class=property>a</code>’ and Baskerville ‘<code
1320 class=property>N</code>’ in grey with the actual italic versions:
1322 <div class=figure><img alt="artificial sloping vs. real italics"
1323 src=realvsfakeitalics.png>
1324 <p class=caption>Artificial sloping versus real italics
1325 </div>
1327 <p>Values have the following meanings:
1329 <dl>
1330 <dt><dfn id=font-style-normal-value
1331 title="normal!!font-style">normal</dfn>
1333 <dd>selects a face that is classified as a normal face, one that is
1334 neither italic or obliqued
1336 <dt><dfn id=italic>italic</dfn>
1338 <dd>selects a font that is labeled as an italic face, or an oblique face
1339 if one is not
1341 <dt><dfn id=oblique>oblique</dfn>
1343 <dd>selects a font that is labeled as an oblique face, or an italic face
1344 if one is not
1345 </dl>
1347 <p>If no italic or oblique face is available, oblique faces can be
1348 synthesized by rendering non-obliqued faces with an artificial obliquing
1349 operation. The use of these artificially obliqued faces can be disabled
1350 using the ‘<a href="#propdef-font-synthesis"><code
1351 class=property>font-synthesis</code></a>’ property. The details of the
1352 obliquing operation are not explicitly defined.</p>
1353 <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
1355 <p>Many scripts lack the tradition of mixing a cursive form within text
1356 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1357 always lack italic or oblique faces. Fonts that support a mixture of
1358 scripts will sometimes omit specific scripts such as Arabic from the set
1359 of glyphs supported in the italic face. User agents should be careful
1360 about making <a href="#character-map"><em>character map</em></a>
1361 assumptions across faces when implementing support for <a
1362 href="#system-font-fallback"><em>system font fallback</em></a>.</p>
1363 <!-- prop: font-size -->
1365 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1366 href="#propdef-font-size">font-size</a> property</h3>
1368 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1369 <tbody>
1370 <tr>
1371 <td>Name:
1373 <td><dfn id=propdef-font-size>font-size</dfn>
1375 <tr>
1376 <td>Value:
1378 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1379 | <a href="#relative-size-value"><var><relative-size></var></a> |
1380 <a href="#length-size-value"><var><length></var></a> | <a
1381 href="#percentage-size-value"><var><percentage></var></a>
1383 <tr>
1384 <td>Initial:
1386 <td>medium
1388 <tr>
1389 <td>Applies to:
1391 <td>all elements
1393 <tr>
1394 <td>Inherited:
1396 <td>yes
1398 <tr>
1399 <td>Percentages:
1401 <td>refer to parent element's font size
1403 <tr>
1404 <td>Media:
1406 <td>visual
1408 <tr>
1409 <td>Computed value:
1411 <td>absolute length
1413 <tr>
1414 <td>Animatable:
1416 <td>as <a
1417 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1418 </table>
1420 <p>This property indicates the desired height of glyphs from the font. For
1421 scalable fonts, the font-size is a scale factor applied to the EM unit of
1422 the font. (Note that certain glyphs may bleed outside their EM box.) For
1423 non-scalable fonts, the font-size is converted into absolute units and
1424 matched against the declared font-size of the font, using the same
1425 absolute coordinate space for both of the matched values. Values have the
1426 following meanings:
1428 <dl>
1429 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1431 <dd> An <a
1432 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1433 refers to an entry in a table of font sizes computed and kept by the user
1434 agent. Possible values are:
1435 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1437 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1439 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1440 keyword is interpreted relative to the table of font sizes and the
1441 computed ‘<a href="#propdef-font-size"><code
1442 class=property>font-size</code></a>’ of the parent element. Possible
1443 values are:
1444 <p> [ larger | smaller ]
1446 <p> For example, if the parent element has a font size of ‘<code
1447 class=property>medium</code>’, a value of ‘<code
1448 class=property>larger</code>’ will make the font size of the current
1449 element be ‘<code class=property>large</code>’. If the parent
1450 element's size is not close to a table entry, the user agent is free to
1451 interpolate between table entries or round off to the closest one. The
1452 user agent may have to extrapolate table values if the numerical value
1453 goes beyond the keywords.
1455 <dt><dfn id=length-size-value><var><length></var></dfn>
1457 <dd>A length value specifies an absolute font size (independent of the
1458 user agent's font table). Negative lengths are illegal.
1460 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1462 <dd>A percentage value specifies an absolute font size relative to the
1463 parent element's font size. Use of percentage values, or values in
1464 ‘<code class=property>em</code>’s, leads to more robust and
1465 cascadable style sheets.
1466 </dl>
1468 <p>The following table provides user agent guidelines for the absolute-size
1469 scaling factor and their mapping to HTML heading and absolute font-sizes.
1470 The ‘<code class=property>medium</code>’ value is used as the
1471 reference middle value. The user agent may fine-tune these values for
1472 different fonts or different types of display devices.
1474 <table class=data>
1475 <thead>
1476 <tr>
1477 <th>CSS absolute-size values
1479 <th>xx-small
1481 <th>x-small
1483 <th>small
1485 <th>medium
1487 <th>large
1489 <th>x-large
1491 <th>xx-large
1493 <th>
1495 <tbody>
1496 <tr>
1497 <th>scaling factor
1499 <td>3/5
1501 <td>3/4
1503 <td>8/9
1505 <td>1
1507 <td>6/5
1509 <td>3/2
1511 <td>2/1
1513 <td>3/1
1515 <tr>
1516 <th>HTML headings
1518 <td>h6
1520 <td>
1522 <td>h5
1524 <td>h4
1526 <td>h3
1528 <td>h2
1530 <td>h1
1532 <td>
1534 <tr>
1535 <th>HTML font sizes
1537 <td>1
1539 <td>
1541 <td>2
1543 <td>3
1545 <td>4
1547 <td>5
1549 <td>6
1551 <td>7
1552 </table>
1554 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1555 applying these guidelines should nevertheless avoid creating font-size
1556 resulting in less than 9 device pixels per EM unit on a computer
1557 display.</em>
1559 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1560 factor between adjacent indexes was 1.5 which user experience proved to be
1561 too large. In CSS2, the suggested scaling factor for computer screen
1562 between adjacent indexes was 1.2 which still created issues for the small
1563 sizes. The new scaling factor varies between each index to provide a
1564 better readability.</em>
1566 <p>The actual value of this property may differ from the computed value due
1567 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1568 class=property>font-size-adjust</code></a>’ and the unavailability of
1569 certain font sizes.
1571 <p>Child elements inherit the computed <a class=noxref
1572 href="#font-size-prop"> <span class=property>‘<code
1573 class=property>font-size</code>’</span></a> value (otherwise, the effect
1574 of <a class=noxref href="#font-size-adjust-prop"><span
1575 class=property>‘<code
1576 class=property>font-size-adjust</code>’</span></a> would compound).
1578 <div class=example>
1579 <p style="display:none">Example(s):
1581 <p>
1583 <pre>p { font-size: 12pt; }
1584 blockquote { font-size: larger }
1585 em { font-size: 150% }
1586 em { font-size: 1.5em }
1587 </pre>
1588 </div>
1589 <!-- prop: font-size-adjust -->
1591 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1592 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1594 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1595 <tbody>
1596 <tr>
1597 <td>Name:
1599 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1601 <tr>
1602 <td>Value:
1604 <td><a href="#font-size-adjust-none-value"
1605 title="none!!font-size-adjust">none</a> | <a
1606 href="#font-size-adjust-auto-value"
1607 title="auto!!font-size-adjust">auto</a> | <a
1608 href="#aspect-ratio-value"><var><number></var></a>
1610 <tr>
1611 <td>Initial:
1613 <td>none
1615 <tr>
1616 <td>Applies to:
1618 <td>all elements
1620 <tr>
1621 <td>Inherited:
1623 <td>yes
1625 <tr>
1626 <td>Percentages:
1628 <td>N/A
1630 <tr>
1631 <td>Media:
1633 <td>visual
1635 <tr>
1636 <td>Computed value:
1638 <td>as specified
1640 <tr>
1641 <td>Animatable:
1643 <td>as <a
1644 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1645 </table>
1647 <p>For any given font size, the apparent size and legibility of text varies
1648 across fonts. For scripts such as Latin or Cyrillic that distinguish
1649 between upper and lowercase letters, the relative height of lowercase
1650 letters compared to their uppercase counterparts is a determining factor
1651 of legibility. This is commonly referred to as the <a class=index-def
1652 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1653 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1654 the x-height of a font divided by the font size.
1656 <p>In situations where font fallback occurs, fallback fonts may not share
1657 the same aspect ratio as the desired font family and will thus appear less
1658 readable. The font-size-adjust property is a way to preserve the
1659 readability of text when font fallback occurs. It does this by adjusting
1660 the font-size so that the x-height is the same regardless of the font
1661 used.
1663 <div class=example>
1664 <p>The style defined below defines Verdana as the desired font family, but
1665 if Verdana is not available Futura or Times will be used.</p>
1667 <pre>p {
1668 font-family: Verdana, Futura, Times;
1669 }
1671 <p>Lorem ipsum dolor sit amet, ...</p>
1672 </pre>
1674 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1675 relatively tall compared to uppercase letters, so at small sizes text
1676 appears legible. Times has a lower aspect ratio and so if fallback
1677 occurs, the text will be less legible at small sizes than Verdana.</p>
1678 </div>
1680 <p>How text rendered in each of these fonts compares is shown below, the
1681 columns show text rendered in Verdana, Futura and Times. The same
1682 font-size value is used across cells within each row and red lines are
1683 included to show the differences in x-height. In the upper half each row
1684 is rendered in the same font-size value. The same is true for the lower
1685 half but in this half the font-size-adjust property is also set so that
1686 the actual font size is adjusted to preserve the x-height across each row.
1687 Note how small text remains relatively legible across each row in the
1688 lower half.
1690 <div class=figure><img alt="text with and without font-size-adjust"
1691 src=fontsizeadjust.png>
1692 <p class=caption>Text with and without the use of font-size-adjust
1693 </div>
1695 <p>This property allows authors to specify an aspect value for an element
1696 that will effectively preserve the x-height of the first choice font,
1697 whether it is substituted or not. Values have the following meanings:
1699 <dl>
1700 <dt><dfn id=font-size-adjust-none-value
1701 title="none!!font-size-adjust">none</dfn>
1703 <dd>Do not preserve the font's x-height.
1705 <dt><dfn id=font-size-adjust-auto-value
1706 title="auto!!font-size-adjust">auto</dfn>
1708 <dd>Behaves just like <number>, except the number used is the aspect
1709 value calculated by user agents for the first font in the list of fonts
1710 defined for the initial value of the <a href="#propdef-font-family"
1711 title="font-family!!property">‘<code
1712 class=property>font-family</code>’</a> property. Effectively this is
1713 the default font used when <a href="#propdef-font-family"
1714 title="font-family!!property">‘<code
1715 class=property>font-family</code>’</a> is not otherwise specified.
1716 <p>Authors can use this value to specify that font size should be
1717 normalized across fonts based on the x-height without the need to
1718 specify the aspect ratio explicitly.</p>
1720 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1722 <dd>Specifies the aspect value used in the calculation below to calculate
1723 the adjusted font size:
1724 <pre>c = ( a / a' ) s
1725 </pre>
1727 <p>where:</p>
1729 <pre>s = font-size value
1730 a = aspect value as specified by the font-size-adjust property
1731 a' = aspect value of actual font
1732 c = adjusted font-size to use
1733 </pre>
1735 <p>This value applies to any font that is selected but in typical usage
1736 it should be based on the aspect value of the first font in the
1737 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1738 term in the formula above is effectively 1 for the first font and no
1739 adjustment occurs. If the value is specified inaccurately, text rendered
1740 using the first font in the family list will display differently in
1741 older user agents that don't support font-size-adjust.</p>
1742 </dl>
1744 <p>Authors can calculate the aspect value for a given font by comparing
1745 spans with the same content but different font-size-adjust properties. If
1746 the same font-size is used, the spans will match when the font-size-adjust
1747 value is accurate for the given font.
1749 <div class=example>
1750 <p>Two spans with borders are used to determine the aspect value of a
1751 font. The font-size is the same for both spans but the font-size-adjust
1752 property is specified only for the right span. Starting with a value of
1753 0.5, the aspect value can be adjusted until the borders around the two
1754 letters line up.</p>
1756 <pre>p {
1757 font-family: Futura;
1758 font-size: 500px;
1759 }
1761 span {
1762 border: solid 1px red;
1763 }
1765 .adjust {
1766 font-size-adjust: 0.5;
1767 }
1769 <p><span>b</span><span class="adjust">b</span></p>
1770 </pre>
1772 <div class=figure><img alt="Futura with an aspect value of 0.5"
1773 src=beforefontsizeadjust.png>
1774 <p class=caption>Futura with an aspect value of 0.5
1775 </div>
1777 <p>The box on the right is a bit bigger than the one on the left, so the
1778 aspect value of this font is something less than 0.5. Adjust the value
1779 until the boxes align.</p>
1780 </div>
1781 <!-- prop: font -->
1783 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1784 <a href="#propdef-font">font</a> property</h3>
1786 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1787 <tbody>
1788 <tr>
1789 <td>Name:
1791 <td><dfn id=propdef-font>font</dfn>
1793 <tr>
1794 <td>Value:
1796 <td>[ [ <var><<a href="#propdef-font-style"
1797 title="font-style!!property">‘<code
1798 class=property>font-style</code>’</a>></var> || <a
1799 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1800 || <var><<a href="#propdef-font-weight"
1801 title="font-weight!!property">‘<code
1802 class=property>font-weight</code>’</a>></var> || <var><<a
1803 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1804 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1805 href="#propdef-font-size"><code
1806 class=property>font-size</code></a>’></var> [ / <var><‘<code
1807 class=property>line-height</code>’></var> ]? <var><<a
1808 href="#propdef-font-family" title="font-family!!property">‘<code
1809 class=property>font-family</code>’</a>></var> ] | caption | icon |
1810 menu | message-box | small-caption | status-bar
1812 <tr>
1813 <td>Initial:
1815 <td>see individual properties
1817 <tr>
1818 <td>Applies to:
1820 <td>all elements
1822 <tr>
1823 <td>Inherited:
1825 <td>yes
1827 <tr>
1828 <td>Percentages:
1830 <td>see individual properties
1832 <tr>
1833 <td>Media:
1835 <td>visual
1837 <tr>
1838 <td>Computed value:
1840 <td>see individual properties
1842 <tr>
1843 <td>Animatable:
1845 <td>see individual properties
1846 </table>
1848 <p>The <span class=property>‘<a href="#propdef-font"><code
1849 class=property>font</code></a>’</span> property is, except as described
1850 below, a shorthand property for setting <a href="#propdef-font-style"
1851 title="font-style!!property">‘<code
1852 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1853 title="font-variant!!property">‘<code
1854 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1855 title="font-weight!!property">‘<code
1856 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1857 title="font-stretch!!property">‘<code
1858 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1859 href="#propdef-font-size"><code
1860 class=property>font-size</code></a>’</span>, <a class=property
1861 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1862 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1863 title="font-family!!property">‘<code
1864 class=property>font-family</code>’</a> at the same place in the
1865 stylesheet. Values for the <a href="#propdef-font-variant"
1866 title="font-variant!!property">‘<code
1867 class=property>font-variant</code>’</a> property may also be included
1868 but only those supported in CSS 2.1, none of the <a
1869 href="#propdef-font-variant" title="font-variant!!property">‘<code
1870 class=property>font-variant</code>’</a> values added in this
1871 specification can be used in the <span class=property>‘<a
1872 href="#propdef-font"><code class=property>font</code></a>’</span>
1873 shorthand:
1875 <pre
1876 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1878 <p>The syntax of this property is based on a traditional typographical
1879 shorthand notation to set multiple properties related to fonts.
1881 <p>All subproperties of the ‘<a href="#propdef-font"><code
1882 class=property>font</code></a>’ property are first reset to their
1883 initial values, including those listed above plus <span
1884 class=property>‘<a href="#propdef-font-size-adjust"><code
1885 class=property>font-size-adjust</code></a>’</span>, <span
1886 class=property>‘<a href="#propdef-font-kerning"><code
1887 class=property>font-kerning</code></a>’</span>, subproperties of <a
1888 href="#propdef-font-variant" title="font-variant!!property">‘<code
1889 class=property>font-variant</code>’</a> and and <span>‘<a
1890 href="#propdef-font-language-override"><code
1891 class=property>font-language-override</code></a>’</span>. Then, those
1892 properties that are given explicit values in the <span
1893 class=property>‘<a href="#propdef-font"><code
1894 class=property>font</code></a>’</span> shorthand are set to those
1895 values. For a definition of allowed and initial values, see the previously
1896 defined properties. For reasons of backwards compatibility, it is not
1897 possible to set <span class=property>‘<a
1898 href="#propdef-font-size-adjust"><code
1899 class=property>font-size-adjust</code></a>’</span> to anything other
1900 than its initial value using the <span class=property>‘<a
1901 href="#propdef-font"><code class=property>font</code></a>’</span>
1902 shorthand property; instead, use the individual property.
1904 <div class=example>
1905 <p style="display:none">Example(s):
1907 <p>
1909 <pre>p { font: 12pt/14pt sans-serif }
1910 p { font: 80% sans-serif }
1911 p { font: x-large/110% "new century schoolbook", serif }
1912 p { font: bold italic large Palatino, serif }
1913 p { font: normal small-caps 120%/120% fantasy }
1914 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1915 </pre>
1917 <p> In the second rule, the font size percentage value (‘<code
1918 class=css>80%</code>’) refers to the computed ‘<a
1919 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1920 the parent element. In the third rule, the line height percentage
1921 (‘<code class=css>110%</code>’) refers to the font size of the
1922 element itself.
1924 <p>The first three rules do not specify the <a
1925 href="#propdef-font-variant" title="font-variant!!property">‘<code
1926 class=property>font-variant</code>’</a> and <a
1927 href="#propdef-font-weight" title="font-weight!!property">‘<code
1928 class=property>font-weight</code>’</a> explicitly, so these properties
1929 receive their initial values (<span title="normal value">‘<code
1930 class=property>normal</code>’</span>). Notice that the font family name
1931 "new century schoolbook", which contains spaces, is enclosed in quotes.
1932 The fourth rule sets the <a href="#propdef-font-weight"
1933 title="font-weight!!property">‘<code
1934 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1935 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1936 title="font-style!!property">‘<code
1937 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1938 class=property>italic</code></a>’, and implicitly sets <a
1939 href="#propdef-font-variant" title="font-variant!!property">‘<code
1940 class=property>font-variant</code>’</a> to <a
1941 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1942 class=property>normal</code>’</a>.
1944 <p> The fifth rule sets the <a href="#propdef-font-variant"
1945 title="font-variant!!property">‘<code
1946 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1947 class=property>small-caps</code></a>’), the <span class=property>‘<a
1948 href="#propdef-font-size"><code
1949 class=property>font-size</code></a>’</span> (120% of the parent's font
1950 size), the <a class=property
1951 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1952 class=property>line-height</code>’</a> (120% of the font size) and the
1953 <a href="#propdef-font-family" title="font-family!!property">‘<code
1954 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1955 class=property>fantasy</code></a>’). It follows that the keyword <span
1956 title="normal value">‘<code class=property>normal</code>’</span>
1957 applies to the two remaining properties: <a href="#propdef-font-style"
1958 title="font-style!!property">‘<code
1959 class=property>font-style</code>’</a> and <a
1960 href="#propdef-font-weight" title="font-weight!!property">‘<code
1961 class=property>font-weight</code>’</a>.
1963 <p>The sixth rule sets the <a href="#propdef-font-style"
1964 title="font-style!!property">‘<code
1965 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1966 title="font-stretch!!property">‘<code
1967 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1968 href="#propdef-font-size"><code
1969 class=property>font-size</code></a>’</span>, and <a
1970 href="#propdef-font-family" title="font-family!!property">‘<code
1971 class=property>font-family</code>’</a>, the other font properties being
1972 set to their initial values.
1973 </div>
1975 <p>Since the <a href="#propdef-font-stretch"
1976 title="font-stretch!!property">‘<code
1977 class=property>font-stretch</code>’</a> property was not defined in CSS
1978 2.1, when using <a href="#propdef-font-stretch"
1979 title="font-stretch!!property">‘<code
1980 class=property>font-stretch</code>’</a> values within ‘<a
1981 href="#propdef-font"><code class=property>font</code></a>’ rules,
1982 authors should include a extra version compatible with older user agents:
1984 <pre>p {
1985 font: 80% sans-serif; /* for older user agents */
1986 font: condensed 80% sans-serif;
1987 }</pre>
1989 <p>The following values refer to system fonts:
1991 <dl>
1992 <dt><strong>caption</strong>
1994 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
1995 etc.).
1997 <dt><strong>icon</strong>
1999 <dd>The font used to label icons.
2001 <dt><strong>menu</strong>
2003 <dd>The font used in menus (e.g., dropdown menus and menu lists).
2005 <dt><strong>message-box</strong>
2007 <dd>The font used in dialog boxes.
2009 <dt><strong>small-caption</strong>
2011 <dd>The font used for labeling small controls.
2013 <dt><strong>status-bar</strong>
2015 <dd>The font used in window status bars.
2016 </dl>
2018 <p>System fonts may only be set as a whole; that is, the font family, size,
2019 weight, style, etc. are all set at the same time. These values may then be
2020 altered individually if desired. If no font with the indicated
2021 characteristics exists on a given platform, the user agent should either
2022 intelligently substitute (e.g., a smaller version of the ‘<code
2023 class=property>caption</code>’ font might be used for the ‘<code
2024 class=property>small-caption</code>’ font), or substitute a user agent
2025 default font. As for regular fonts, if, for a system font, any of the
2026 individual properties are not part of the operating system's available
2027 user preferences, those properties should be set to their initial values.
2029 <p>That is why this property is "almost" a shorthand property: system fonts
2030 can only be specified with this property, not with <a
2031 href="#propdef-font-family" title="font-family!!property">‘<code
2032 class=property>font-family</code>’</a> itself, so <span
2033 class=property>‘<a href="#propdef-font"><code
2034 class=property>font</code></a>’</span> allows authors to do more than
2035 the sum of its subproperties. However, the individual properties such as
2036 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2037 class=property>font-weight</code>’</a> are still given values taken from
2038 the system font, which can be independently varied.
2040 <p>Note that the keywords used for the system fonts listed above are only
2041 treated as keywords when they occur in the initial position, in other
2042 positions the same string is treated as part of the font family name:
2044 <pre> font: menu; /* use the font settings for system menus */
2045 font: large menu; /* use a font family named "menu" */</pre>
2047 <div class=example>
2048 <p style="display:none">Example(s):
2050 <p>
2052 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2053 button p { font: menu }
2054 button p em { font-weight: bolder }
2055 </pre>
2057 <p>If the font used for dropdown menus on a particular system happened to
2058 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2059 that were descendants of BUTTON would be displayed as if this rule were
2060 in effect:
2062 <pre>button p { font: 600 9pt Charcoal }
2063 </pre>
2065 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2066 class=property>font</code></a>’</span> shorthand resets to its initial
2067 value any property not explicitly given a value, this has the same effect
2068 as this declaration:
2070 <pre>button p {
2071 font-style: normal;
2072 font-variant: normal;
2073 font-weight: 600;
2074 font-size: 9pt;
2075 line-height: normal;
2076 font-family: Charcoal
2077 }
2078 </pre>
2079 </div>
2080 <!-- prop: font-synthesis -->
2082 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2083 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2084 property</h3>
2086 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2087 <tbody>
2088 <tr>
2089 <td>Name:
2091 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2093 <tr>
2094 <td>Value:
2096 <td>none | [ weight || style ]
2098 <tr>
2099 <td>Initial:
2101 <td>weight style
2103 <tr>
2104 <td>Applies to:
2106 <td>all elements
2108 <tr>
2109 <td>Inherited:
2111 <td>yes
2113 <tr>
2114 <td>Percentages:
2116 <td>N/A
2118 <tr>
2119 <td>Media:
2121 <td>visual
2123 <tr>
2124 <td>Computed value:
2126 <td>as specified
2128 <tr>
2129 <td>Animatable:
2131 <td>no
2132 </table>
2134 <p>This property controls whether user agents are allowed to synthesize
2135 bold or oblique font faces when a font family lacks bold or italic faces.
2136 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2137 specified, user agents must not synthesize bold faces and if ‘<code
2138 class=property>style</code>’ is not specified user agents must not
2139 synthesize italic faces. A value of ‘<code class=property>none</code>’
2140 disallows all synthetic faces.
2142 <div class=example>
2143 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2145 <pre>*:lang(ar) { font-synthesis: none; }
2146 </pre>
2147 </div>
2149 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2151 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2152 id=at-font-face-rule style="font-weight: inherit; font-style:
2153 inherit"><code>@font-face</code></dfn> rule</h3>
2155 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2156 for linking to fonts that are automatically fetched and activated when
2157 needed. This allows authors to select a font that closely matches the
2158 design goals for a given page rather than limiting the font choice to a
2159 set of fonts available on all platforms. A set of font descriptors define
2160 the location of a font resource, either locally or externally, along with
2161 the style characteristics of an individual face. Multiple <a
2162 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2163 construct font families with a variety of faces. Using CSS font matching
2164 rules, a user agent can selectively download only those faces that are
2165 needed for a given piece of text.
2167 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2168 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2169 at-keyword followed by a block of descriptor declarations. In terms of the
2170 grammar, this specification defines the following productions:
2172 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2173 : <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>*
2174 ;
2176 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2177 : <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>
2178 ;</pre>
2180 <p>The following new definitions are introduced:
2182 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2183 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2185 <p>The following new token is introduced:
2187 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2189 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2190 specifies a value for every font descriptor, either implicitly or
2191 explicitly. Those not given explicit values in the rule take the initial
2192 value listed with each descriptor in this specification. These descriptors
2193 apply solely within the context of the <a
2194 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2195 are defined, and do not apply to document language elements. There is no
2196 notion of which elements the descriptors apply to or whether the values
2197 are inherited by child elements. When a given descriptor occurs multiple
2198 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2199 rule, only the last descriptor declaration is used and all prior
2200 declarations for that descriptor are ignored.
2202 <div class=example>
2203 <p>To use a downloadable font called Gentium:</p>
2205 <pre>
2206 @font-face {
2207 font-family: Gentium;
2208 src: url(http://example.com/fonts/Gentium.ttf);
2209 }
2211 p { font-family: Gentium, serif; }
2212 </pre>
2214 <p>The user agent will download Gentium and use it when rendering text
2215 within paragraph elements. If for some reason the site serving the font
2216 is unavailable, the default serif font will be used.</p>
2217 </div>
2219 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2220 rules define a set of fonts available for use within the documents that
2221 contain these rules. When font matching is done, fonts defined using these
2222 rules are considered before other available fonts on a system.
2224 <p>Downloaded fonts are only available to documents that reference them.
2225 The process of activating these fonts must not make them available to
2226 other applications or to documents that don't directly link to the same
2227 font. User agent implementers might consider it convenient to use
2228 downloaded fonts when rendering characters in other documents for which no
2229 other available font exists as part of the <a
2230 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2231 However, this would cause a security leak since the contents of one page
2232 would be able to affect other pages, something an attacker could use as an
2233 attack vector. These restrictions do not affect caching behavior, fonts
2234 are cached the same way other web resources are cached.
2236 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2237 properties in a declaration block, declarations of any descriptors that
2238 are not supported by the user agent must be ignored. <a
2239 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2240 font-family and src descriptor; if either of these are missing, the <a
2241 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2242 must be ignored entirely.
2244 <p>In cases where user agents have limited platform resources or implement
2245 the ability to disable downloadable font resources, <a
2246 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2247 ignored; the behavior of individual descriptors as defined in this
2248 specification should not be altered.
2250 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2251 href="#descdef-font-family">font-family</a> descriptor</h3>
2253 <table class=descdef>
2254 <tbody>
2255 <tr>
2256 <td>Name:
2258 <td><dfn id=descdef-font-family
2259 title="font-family!!descriptor">font-family</dfn>
2261 <tr>
2262 <td>Value:
2264 <td><a href="#family-name-value"><var><family-name></var></a>
2266 <tr>
2267 <td><em>Initial:</em>
2269 <td>N/A
2270 </table>
2272 <p>This descriptor defines the font family name that will be used in all
2273 CSS font family name matching. It is required for the <a
2274 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2275 overrides the font family names contained in the underlying font data. If
2276 the font family name is the same as a font family available in a given
2277 user's environment, it effectively hides the underlying font for documents
2278 that use the stylesheet. This permits a web author to freely choose
2279 font-family names without worrying about conflicts with font family names
2280 present in a given user's environment. Likewise, platform substitutions
2281 for a given font family name must not be used.
2283 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2284 href="#descdef-src">src</a> descriptor</h3>
2286 <table class=descdef>
2287 <tbody>
2288 <tr>
2289 <td>Name:
2291 <td><dfn id=descdef-src>src</dfn>
2293 <tr>
2294 <td>Value:
2296 <td>[ <url> [format(<string> #)]? | <a
2297 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2299 <tr>
2300 <td><em>Initial:</em>
2302 <td>N/A
2303 </table>
2305 <p>This descriptor specifies the resource containing font data. It is
2306 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2307 rule to be valid. Its value is a prioritized, comma-separated list of
2308 external references or locally-installed font face names. When a font is
2309 needed the user agent iterates over the set of references listed, using
2310 the first one it can successfully activate. Fonts containing invalid data
2311 or local font faces that are not found are ignored and the user agent
2312 loads the next font in the list.
2314 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2315 resolved relative to the location of the style sheet containing the <a
2316 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2317 SVG fonts, the URL points to an element within a document containing SVG
2318 font definitions. If the element reference is omitted, a reference to the
2319 first defined font is implied. Similarly, font container formats that can
2320 contain more than one font must load one and only one of the fonts for a
2321 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2322 Fragment identifiers are used to indicate which font to load. If a
2323 container format lacks a defined fragment identifier scheme,
2324 implementations should use a simple 1-based indexing scheme (e.g.
2325 "font-collection#1" for the first font, "font-collection#2" for the second
2326 font).
2328 <pre>
2329 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2330 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2331 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2332 </pre>
2334 <p>External references consist of a URL, followed by an optional hint
2335 describing the format of the font resource referenced by that URL. The
2336 format hint contains a comma-separated list of format strings that denote
2337 well-known font formats. Conformant user agents must skip downloading a
2338 font resource if the format hints indicate only unsupported or unknown
2339 font formats. If no format hints are supplied, the user agent should
2340 download the font resource.
2342 <pre>
2343 /* load WOFF font if possible, otherwise use OpenType font */
2344 @font-face {
2345 font-family: bodytext;
2346 src: url(ideal-sans-serif.woff) format("woff"),
2347 url(basic-sans-serif.ttf) format("opentype");
2348 }
2349 </pre>
2351 <p>Format strings defined by this specification:
2353 <table class=data id=fontformats>
2354 <thead>
2355 <tr>
2356 <th>String
2358 <th>Font Format
2360 <th>Common extensions
2362 <tbody>
2363 <tr>
2364 <th>"woff"
2366 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2368 <td>.woff
2370 <tr>
2371 <th>"truetype"
2373 <td><a
2374 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2376 <td>.ttf
2378 <tr>
2379 <th>"opentype"
2381 <td><a
2382 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2384 <td>.ttf, .otf
2386 <tr>
2387 <th>"embedded-opentype"
2389 <td><a
2390 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2391 OpenType</a>
2393 <td>.eot
2395 <tr>
2396 <th>"svg"
2398 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2400 <td>.svg, .svgz
2401 </table>
2403 <p>Given the overlap in common usage between TrueType and OpenType, the
2404 format hints "truetype" and "opentype" must be considered as synonymous; a
2405 format hint of "opentype" does not imply that the font contains Postscript
2406 CFF style glyph data or that it contains OpenType layout information (see
2407 <a href="#platform-props-to-css">Appendix A</a> for more background on
2408 this).
2410 <p>When authors would prefer to use a locally available copy of a given
2411 font and download it if it's not, <code>local()</code> can be used. The
2412 locally-installed <dfn
2413 id=font-face-name-value><var><font-face-name></var></dfn> argument
2414 to <code>local()</code> is a format-specific string that uniquely
2415 identifies a single font face within a larger family. The syntax for a <a
2416 href="#font-face-name-value"><var><font-face-name></var></a> is a
2417 unique font face name enclosed by "local(" and ")". The name can
2418 optionally be enclosed in quotes. If unquoted, the unquoted font family
2419 name processing conventions apply; the name must be a sequence of
2420 identifiers separated by whitespace which is converted to a string by
2421 joining the identifiers together separated by a single space.
2423 <pre>
2424 /* regular face of Gentium */
2425 @font-face {
2426 font-family: MyGentium;
2427 src: local(Gentium), /* use locally available Gentium */
2428 url(Gentium.ttf); /* otherwise, download it */
2429 }
2430 </pre>
2432 <p>For OpenType and TrueType fonts, this string is used to match only the
2433 Postscript name or the full font name in the name table of locally
2434 available fonts. Which type of name is used varies by platform and font,
2435 so authors should include both of these names to assure proper matching
2436 across platforms. Platform substitutions for a given font name must not be
2437 used.
2439 <pre>
2440 /* bold face of Gentium */
2441 @font-face {
2442 font-family: MyGentium;
2443 src: local(Gentium Bold), /* full font name */
2444 local(Gentium-Bold), /* Postscript name */
2445 url(GentiumBold.ttf); /* otherwise, download it */
2446 font-weight: bold;
2447 }
2448 </pre>
2450 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2451 specifies the characteristics of a single font within a family, the unique
2452 name used with <code>local()</code> specifies a single font, not an entire
2453 font family. Defined in terms of OpenType font data, the Postscript name
2454 is found in the font's <a
2455 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2456 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2457 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2458 Postscript name is the commonly used key for all fonts on OSX and for
2459 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2460 used as a unique key for fonts with TrueType glyphs on Windows.
2462 <p>For OpenType fonts with multiple localizations of the full font name,
2463 the US English version is used (language ID = 0x409 for Windows and
2464 language ID = 0 for Macintosh) or the first localization when a US English
2465 full font name is not available (the OpenType specification recommends
2466 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2467 fonts minimally include US English names</a>). User agents that also match
2468 other full font names, e.g. matching the Dutch name when the current
2469 system locale is set to Dutch, are considered non-conformant. This is done
2470 not to prefer English but to avoid matching inconsistencies across font
2471 versions and OS localizations, since font style names (e.g. "Bold") are
2472 frequently localized into many languages and the set of localizations
2473 available varies widely across platform and font version. User agents that
2474 match a concatenation of family name (nameID = 1) with style name (nameID
2475 = 2) are considered non-conformant.
2477 <p>This also allows for referencing faces that belong to larger families
2478 that cannot otherwise be referenced.
2480 <div class=example>
2481 <p>Use a local font or reference an SVG font in another document:</p>
2483 <pre>
2484 @font-face {
2485 font-family: Headline;
2486 src: local(Futura-Medium),
2487 url(fonts.svg#MyGeometricModern) format("svg");
2488 }
2489 </pre>
2491 <p>Create an alias for local Japanese fonts on different platforms:</p>
2493 <pre>
2494 @font-face {
2495 font-family: jpgothic;
2496 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2497 }
2498 </pre>
2500 <p>Reference a font face that cannot be matched within a larger family:</p>
2502 <pre>
2503 @font-face {
2504 font-family: Hoefler Text Ornaments;
2505 /* has the same font properties as Hoefler Text Regular */
2506 src: local(HoeflerText-Ornaments);
2507 }
2508 </pre>
2510 <p>Since localized fullnames never match, a document with the header style
2511 rules below would always render using the default serif font, regardless
2512 whether a particular system locale parameter is set to Finnish or not:</p>
2514 <pre>
2515 @font-face {
2516 font-family: SectionHeader;
2517 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2518 font-weight: bold;
2519 }
2521 h2 { font-family: SectionHeader, serif; }
2522 </pre>
2524 <p>A conformant user agent would never load the font ‘<code
2525 class=css>gentium.eot</code>’ in the example below, since it is
2526 included in the first definition of the ‘<a href="#descdef-src"><code
2527 class=property>src</code></a>’ descriptor which is overridden by the
2528 second definition in the same <a
2529 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2531 <pre>
2532 @font-face {
2533 font-family: MainText;
2534 src: url(gentium.eot); /* for use with older non-conformant user agents */
2535 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2536 }
2537 </pre>
2538 </div>
2540 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2541 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2542 href="#descdef-font-weight">font-weight</a>, <a
2543 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2545 <table class=descdef>
2546 <tbody>
2547 <tr>
2548 <td>Name:
2550 <td><dfn id=descdef-font-style
2551 title="font-style!!descriptor">font-style</dfn>
2553 <tr>
2554 <td>Value:
2556 <td>normal | italic | oblique
2558 <tr>
2559 <td><em>Initial:</em>
2561 <td>normal
2562 </table>
2564 <table class=descdef>
2565 <tbody>
2566 <tr>
2567 <td>Name:
2569 <td><dfn id=descdef-font-weight
2570 title="font-weight!!descriptor">font-weight</dfn>
2572 <tr>
2573 <td>Value:
2575 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2577 <tr>
2578 <td><em>Initial:</em>
2580 <td>normal
2581 </table>
2583 <table class=descdef>
2584 <tbody>
2585 <tr>
2586 <td>Name:
2588 <td><dfn id=descdef-font-stretch
2589 title="font-stretch!!descriptor">font-stretch</dfn>
2591 <tr>
2592 <td>Value:
2594 <td>normal | ultra-condensed | extra-condensed | condensed |
2595 semi-condensed | semi-expanded | expanded | extra-expanded |
2596 ultra-expanded
2598 <tr>
2599 <td><em>Initial:</em>
2601 <td>normal
2602 </table>
2604 <p>These descriptors define the characteristics of a font face and are used
2605 in the process of matching styles to specific faces. For a font family
2606 defined with several <a
2607 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2608 can either download all faces in the family or use these descriptors to
2609 selectively download font faces that match actual styles used in document.
2610 The values for these descriptors are the same as those for the
2611 corresponding font properties except that relative keywords are not
2612 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2613 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2614 these descriptors are omitted, initial values are assumed.
2616 <p>The value for these font face style attributes is used in place of the
2617 style implied by the underlying font data. This allows authors to combine
2618 faces in flexible combinations, even in situations where the original font
2619 data was arranged differently. User agents that implement synthetic
2620 bolding and obliquing must only apply synthetic styling in cases where the
2621 font descriptors imply this is needed, rather than based on the style
2622 attributes implied by the font data.
2624 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2625 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2627 <table class=descdef>
2628 <tbody>
2629 <tr>
2630 <td>Name:
2632 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2634 <tr>
2635 <td>Value:
2637 <td><a href="#urange-value"><var><urange></var></a> #
2639 <tr>
2640 <td><em>Initial:</em>
2642 <td>U+0-10FFFF
2643 </table>
2645 <p>This descriptor defines the set of Unicode codepoints that may be
2646 supported by the font face for which it is declared. The descriptor value
2647 is a comma-delimited list of Unicode range (<a
2648 href="#urange-value"><var><urange></var></a>) values. The union of
2649 these ranges defines the set of codepoints that serves as a hint for user
2650 agents when deciding whether or not to download a font resource for a
2651 given text run.
2653 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2654 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2655 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2656 "U+" or "u+" prefix followed by a codepoint range in one of the three
2657 forms listed below. Ranges that do not fit one of the these forms are
2658 invalid and cause the declaration to be ignored.
2660 <dl>
2661 <dt>single codepoint (e.g. U+416)
2663 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2664 digits
2666 <dt>interval range (e.g. U+400-4ff)
2668 <dd>represented as two hyphen-separated valid Unicode codepoints
2669 indicating the inclusive start and end codepoints of a range
2671 <dt>wildcard range (e.g. U+4??)
2673 <dd>defined by the set of codepoints implied when trailing ‘<code
2674 class=css>?</code>’ characters signify any hexadeximal digit
2675 </dl>
2677 <p>Individual codepoints are written using hexadecimal values that
2678 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2679 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2680 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2681 interval ranges, the start and end codepoints are valid Unicode values and
2682 the end codepoint is greater than or equal to the start codepoint.
2684 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2685 "U+???") are valid and equivalent to a wildcard range with an initial zero
2686 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2687 the range of valid Unicode codepoints are invalid. Because of this, the
2688 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2689 characters is five, even though the <a
2690 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2691 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2693 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2694 href="#descdef-unicode-range"><code
2695 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2696 may overlap. The union of these ranges defines the set of codepoints for
2697 which the corresponding font may be used. User agents must not download or
2698 use the font for codepoints outside this set. User agents may normalize
2699 the list of ranges into a list that is different but represents the same
2700 set of codepoints.
2702 <p>The associated font might not contain glyphs for the entire set of
2703 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2704 class=property>unicode-range</code></a>’ descriptor. When the font is
2705 used, the <dfn id=effective-character-map>effective character map</dfn> is
2706 the intersection of the codepoints defined by ‘<a
2707 href="#descdef-unicode-range"><code
2708 class=property>unicode-range</code></a>’ with the font's <a
2709 href="#character-map"><em>character map</em></a>. This allows authors to
2710 define supported ranges in terms of broad ranges without worrying about
2711 the precise codepoint ranges supported by the underlying font.
2713 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2714 to define composite fonts</h3>
2716 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2717 with different unicode ranges for the same family and style descriptor
2718 values can be used to create composite fonts that mix the glyphs from
2719 different fonts for different scripts. This can be used to combine fonts
2720 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2721 or it can be used by authors as a way of segmenting a font into fonts for
2722 commonly used characters and less frequently used characters. Since the
2723 user agent will only pull down the fonts it needs this helps reduce page
2724 bandwidth.
2726 <p>If the unicode ranges overlap for a set of <a
2727 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2728 family and style descriptor values, the rules are ordered in the reverse
2729 order they were defined; the last rule defined is the first to be checked
2730 for a given character.
2732 <p>Example ranges for specific languages or characters:
2734 <dl>
2735 <dt>unicode-range: U+A5;
2737 <dd>a single code point, the yen/yuan symbol
2739 <dt>unicode-range: U+0-7F;
2741 <dd>code range for basic ASCII characters
2743 <dt>unicode-range: U+590-5ff;
2745 <dd>code range for Hebrew characters
2747 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2749 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2750 yen/yuan symbol
2751 </dl>
2753 <div class=example>
2754 <p>The BBC provides news services in a wide variety of languages, many
2755 that are not well supported across all platforms. Using an <a
2756 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2757 provide a font for any of these languages, as it already does via a
2758 manual font download.</p>
2760 <pre>
2761 @font-face {
2762 font-family: BBCBengali;
2763 src: url(fonts/BBCBengali.ttf) format("opentype");
2764 unicode-range: U+00-FF, U+980-9FF;
2765 }
2766 </pre>
2767 </div>
2769 <div class=example>
2770 <p>Technical documents often require a wide range of symbols. The STIX
2771 Fonts project is one project aimed at providing fonts to support a wide
2772 range of technical typesetting in a standardized way. The example below
2773 shows the use of a font that provides glyphs for many of the mathematical
2774 and technical symbol ranges within Unicode:</p>
2776 <pre>
2777 @font-face {
2778 font-family: STIXGeneral;
2779 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2780 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2781 }
2782 </pre>
2783 </div>
2785 <div class=example>
2786 <p>This example shows how an author can override the glyphs used for Latin
2787 characters in a Japanese font with glyphs from a different font. The
2788 first rule specifies no range so it defaults to the entire range. The
2789 range specified in the second rule overlaps but takes precedence because
2790 it is defined later.</p>
2792 <pre>
2793 @font-face {
2794 font-family: JapaneseWithGentium;
2795 src: local(MSMincho);
2796 /* no range specified, defaults to entire range */
2797 }
2799 @font-face {
2800 font-family: JapaneseWithGentium;
2801 src: url(../fonts/Gentium.ttf);
2802 unicode-range: U+0-2FF;
2803 }
2804 </pre>
2805 </div>
2807 <div class=example>
2808 <p>Consider a family constructed to optimize bandwidth by separating out
2809 Latin, Japanese and other characters into different font files:</p>
2811 <pre>
2812 /* fallback font - size: 4.5MB */
2813 @font-face {
2814 font-family: DroidSans;
2815 src: url(DroidSansFallback.ttf);
2816 /* no range specified, defaults to entire range */
2817 }
2819 /* Japanese glyphs - size: 1.2MB */
2820 @font-face {
2821 font-family: DroidSans;
2822 src: url(DroidSansJapanese.ttf);
2823 unicode-range: U+3000-9FFF, U+ff??;
2824 }
2826 /* Latin, Greek, Cyrillic along with some
2827 punctuation and symbols - size: 190KB */
2828 @font-face {
2829 font-family: DroidSans;
2830 src: url(DroidSans.ttf);
2831 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2832 }
2833 </pre>
2835 <p>For simple Latin text, only the font for Latin characters is
2836 downloaded:</p>
2838 <pre>
2839 body { font-family: DroidSans; }
2841 <p>This is that</p>
2842 </pre>
2844 <p>In this case the user agent first checks the unicode-range for the font
2845 containing Latin characters (DroidSans.ttf). Since all the characters
2846 above are in the range U+0-5FF, the user agent downloads the font and
2847 renders the text with that font.</p>
2849 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2851 <pre>
2852 <p>This &#x21e8; that<p>
2853 </pre>
2855 <p>The user agent again first checks the unicode-range of the font
2856 containing Latin characters. Since U+2000-2300 includes the arrow code
2857 point (U+21E8), the user agent downloads the font. For this character
2858 however the Latin font does not have a matching glyph, so the effective
2859 unicode-range used for font matching excludes this code point. Next, the
2860 user agent evaluates the Japanese font. The unicode-range for the
2861 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2862 user agent does not download the Japanese font. Next the fallback font is
2863 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2864 rule for the fallback font does not define unicode-range so its value
2865 defaults to the range of all Unicode code points. The fallback font is
2866 downloaded and used to render the arrow character.</p>
2867 </div>
2869 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2870 href="#descdef-font-variant">font-variant</a> and <a
2871 href="#descdef-font-feature-settings">font-feature-settings</a>
2872 descriptors</h3>
2874 <table class=descdef>
2875 <tbody>
2876 <tr>
2877 <td>Name:
2879 <td><dfn id=descdef-font-variant
2880 title="font-variant!!descriptor">font-variant</dfn>
2882 <tr>
2883 <td>Value:
2885 <td><a href="#font-variant-normal-value"
2886 title="normal!!font-variant">normal</a> | <a
2887 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2888 <a href="#common-lig-values"><var><common-lig-values></var></a>
2889 || <a
2890 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2891 || <a
2892 href="#historical-lig-values"><var><historical-lig-values></var></a>
2893 || <a
2894 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2895 || <a href="#stylistic"><var
2896 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2897 href="#historical-forms"><var>historical-forms</var></a> || <a
2898 href="#styleset"><var
2899 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2900 href="#character-variant"><var
2901 title=character-variant>character-variant(<feature-value-name>
2902 #)</var></a> || <a href="#swash"><var
2903 title=swash>swash(<feature-value-name>)</var></a> || <a
2904 href="#ornaments"><var
2905 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2906 href="#annotation"><var
2907 title=annotation>annotation(<feature-value-name>)</var></a> || [
2908 <a href="#small-caps"><i>small-caps</i></a> | <a
2909 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2910 href="#petite-caps"><i>petite-caps</i></a> | <a
2911 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2912 href="#unicase"><i>unicase</i></a> | <a
2913 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2914 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2915 || <a
2916 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2917 || <a
2918 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2919 || <a href="#ordinal"><i>ordinal</i></a> || <a
2920 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2921 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2922 || <a
2923 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2924 || <a href="#ruby"><i>ruby</i></a> ]
2926 <tr>
2927 <td><em>Initial:</em>
2929 <td>normal
2930 </table>
2932 <table class=descdef>
2933 <tbody>
2934 <tr>
2935 <td>Name:
2937 <td><dfn id=descdef-font-feature-settings
2938 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2940 <tr>
2941 <td>Value:
2943 <td><a href="#font-feature-settings-normal-value"
2944 title="normal!!font-feature-settings">normal</a> | <a
2945 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2947 <tr>
2948 <td><em>Initial:</em>
2950 <td>normal
2951 </table>
2953 <p>These descriptors define initial settings that apply when the font
2954 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2955 rule is rendered. They do not affect font selection. Values are identical
2956 to those defined for the corresponding <a href="#propdef-font-variant"
2957 title="font-variant!!property">‘<code
2958 class=property>font-variant</code>’</a> and <a
2959 href="#propdef-font-feature-settings"
2960 title="font-feature-settings!!property">‘<code
2961 class=property>font-feature-settings</code>’</a> properties defined
2962 below except that the value ‘<code class=property>inherit</code>’ is
2963 omitted. When multiple font feature descriptors or properties are used,
2964 the cumulative effect on text rendering is detailed in the section <a
2965 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2966 cases where specific values define synthesized fallback for certain <a
2967 href="#propdef-font-variant" title="font-variant!!property">‘<code
2968 class=property>font-variant</code>’</a> subproperties, the same
2969 synthesized fallback applies when used within those values are used with
2970 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2971 class=property>font-variant</code>’</a> descriptor.
2973 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2974 guidelines</h3>
2976 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
2977 designed to allow lazy loading of font resources that are only downloaded
2978 when used within a document. A stylesheet can include <a
2979 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
2980 of fonts of which only a select set are used; user agents must only
2981 download those fonts that are referred to within the style rules
2982 applicable to a given page. User agents that download all fonts defined in
2983 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
2984 considering whether those fonts are in fact used within a page are
2985 considered non-conformant. In cases where a font might be downloaded in
2986 character fallback cases, user agents may download a font if it's
2987 contained within the computed value of <a href="#propdef-font-family"
2988 title="font-family!!property">‘<code
2989 class=property>font-family</code>’</a> for a given text run.
2991 <pre>
2992 @font-face {
2993 font-family: GeometricModern;
2994 src: url(font.ttf);
2995 }
2997 p {
2998 /* font will be downloaded for pages with p elements */
2999 font-family: GeometricModern, sans-serif;
3000 }
3002 h2 {
3003 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
3004 font-family: Futura, GeometricModern, sans-serif;
3005 }
3006 </pre>
3008 <p>In cases where textual content is loaded before downloadable fonts are
3009 available, user agents may render text as it would be rendered if
3010 downloadable font resources are not available or they may render text
3011 transparently with fallback fonts to avoid a flash of text using a
3012 fallback font. In cases where the font download fails user agents must
3013 display text, simply leaving transparent text is considered non-conformant
3014 behavior. Authors are advised to use fallback fonts in their font lists
3015 that closely match the vertical metrics of the downloadable fonts to avoid
3016 large page reflows where possible.
3018 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
3019 restriction for fonts</h3>
3021 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
3022 </span>Default same-origin restriction</h4>
3023 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3024 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3025 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3026 -->
3028 <p>User agents must implement a same-origin restriction when loading fonts
3029 via the <a href="#at-font-face-rule"><code>@font-face</code></a>
3030 mechanism. This restriction limits the loading of fonts for a given
3031 document to fonts loaded from the same origin. Fonts can only be loaded
3032 via the same host, port, and method combination as the containing
3033 document, using the <a
3034 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
3035 algorithm</a> described in the <a href="#HTML5"
3036 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
3037 the stylesheet containing <a
3038 href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
3039 when deciding whether a font is same origin or not, only the origin of the
3040 containing document is used. The restriction applies to all font types.
3042 <p>Given a document located at http://example.com/page.html, fonts defined
3043 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
3044 definitions considered cross origin must not be loaded:
3046 <pre>
3047 /* same origin (i.e. domain, protocol, port match document) */
3048 src: url(fonts/simple.ttf);
3049 src: url(//fonts/simple.ttf);
3051 /* cross origin, different protocol */
3052 src: url(https://example.com/fonts/simple.ttf);
3054 /* cross origin, different domain */
3055 src: url(http://another.example.com/fonts/simple.ttf);
3056 </pre>
3058 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
3059 </span>Allowing cross-origin font loading</h4>
3061 <p>User agents must also implement the ability to relax this restriction
3062 using cross-site origin controls <a href="#CORS"
3063 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
3064 Sites can explicitly allow cross-site downloading of font data using the
3065 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
3066 no explicit relaxation mechanism is defined or required.
3068 <p>For font loads over HTTP, cross-origin requests must be made with the
3069 following parameter settings which are used in conjunction with the <a
3070 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
3071 request algorithm</em></a> <a href="#CORS"
3072 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
3074 <ul>
3075 <li><em>request URL</em> — the URL of the font resource in the <a
3076 href="#descdef-src"><code>src</code></a> descriptor
3078 <li><em>request method</em> — GET
3080 <li><em>author request headers</em> — none
3082 <li><em>request entity body</em> — empty
3084 <li><em>source origin</em> — the origin of the page which linked to the
3085 stylesheet
3087 <li><em>manual redirect flag</em> — false
3089 <li><em>omit credentials flag</em> — true
3091 <li><em>force preflight flag</em> — false
3092 </ul>
3094 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3095 Algorithm</h2>
3097 <p>The algorithm below describes how fonts are associated with individual
3098 runs of text. For each character in the run a font family is chosen and a
3099 particular font face is selected containing a glyph for that character.
3101 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3102 font family names</h3>
3104 <p>As part of the font matching algorithm outlined below, user agents must
3105 match font family names used in style rules with actual font family names
3106 contained in fonts available in a given environment or with font family
3107 names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
3108 rules. User agents must match these names case insensitively, using the
3109 "Default Caseless Matching" algorithm outlined in the Unicode
3110 specification <a href="#UNICODE6"
3111 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
3112 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3113 the algorithm must be applied without normalizing the strings involved and
3114 without applying any language-specific tailorings. The case folding method
3115 specified by this algorithm uses the case mappings with status field
3116 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3117 in the CaseFolding.txt file of the Unicode Character Database.
3119 <p class=note> For authors this means that font family names are matched
3120 case insensitively, whether those names exist in a platform font or in the
3121 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3122 in a stylesheet. Authors should take care to ensure that names use a
3123 character sequence consistent with the actual font family name,
3124 particularly when using combining characters such as diacritical marks.
3125 For example, a family name that contains an uppercase A (U+0041) followed
3126 by a combining ring (U+030A) will <strong>not</strong> match a name that
3127 looks identical but which uses the precomposed lowercase a-ring character
3128 (U+00E5) instead of the combining sequence.
3130 <p class=note> Implementors should take care to verify that a given
3131 caseless string comparison implementation uses this precise algorithm and
3132 not assume that a given platform string matching routine follows it, as
3133 many of these have locale-specific behavior or use some level of string
3134 normalization.
3136 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3137 styles</h3>
3139 <p>The procedure for choosing a font for a given character in a run of text
3140 consists of iterating over the font families named by the <a
3141 href="#propdef-font-family" title="font-family!!property">‘<code
3142 class=property>font-family</code>’</a> property, selecting a font face
3143 with the appropriate style based on other font properties and then
3144 determining whether a glyph exists for the given character. This is done
3145 using the <dfn id=character-map>character map</dfn> of the font, data
3146 which maps characters to the default glyph for that character. Codepoint
3147 sequences consisting of a base character followed by a sequence of
3148 combining characters are treated slightly differently, see the section on
3149 <a href="#cluster-matching">cluster matching</a> below.
3151 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3152 given font family is defined to be the face that would be selected if all
3153 font style properties were set to their initial value.
3155 <ol id=fontmatchingalg>
3156 <li>Using the computed font property values for a given element, the user
3157 agent starts with the first family name specified by the <a
3158 href="#propdef-font-family" title="font-family!!property">‘<code
3159 class=property>font-family</code>’</a> property.
3161 <li>If the family name is a generic family keyword, the user agent looks
3162 up the appropriate font family name to be used. User agents may choose
3163 the generic font family to use based on the language of the containing
3164 element or the Unicode range of the character.
3166 <li>For other family names, the user agent attempts to find the family
3167 name among fonts defined via <a
3168 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3169 among available system fonts, matching names with a <a
3170 href="#font-family-casing">case-insensitive comparison</a> as outlined in
3171 the section above. On systems containing fonts with multiple localized
3172 font family names, user agents must match any of these names independent
3173 of the underlying system locale or platform API used. If the font
3174 resources defined for a given face in an <a
3175 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3176 available or contain invalid font data, then the face should be treated
3177 as not present in the family. If no faces are present for a family
3178 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3179 rules, the family should be treated as missing; matching a platform font
3180 with the same name must not occur in this case.
3182 <li>If a font family match occurs, the user agent assembles the set of
3183 font faces in that family and then narrows the set to a single face using
3184 other font properties in the order given below. A group of faces defined
3185 via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
3186 identical font descriptor values but differing ‘<a
3187 href="#descdef-unicode-range"><code
3188 class=property>unicode-range</code></a>’ values are considered to be a
3189 single <dfn id=composite-face>composite face</dfn> for this step:
3190 <ol id=fontstylematchingalg>
3191 <li><a href="#propdef-font-stretch"
3192 title="font-stretch!!property">‘<code
3193 class=property>font-stretch</code>’</a> is tried first. If the
3194 matching set contains faces with width values matching the <a
3195 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3196 class=property>font-stretch</code>’</a> value, faces with other width
3197 values are removed from the matching set. If there is no face that
3198 exactly matches the width value the nearest width is used instead. If
3199 the value of <a href="#propdef-font-stretch"
3200 title="font-stretch!!property">‘<code
3201 class=property>font-stretch</code>’</a> is <a
3202 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3203 class=property>normal</code>’</a> or one of the condensed values,
3204 narrower width values are checked first, then wider values. If the
3205 value of <a href="#propdef-font-stretch"
3206 title="font-stretch!!property">‘<code
3207 class=property>font-stretch</code>’</a> is one of the expanded
3208 values, wider values are checked first, followed by narrower values.
3209 Once the closest matching width has been determined by this process,
3210 faces with other widths are removed from the matching set.
3212 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3213 class=property>font-style</code>’</a> is tried next. If the value of
3214 <a href="#propdef-font-style" title="font-style!!property">‘<code
3215 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3216 class=property>italic</code></a>’, italic faces are checked first,
3217 then oblique, then normal faces. If the value is ‘<a
3218 href="#oblique"><code class=property>oblique</code></a>’, oblique
3219 faces are checked first, then italic faces and then normal faces. If
3220 the value is <a href="#font-style-normal-value"
3221 title="normal!!font-style">‘<code
3222 class=property>normal</code>’</a>, normal faces are checked first,
3223 then oblique faces, then italic faces. Faces with other style values
3224 are excluded from the matching set. User agents are permitted to
3225 distinguish between italic and oblique faces within platform font
3226 families but this is not required, so all italic or oblique faces may
3227 be treated as italic faces. However, within font families defined via
3228 <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
3229 and oblique faces must be distinguished using the value of the <a
3230 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3231 class=property>font-style</code>’</a> descriptor. For families that
3232 lack any italic or oblique faces, users agents may create artificial
3233 oblique faces, if this is permitted by the value of the ‘<a
3234 href="#propdef-font-synthesis"><code
3235 class=property>font-synthesis</code></a>’ property.
3237 <li><a href="#propdef-font-weight"
3238 title="font-weight!!property">‘<code
3239 class=property>font-weight</code>’</a> is matched next, so it will
3240 always reduce the matching set to a single font face. If bolder/lighter
3241 relative weights are used, the effective weight is calculated based on
3242 the inherited weight value, as described in the definition of the <a
3243 href="#propdef-font-weight" title="font-weight!!property">‘<code
3244 class=property>font-weight</code>’</a> property. Given the desired
3245 weight and the weights of faces in the matching set after the steps
3246 above, if the desired weight is available that face matches. Otherwise,
3247 a weight is chosen using the rules below:
3248 <ul>
3249 <li>If the desired weight is less than 400, weights below the desired
3250 weight are checked in descending order followed by weights above the
3251 desired weight in ascending order until a match is found.
3253 <li>If the desired weight is greater than 500, weights above the
3254 desired weight are checked in ascending order followed by weights
3255 below the desired weight in descending order until a match is found.
3257 <li>If the desired weight is 400, 500 is checked first and then the
3258 rule for desired weights less than 400 is used.
3260 <li>If the desired weight is 500, 400 is checked first and then the
3261 rule for desired weights less than 400 is used.
3262 </ul>
3264 <li><span class=property>‘<a href="#propdef-font-size"><code
3265 class=property>font-size</code></a>’</span> must be matched within a
3266 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3267 are rounded to the nearest whole pixel, while the tolerance for
3268 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3269 by ‘<code class=property>em</code>’ values in other properties, are
3270 based on the <span class=property>‘<a href="#propdef-font-size"><code
3271 class=property>font-size</code></a>’</span> value that is used, not
3272 the one that is specified.
3273 </ol>
3275 <li>
3276 <p>If the matched face is defined via <a
3277 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
3278 must use the procedure below to select a single font:
3280 <ol>
3281 <li>If the font resource has not been loaded and the range of characters
3282 defined by the ‘<a href="#descdef-unicode-range"><code
3283 class=property>unicode-range</code></a>’ descriptor value includes
3284 the character in question, load the font.
3286 <li>After downloading, if the <a
3287 href="#effective-character-map"><em>effective character map</em></a>
3288 supports the character in question, select that font.
3289 </ol>
3291 <p>When the matched face is a <a href="#composite-face"><em>composite
3292 face</em></a>, user agents must use the procedure above on each of the
3293 faces in the <a href="#composite-face"><em>composite face</em></a> in
3294 reverse order of <a
3295 href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
3297 <p>While the download occurs, user agents may either wait until the font
3298 is downloaded or render once with substituted font metrics and render
3299 again once the font is downloaded.</p>
3301 <li>
3302 <p>If no matching face exists or the matched face does not contain a
3303 glyph for the character to be rendered, the next family name is selected
3304 and the previous three steps repeated. Glyphs from other faces in the
3305 family are not considered. The only exception is that user agents may
3306 optionally substitute a synthetically obliqued version of the <a
3307 href="#default-face"><em>default face</em></a> if that face supports a
3308 given glyph and synthesis of these faces is permitted by the value of
3309 the ‘<a href="#propdef-font-synthesis"><code
3310 class=property>font-synthesis</code></a>’ property. For example, a
3311 synthetic italic version of the regular face may be used if the italic
3312 face doesn't support glyphs for Arabic.</p>
3313 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3316 <li>If there are no more font families to be evaluated and no matching
3317 face has been found, then the user agent performs a <dfn
3318 id=system-font-fallback>system font fallback</dfn> procedure to find the
3319 best match for the character to be rendered. The result of this procedure
3320 may vary across user agents.
3322 <li>If a particular character cannot be displayed using any font, the user
3323 agent should indicate by some means that a character is not being
3324 displayed, displaying either a symbolic representation of the missing
3325 glyph (e.g. using a <a
3326 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3327 Font</a>) or using the missing character glyph from a default font.
3328 </ol>
3330 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3332 <p>When text contains characters such as combining diacritics, ideally the
3333 base character should be rendered using the same font as the diacritic,
3334 this assures proper placement of the diacritic. For this reason, the font
3335 matching algorithm for clusters is more specialized than the general case
3336 of matching a single character by itself. For sequences containing
3337 variation selectors, which indicate the precise glyph to be used for a
3338 given character, user agents always attempt <a
3339 href="#system-font-fallback"><em>system font fallback</em></a> to find the
3340 appropriate glyph before using the default glyph of the base character.
3342 <p>A font is considered to <em>support</em> a given character if (1) the
3343 character is contained in the font's <a
3344 href="#character-map"><em>character map</em></a> and (2) if required by
3345 the containing script, shaping information is available for that
3346 character. Some legacy fonts may include a given character in the <a
3347 href="#character-map"><em>character map</em></a> but lack the shaping
3348 information (e.g. <a
3349 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3350 layout tables</a> or <a
3351 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3352 tables</a>) necessary for correctly rendering text runs containing that
3353 character.
3355 <p>A sequence of codepoints containing combining diacritics or other
3356 modifiers is 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 supports that character, select this font
3371 for the sequence.
3372 </ol>
3374 <li>If no font was found in the font list in step 1:
3375 <ol>
3376 <li>If <em>c1</em> is a variation selector, system fallback must be used
3377 to find a font that supports the full sequence of <em>b + c1</em>. If
3378 no font on the system supports the full sequence, match the single
3379 character <em>b</em> using the normal procedure for matching single
3380 characters and ignore the variation selector. Note: a sequence with
3381 more than one variation selector is treated as an encoding error and
3382 the trailing selectors are ignored.
3384 <li>Otherwise, the user agent may optionally use system font fallback to
3385 match a font that supports the entire cluster.
3386 </ol>
3388 <li>If no font is found in step 2, use the matching sequence from step 1
3389 to determine the longest sequence that is completely matched by a font in
3390 the font list and attempt to match the remaining combining characters
3391 separately using the rules for single characters.
3392 </ol>
3394 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3395 issues</h3>
3397 <p>The procedure above is always performed on text runs containing Unicode
3398 characters, documents using legacy encodings are assumed to have been
3399 transcoded before matching fonts. For fonts containing <a
3400 href="#character-map"><em title="character map">character maps</em></a>
3401 for both legacy encodings and Unicode, the contents of the legacy encoding
3402 <a href="#character-map"><em>character map</em></a> must have no effect on
3403 the results of the font matching process.
3405 <p>The font matching process does not assume that text runs are in either
3406 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3407 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3408 details). Layout engines often convert base character plus combining
3409 character sequences into precomposed characters if they exist. The font
3410 matching algorithm outlined here supports both ways and fonts can
3411 generally support either but variations can occur. Authors should always
3412 tailor their choice of fonts to their content, including whether that
3413 content contains normalized or denormalized character streams.
3415 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3416 the fonts in the fontlist contain a glyph for that codepoint, user agents
3417 must display some form of missing glyph symbol for that character rather
3418 than attempting <a href="#system-font-fallback"><em>system font
3419 fallback</em></a> for that codepoint. When matching the replacement
3420 character U+FFFD, user agents may skip the font matching process and
3421 immediately display some form of missing glyph symbol, they are not
3422 required to display the glyph from the font that would be selected by the
3423 font matching process.
3425 <p>In general, the fonts for a given family will all have the same or
3426 similar <a href="#character-map"><em title="character map">character
3427 maps</em></a>. The process outlined here is designed to handle even font
3428 families containing faces with widely variant <a href="#character-map"><em
3429 title="character map">character maps</em></a>. However, authors are
3430 cautioned that the use of such families can lead to unexpected results.
3432 <p>Optimizations of this process are allowed provided that an
3433 implementation behaves as if the algorithm had been followed exactly.
3434 Matching occurs in a well-defined order to insure that the results are as
3435 consistent as possible across user agents, given an identical set of
3436 available fonts and rendering technology.
3438 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3439 changes since CSS 2.1</h3>
3441 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3442 These changes were made to better reflect actual font matching behavior
3443 across user agent implementations.
3445 <p>Differences compared to the font matching algorithm in CSS 2.1:
3447 <ul>
3448 <li>The algorithm includes font-stretch matching.
3450 <li>All possible font-style matching scenarios are delineated.
3452 <li>Small-caps fonts are not matched as part of the font matching process,
3453 they are now handled via font features.
3455 <li>Unicode variation selector matching is required.
3457 <li>Cluster sequences are matched as a unit.
3458 </ul>
3460 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3461 examples</h3>
3463 <div class=example>
3464 <p>It's useful to note that the CSS selector syntax may be used to create
3465 language-sensitive typography. For example, some Chinese and Japanese
3466 characters are unified to have the same Unicode code point, although the
3467 abstract glyphs are not the same in the two languages.
3469 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3470 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3471 </pre>
3473 <p>This selects any element that has the given language - Japanese or
3474 Traditional Chinese - and uses the appropriate font.
3475 </div>
3477 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3479 <p>Modern font technologies support a variety of advanced typographic and
3480 language-specific font features. Using these features, a single font can
3481 provide glyphs for a wide range of ligatures, contextual and stylistic
3482 alternates, tabular and old-style figures, small capitals, automatic
3483 fractions, swashes, and alternates specific to a given language. To allow
3484 authors control over these font capabilities, the ‘<code
3485 class=property>font-variant</code>’ property has been expanded for CSS3.
3486 It now functions as a shorthand for a set of properties that provide
3487 control over stylistic font features.
3489 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3490 selection and positioning</h3>
3492 <p>Simple fonts used for displaying Latin text use a very basic processing
3493 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3494 which maps each character to a glyph for that character. Glyphs for
3495 subsequent characters are simply placed one after the other along a run of
3496 text. Modern font formats such as OpenType and AAT (Apple Advanced
3497 Typography) use a richer processing model. The glyph for a given character
3498 can be chosen and positioned not just based on the codepoint of the
3499 character itself, but also on adjacent characters as well as the language,
3500 script, and features enabled for the text. Font features may be required
3501 for specific scripts, or recommended as enabled by default or they might
3502 be stylistic features meant to be used under author control.
3504 <p>For a good visual overview of these features, see the <a
3505 href="#OPENTYPE-FONT-GUIDE"
3506 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3507 For a detailed description of glyph processing for OpenType fonts, see <a
3508 href="#WINDOWS-GLYPH-PROC"
3509 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3511 <p>Stylistic font features can be classified into two broad categories:
3512 ones that affect the harmonization of glyph shapes with the surrounding
3513 context, such as kerning and ligature features, and ones such as the
3514 small-caps, subscript/superscript and alternate features that affect shape
3515 selection.
3517 <p>The subproperties of <a href="#propdef-font-variant"
3518 title="font-variant!!property">‘<code
3519 class=property>font-variant</code>’</a> listed below are used to control
3520 these stylistic font features. They do not control features that are
3521 required for displaying certain scripts, such as the OpenType features
3522 used when displaying Arabic or Indic language text. They affect glyph
3523 selection and positioning, but do not affect font selection as described
3524 in the font matching section (except in cases required for compatibility
3525 with CSS 2.1).
3527 <p>To assure consistent behavior across user agents, the equivalent
3528 OpenType property settings are listed for individual properties and are
3529 normative. When using other font formats these should be used as a
3530 guideline to map CSS font feature property values to specific font
3531 features.
3533 <h3 id=language-specific-support><span class=secno>6.2
3534 </span>Language-specific display</h3>
3536 <p>OpenType also supports language-specific glyph selection and
3537 positioning, so that text can be displayed correctly in cases where the
3538 language dictates a specific display behavior. Many languages share a
3539 common script, but the shape of certain letters can vary across those
3540 languages. For example, certain Cyrillic letters have different shapes in
3541 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3542 with an explicit fi-ligature that lacks a dot on the "i". However, in
3543 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3544 important to not use this ligature or use a specialized version that
3545 contains a dot over the "i". The example below shows language-specific
3546 variations based on stylistic traditions found in Spanish, Italian and
3547 French orthography:
3549 <div class=featex><img alt="language specific forms, spanish"
3550 src=locl-1.png></div>
3552 <div class=featex><img alt="language specific forms, italian"
3553 src=locl-2.png></div>
3555 <div class=featex><img alt="language specific forms, french"
3556 src=locl-3.png></div>
3558 <p>If the content language of the element is known according to the rules
3559 of the <a
3560 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3561 language</a>, user agents are required to infer the OpenType language
3562 system from the content language and use that when selecting and
3563 positioning glyphs using an OpenType font.
3565 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3566 declare the OpenType language to be used, for example when displaying text
3567 in a given language that uses the typographic conventions of another
3568 language or when the font does not explicitly support a given language but
3569 supports a language that shares common typographic conventions. The ‘<a
3570 href="#propdef-font-language-override"><code
3571 class=property>font-language-override</code></a>’ property is used for
3572 this purpose.</p>
3573 <!-- prop: font-kerning -->
3575 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3576 href="#propdef-font-kerning">font-kerning</a> property</h3>
3578 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3579 <tbody>
3580 <tr>
3581 <td>Name:
3583 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3585 <tr>
3586 <td>Value:
3588 <td><a href="#font-kerning-auto-value"
3589 title="auto!!font-kerning">auto</a> | <a
3590 href="#font-kerning-normal-value"
3591 title="normal!!font-kerning">normal</a> | <a
3592 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3594 <tr>
3595 <td>Initial:
3597 <td>auto
3599 <tr>
3600 <td>Applies to:
3602 <td>all elements
3604 <tr>
3605 <td>Inherited:
3607 <td>yes
3609 <tr>
3610 <td>Percentages:
3612 <td>N/A
3614 <tr>
3615 <td>Media:
3617 <td>visual
3619 <tr>
3620 <td>Computed value:
3622 <td>as specified
3624 <tr>
3625 <td>Animatable:
3627 <td>no
3628 </table>
3630 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3631 property controls metric kerning, kerning that utilizes adjustment data
3632 contained in the font.
3634 <dl>
3635 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3637 <dd>Specifies that kerning is applied at the discretion of the user agent
3639 <dt><dfn id=font-kerning-normal-value
3640 title="normal!!font-kerning">normal</dfn>
3642 <dd>Specifies that kerning is applied
3644 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3646 <dd>Specifies that kerning is not applied
3647 </dl>
3649 <p>For fonts that do not include kerning data this property will have no
3650 visible effect. When rendering with OpenType fonts, the <a
3651 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3652 specification suggests that kerning be enabled by default. When kerning is
3653 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3654 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3655 instead). User agents must also support fonts that only support kerning
3656 via data contained in a <span class=tag>kern</span> font table, as
3657 detailed in the OpenType specification. If the ‘<code
3658 class=property>letter-spacing</code>’ property is defined, kerning
3659 adjustments are considered part of the default spacing and letter spacing
3660 adjustments are made after kerning has been applied.
3662 <p>When set to ‘<code class=property>auto</code>’, user agents can
3663 determine whether to apply kerning or not based on a number of factors:
3664 text size, script, or other factors that influence text processing speed.
3665 Authors who want proper kerning should use <a
3666 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3667 class=property>normal</code>’</a> to explicitly enable kerning.
3668 Likewise, some authors may prefer to disable kerning in situations where
3669 performance is more important than precise appearance. However, in
3670 well-designed modern implementations the use of kerning generally does not
3671 have a large impact on text rendering speed.</p>
3672 <!-- prop: font-variant-ligatures -->
3674 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3675 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3676 property</h3>
3678 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3679 <tbody>
3680 <tr>
3681 <td>Name:
3683 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3685 <tr>
3686 <td>Value:
3688 <td><a href="#font-variant-ligatures-normal-value"
3689 title="normal!!font-variant-ligatures">normal</a> | <a
3690 href="#font-variant-ligatures-none-value"
3691 title="none!!font-variant-ligatures">none</a> | [ <a
3692 href="#common-lig-values"><var><common-lig-values></var></a> ||
3693 <a
3694 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3695 || <a
3696 href="#historical-lig-values"><var><historical-lig-values></var></a>
3697 || <a
3698 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3699 ]
3701 <tr>
3702 <td>Initial:
3704 <td>normal
3706 <tr>
3707 <td>Applies to:
3709 <td>all elements
3711 <tr>
3712 <td>Inherited:
3714 <td>yes
3716 <tr>
3717 <td>Percentages:
3719 <td>N/A
3721 <tr>
3722 <td>Media:
3724 <td>visual
3726 <tr>
3727 <td>Computed value:
3729 <td>as specified
3731 <tr>
3732 <td>Animatable:
3734 <td>no
3735 </table>
3737 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3738 more harmonized forms.
3740 <pre
3741 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>
3743 <pre
3744 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>
3746 <pre
3747 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>
3749 <pre
3750 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>
3752 <p>Individual values have the following meanings:
3754 <dl>
3755 <dt><dfn id=font-variant-ligatures-normal-value
3756 title="normal!!font-variant-ligatures">normal</dfn>
3758 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3759 title="normal!!font-variant-ligatures">‘<code
3760 class=property>normal</code>’</a> specifies that common default
3761 features are enabled, <a href="#font-feature-resolution">as described in
3762 detail in the next section</a>. For OpenType fonts, common ligatures and
3763 contextual forms are on by default, discretionary and historical
3764 ligatures are not.
3766 <dt><dfn id=font-variant-ligatures-none-value
3767 title="none!!font-variant-ligatures">none</dfn>
3769 <dd>Specifies that all types of ligatures and contextual forms covered by
3770 this property are explicitly disabled. In situations where ligatures are
3771 not considered necessary, this may improve the speed of text rendering.
3773 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3775 <dd>Enables display of common ligatures (OpenType features: <span
3776 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3777 enabled by default.
3778 </dl>
3780 <div class=featex><img alt="common ligature example" src=liga.png></div>
3782 <dl>
3783 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3785 <dd>Disables display of common ligatures (OpenType features: <span
3786 class=tag>liga, clig</span>).
3788 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3790 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3791 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3792 decided by the type designer, so authors will need to refer to the
3793 documentation of a given font to understand which ligatures are
3794 considered discretionary.
3795 </dl>
3797 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3799 <dl>
3800 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3802 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3803 class=tag>dlig</span>).
3805 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3807 <dd>Enables display of historical ligatures (OpenType feature: <span
3808 class=tag>hlig</span>).
3809 </dl>
3811 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3813 <dl>
3814 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3816 <dd>Disables display of historical ligatures (OpenType feature: <span
3817 class=tag>hlig</span>).
3819 <dt><dfn id=contextual>contextual</dfn>
3821 <dd>Enables display of contextual alternates (OpenType feature: <span
3822 class=tag>calt</span>). Although not strictly a ligature feature, like
3823 ligatures this feature is commonly used to harmonize the shapes of glyphs
3824 with the surrounding context. For OpenType fonts, this feature is on by
3825 default.
3826 </dl>
3828 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3830 <dl>
3831 <dt><dfn id=no-contextual>no-contextual</dfn>
3833 <dd>Disables display of contextual alternates (OpenType feature: <span
3834 class=tag>calt</span>).
3835 </dl>
3837 <p>Required ligatures, needed for correctly rendering complex scripts, are
3838 not affected by the settings above, including ‘<code
3839 class=property>none</code>’ (OpenType feature: <span
3840 class=tag>rlig</span>).</p>
3841 <!-- prop: font-variant-position -->
3843 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3844 and superscript forms: the <a
3845 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3847 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3848 <tbody>
3849 <tr>
3850 <td>Name:
3852 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3854 <tr>
3855 <td>Value:
3857 <td><a href="#font-variant-position-normal-value"
3858 title="normal!!font-variant-position">normal</a> | <a
3859 href="#sub">sub</a> | <a href="#super">super</a>
3861 <tr>
3862 <td>Initial:
3864 <td>normal
3866 <tr>
3867 <td>Applies to:
3869 <td>all elements
3871 <tr>
3872 <td>Inherited:
3874 <td>yes
3876 <tr>
3877 <td>Percentages:
3879 <td>N/A
3881 <tr>
3882 <td>Media:
3884 <td>visual
3886 <tr>
3887 <td>Computed value:
3889 <td>as specified
3891 <tr>
3892 <td>Animatable:
3894 <td>no
3895 </table>
3897 <p>This property is used to enable typographic subscript and superscript
3898 glyphs. These are alternate glyphs designed within the same em-box as
3899 default glyphs and are intended to be laid out on the same baseline as the
3900 default glyphs, with no resizing or repositioning of the baseline. They
3901 are explicitly designed to match the surrounding text and to be more
3902 readable without affecting the line height.
3904 <div class=figure><img alt="comparison between real subscript glyphs and
3905 synthesized ones" src=realsubscripts.png>
3906 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3907 (bottom)
3908 </div>
3910 <p>Individual values have the following meanings:
3912 <dl>
3913 <dt><dfn id=font-variant-position-normal-value
3914 title="normal!!font-variant-position">normal</dfn>
3916 <dd>None of the features listed below are enabled.
3918 <dt><dfn id=sub>sub</dfn>
3920 <dd>Enables display of subscript variants (OpenType feature: <span
3921 class=tag>subs</span>).
3923 <dt><dfn id=super>super</dfn>
3925 <dd>Enables display of superscript variants (OpenType feature: <span
3926 class=tag>sups</span>).
3927 </dl>
3929 <p>Because of the semantic nature of subscripts and superscripts, when the
3930 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3931 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3932 given contiguous run of text, if a variant glyph is not available for all
3933 the characters in the run, simulated glyphs must be synthesized for all
3934 characters using reduced forms of the glyphs that would be used without
3935 this feature applied. This is done per run to avoid a mixture of variant
3936 glyphs and synthesized ones that would not align correctly. In the case of
3937 OpenType fonts that lack subscript or superscript glyphs for a given
3938 character, user agents must use the appropriate subscript and superscript
3939 metrics specified in the selected font's <a
3940 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3941 table</a> <a href="#OPENTYPE"
3942 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3943 and offset of the synthesized substitutes.
3945 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3946 using superscript metrics" src=superscript-alt-synth.png>
3947 <p class=caption>Superscript alternate glyph (left), synthesized
3948 superscript glyphs (middle), and incorrect mixture of the two (right)
3949 </div>
3951 <p>In situations where text decorations are only applied to runs of text
3952 containing superscript or subscript glyphs, the synthesized glyphs must be
3953 used to avoid problems with the placement of decorations.
3955 <p>In the past, user agents have used font-size and vertical-align to
3956 simulate subscripts and superscripts for the <code title="HTML sub
3957 element">sub</code> and <code title="HTML sup element">sup</code>
3958 elements. To allow a backwards compatible way of defining subscripts and
3959 superscripts, it is recommended that authors use conditional rules <a
3960 href="#CSS3-CONDITIONAL"
3961 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3962 older user agents will still render subscripts and superscripts via the
3963 older mechanism.
3965 <p>Authors should note that fonts typically only provide subscript and
3966 superscript glyphs for a subset of all characters supported by the font.
3967 For example, while subscript and superscript glyphs are often available
3968 for Latin numbers, glyphs for punctuation and letter characters are less
3969 frequently provided. The synthetic fallback rules defined for this
3970 property assure that subscripts and superscripts will always appear but
3971 the appearance may not match author expectations if the font used does not
3972 provide the appropriate alternate glyph for all characters contained in a
3973 subscript or superscript.
3975 <p>This property is not cumulative. Applying it to elements within a
3976 subscript or superscript won't nest the placement of a subscript or
3977 superscript glyph. Images contained within text runs where the value of
3978 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3979 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3980 drawn just as they would if the value was <a
3981 href="#font-variant-position-normal-value"
3982 title="normal!!font-variant-position">‘<code
3983 class=property>normal</code>’</a>.</p>
3984 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
3985 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
3987 <p>Because of these limitations, ‘<a
3988 href="#propdef-font-variant-position"><code
3989 class=property>font-variant-position</code></a>’ is not recommended for
3990 use in user agent stylesheets. Authors should use it in cases where
3991 subscripts or superscripts will only contain the narrow range of
3992 characters supported by the fonts specified.
3994 <p class=note>The variant glyphs use the same baseline as the default
3995 glyphs would use. There is no shift in the placement along the baseline,
3996 so the use of variant glyphs doesn't affect the height of the inline box
3997 or alter the height of the linebox. This makes superscript and subscript
3998 variants ideal for situations where it's important that leading remain
3999 constant, such as in multi-column layout.
4001 <div class=example>
4002 <p>A typical user agent default style for the <a class=tag
4003 href="#sub">sub</a> element:</p>
4005 <pre>sub {
4006 vertical-align: sub;
4007 font-size: smaller;
4008 line-height: normal;
4009 }
4010 </pre>
4012 <p>Using font-variant-position to specify typographic subscripts in a way
4013 that will still show subscripts in older user agents:</p>
4015 <pre>@supports ( font-variant-position: sub ) {
4017 sub {
4018 vertical-align: baseline;
4019 font-size: 100%;
4020 line-height: inherit;
4021 font-variant-position: sub;
4022 }
4024 }
4025 </pre>
4027 <p>User agents that support the ‘<a
4028 href="#propdef-font-variant-position"><code
4029 class=property>font-variant-position</code></a>’ property will select a
4030 subscript variant glyph and render this without adjusting the baseline or
4031 font-size. Older user agents will ignore the ‘<a
4032 href="#propdef-font-variant-position"><code
4033 class=property>font-variant-position</code></a>’ property definition
4034 and use the standard defaults for subscripts.</p>
4035 </div>
4036 <!-- prop: font-variant-caps -->
4038 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4039 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4041 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4042 <tbody>
4043 <tr>
4044 <td>Name:
4046 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4048 <tr>
4049 <td>Value:
4051 <td><a href="#font-variant-caps-normal-value"
4052 title="normal!!font-variant-caps">normal</a> | <a
4053 href="#small-caps">small-caps</a> | <a
4054 href="#all-small-caps">all-small-caps</a> | <a
4055 href="#petite-caps">petite-caps</a> | <a
4056 href="#all-petite-caps">all-petite-caps</a> | <a
4057 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4059 <tr>
4060 <td>Initial:
4062 <td>normal
4064 <tr>
4065 <td>Applies to:
4067 <td>all elements
4069 <tr>
4070 <td>Inherited:
4072 <td>yes
4074 <tr>
4075 <td>Percentages:
4077 <td>N/A
4079 <tr>
4080 <td>Media:
4082 <td>visual
4084 <tr>
4085 <td>Computed value:
4087 <td>as specified
4089 <tr>
4090 <td>Animatable:
4092 <td>no
4093 </table>
4095 <p>This property allows the selection of alternate glyphs used for small or
4096 petite capitals or for titling. These glyphs are specifically designed to
4097 blend well with the surrounding normal glyphs, to maintain the weight and
4098 readability which suffers when text is simply resized to fit this purpose.
4100 <p>Individual values have the following meanings:
4102 <dl>
4103 <dt><dfn id=font-variant-caps-normal-value
4104 title="normal!!font-variant-caps">normal</dfn>
4106 <dd>None of the features listed below are enabled.
4108 <dt><dfn id=small-caps>small-caps</dfn>
4110 <dd>Enables display of small capitals (OpenType feature: <span
4111 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4112 uppercase letters but are reduced to the size of lowercase letters.
4113 </dl>
4115 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4117 <dl>
4118 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4120 <dd>Enables display of small capitals for both upper and lowercase letters
4121 (OpenType features: <span class=tag>c2sc, smcp</span>).
4123 <dt><dfn id=petite-caps>petite-caps</dfn>
4125 <dd>Enables display of petite capitals (OpenType feature: <span
4126 class=tag>pcap</span>).
4128 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4130 <dd>Enables display of petite capitals for both upper and lowercase
4131 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4133 <dt><dfn id=unicase>unicase</dfn>
4135 <dd>Enables display of mixture of small capitals for uppercase letters
4136 with normal lowercase letters (OpenType feature: <span
4137 class=tag>unic</span>).
4139 <dt><dfn id=titling-caps>titling-caps</dfn>
4141 <dd>Enables display of titling capitals (OpenType feature: <span
4142 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4143 use with lowercase letters. When used in all uppercase titling sequences
4144 they can appear too strong. Titling capitals are designed specifically
4145 for this situation.
4146 </dl>
4148 <p>The availability of these glyphs is based on whether a given feature is
4149 defined or not in the feature list of the font. User agents can optionally
4150 decide this on a per-script basis but should explicitly not decide this on
4151 a per-character basis.
4153 <p>Some fonts may only support a subset or none of the features described
4154 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4155 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4156 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4157 is specified but small-caps glyphs are not available for a given font,
4158 user agents should simulate a small-caps font, for example by taking a
4159 normal font and replacing the glyphs for lowercase letters with scaled
4160 versions of the glyphs for uppercase characters (replacing the glyphs for
4161 both upper and lowercase letters in the case of ‘<a
4162 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4164 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4165 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4166 width=512px>
4167 <p class=caption>Synthetic vs. real small-caps
4168 </div>
4170 <p>To match the surrounding text, a font may provide alternate glyphs for
4171 caseless characters when these features are enabled but when a user agent
4172 simulates small capitals, it must not attempt to simulate alternates for
4173 codepoints which are considered caseless.
4175 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4176 characters with small-caps, all-small-caps enabled" class=hires
4177 src=small-capitals-variations.png width=418px>
4178 <p class=caption>Caseless characters with small-caps, all-small-caps
4179 enabled
4180 </div>
4182 <p>If either ‘<a href="#petite-caps"><code
4183 class=property>petite-caps</code></a>’ or ‘<a
4184 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4185 is specified for a font that doesn't support these features, the property
4186 behaves as if ‘<a href="#small-caps"><code
4187 class=property>small-caps</code></a>’ or ‘<a
4188 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4189 respectively, had been specified. If ‘<a href="#unicase"><code
4190 class=property>unicase</code></a>’ is specified for a font that doesn't
4191 support that feature, the property behaves as if ‘<a
4192 href="#small-caps"><code class=property>small-caps</code></a>’ was
4193 applied only to lowercased uppercase letters. If ‘<a
4194 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4195 specified with a font that does not support this feature, this property
4196 has no visible effect. When simulated small capital glyphs are used, for
4197 scripts that lack uppercase and lowercase letters, ‘<a
4198 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4199 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4200 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4201 ‘<a href="#all-petite-caps"><code
4202 class=property>all-petite-caps</code></a>’ and ‘<a
4203 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4204 effect.
4206 <p>When casing transforms are used to simulate small capitals, the casing
4207 transformations must match those used for the <span
4208 class=property>‘<code class=property>text-transform</code>’</span>
4209 property.
4211 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4212 replace glyphs in a small-caps font so that the text appears in all
4213 uppercase letters.
4215 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4216 all-small-caps in acronym-laden text" class=hires
4217 src=acronym-laden-text.png width=596px>
4218 <p class=caption>Using small capitals to improve readability in
4219 acronym-laden text
4220 </div>
4222 <div class=example>
4223 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4225 <pre>blockquote { font-style: italic; }
4226 blockquote:first-line { font-variant: small-caps; }
4228 <blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none">I'll be honor-bound to slap them like a haddock.</a></blockquote>
4229 </pre>
4230 </div>
4231 <!-- prop: font-variant-numeric -->
4233 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4234 formatting: the <a
4235 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4237 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4238 <tbody>
4239 <tr>
4240 <td>Name:
4242 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4244 <tr>
4245 <td>Value:
4247 <td><a href="#font-variant-numeric-normal-value"
4248 title="normal!!font-variant-numeric">normal</a> | [ <a
4249 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4250 || <a
4251 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4252 || <a
4253 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4254 || <a href="#ordinal">ordinal</a> || <a
4255 href="#slashed-zero">slashed-zero</a> ]
4257 <tr>
4258 <td>Initial:
4260 <td>normal
4262 <tr>
4263 <td>Applies to:
4265 <td>all elements
4267 <tr>
4268 <td>Inherited:
4270 <td>yes
4272 <tr>
4273 <td>Percentages:
4275 <td>N/A
4277 <tr>
4278 <td>Media:
4280 <td>visual
4282 <tr>
4283 <td>Computed value:
4285 <td>as specified
4287 <tr>
4288 <td>Animatable:
4290 <td>no
4291 </table>
4293 <p>Specifies control over numerical forms. The example below shows how some
4294 of these values can be combined to influence the rendering of tabular data
4295 with fonts that support these features. Within normal paragraph text,
4296 proportional numbers are used while tabular numbers are used so that
4297 columns of numbers line up properly:
4299 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4300 number styles" src=numberstyles.png>
4301 <p class=caption>Using number styles
4302 </div>
4304 <p>Possible combinations:
4306 <pre
4307 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>
4309 <pre
4310 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>
4312 <pre
4313 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>
4315 <p>Individual values have the following meanings:
4317 <dl>
4318 <dt><dfn id=font-variant-numeric-normal-value
4319 title="normal!!font-variant-numeric">normal</dfn>
4321 <dd>None of the features listed below are enabled.
4323 <dt><dfn id=lining-nums>lining-nums</dfn>
4325 <dd>Enables display of lining numerals (OpenType feature: <span
4326 class=tag>lnum</span>).
4328 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4330 <dd>Enables display of old-style numerals (OpenType feature: <span
4331 class=tag>onum</span>).
4333 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4335 <dd>Enables display of proportional numerals (OpenType feature: <span
4336 class=tag>pnum</span>).
4338 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4340 <dd>Enables display of tabular numerals (OpenType feature: <span
4341 class=tag>tnum</span>).
4343 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4345 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4346 class=tag>frac</span>).
4347 </dl>
4349 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4351 <dl>
4352 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4354 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4355 class=tag>afrc</span>).
4356 </dl>
4358 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4360 <dl>
4361 <dt><dfn id=ordinal>ordinal</dfn>
4363 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4364 <span class=tag>ordn</span>).
4366 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4368 <dd>Enables display of slashed zeros (OpenType feature: <span
4369 class=tag>zero</span>).
4370 </dl>
4372 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4374 <div class=example id=steak-marinade>
4375 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4376 and old-style numerals:</p>
4378 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4380 <h4>Steak marinade:</h4>
4381 <ul>
4382 <li><span class="amount">2</span> tbsp olive oil</li>
4383 <li><span class="amount">1</span> tbsp lemon juice</li>
4384 <li><span class="amount">1</span> tbsp soy sauce</li>
4385 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4386 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4387 <li>Salt &amp; pepper</li>
4388 </ul>
4390 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4391 for a few hours or overnight.</p>
4392 </pre>
4394 <p>Note that the fraction feature is only applied to values not the entire
4395 paragraph. Fonts often implement this feature using contextual rules
4396 based on the use of the slash (‘<code class=css>/</code>’) character.
4397 As such, it's not suitable for use as a paragraph-level style.</p>
4398 </div>
4399 <!-- prop: font-variant-alternates -->
4401 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4402 and swashes: the <a
4403 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4404 property</h3>
4406 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4407 <tbody>
4408 <tr>
4409 <td>Name:
4411 <td><dfn
4412 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4414 <tr>
4415 <td>Value:
4417 <td>normal | [ <a href="#stylistic"
4418 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4419 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4420 title=styleset>styleset(<feature-value-name> #)</a> || <a
4421 href="#character-variant"
4422 title=character-variant>character-variant(<feature-value-name>
4423 #)</a> || <a href="#swash"
4424 title=swash>swash(<feature-value-name>)</a> || <a
4425 href="#ornaments"
4426 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4427 href="#annotation"
4428 title=annotation>annotation(<feature-value-name>)</a> ]
4430 <tr>
4431 <td>Initial:
4433 <td>normal
4435 <tr>
4436 <td>Applies to:
4438 <td>all elements
4440 <tr>
4441 <td>Inherited:
4443 <td>yes
4445 <tr>
4446 <td>Percentages:
4448 <td>N/A
4450 <tr>
4451 <td>Media:
4453 <td>visual
4455 <tr>
4456 <td>Computed value:
4458 <td>as specified
4460 <tr>
4461 <td>Animatable:
4463 <td>no
4464 </table>
4466 <p>For any given character, fonts can provide a variety of alternate glyphs
4467 in addition to the default glyph for that character. This property
4468 provides control over the selection of these alternate glyphs.
4470 <p>For many of the property values listed below, several different
4471 alternate glyphs are available. How many alternates are available and what
4472 they represent is font-specific, so these are each marked <dfn
4473 id=font-specific>font specific</dfn> in the value definitions below.
4474 Because the nature of these alternates is font-specific, the <a
4475 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4476 rule is used to define values for a specific font family or set of
4477 families that associate a font-specific numeric
4478 <code><feature-index></code> with a custom
4479 <code><feature-value-name></code>, which is then used in this
4480 property to select specific alternates:
4482 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4484 p {
4485 font-family: Noble Script;
4486 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4487 }</pre>
4489 <p>When a particular <code><feature-value-name></code> has not been
4490 defined for a given family or for a particular feature type, the computed
4491 value must be the same as if it had been defined. However, property values
4492 that contain these undefined <code><feature-value-name></code>
4493 identifiers must be ignored when choosing glyphs.
4495 <pre>/* these two style rules are effectively the same */
4496 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4497 p { font-variant-alternates: normal; }
4498 </pre>
4500 <p>This allows values to be defined and used for a given set of font
4501 families but ignored if fallback occurs, since the font family name would
4502 be different. If a given value is outside the range supported by a given
4503 font, the value is ignored. These values never apply to generic font
4504 families.
4506 <p>Individual values have the following meanings:
4508 <dl>
4509 <dt><dfn id=font-variant-alternates-normal-value
4510 title="normal!!font-variant-alternates">normal</dfn>
4512 <dd>None of the features listed below are enabled.
4514 <dt><dfn id=historical-forms>historical-forms</dfn>
4516 <dd>Enables display of historical forms (OpenType feature: <span
4517 class=tag>hist</span>).
4518 </dl>
4520 <div class=featex><img alt="historical form example" src=hist.png></div>
4522 <dl>
4523 <dt><dfn id=stylistic
4524 title=stylistic>stylistic(<feature-value-name>)</dfn>
4526 <dd>Enables display of stylistic alternates (<a
4527 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4528 class=tag>salt <feature-index></span>).
4529 </dl>
4531 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4533 <dl>
4534 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4535 #)</dfn>
4537 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4538 specific</em></a>, OpenType feature: <span
4539 class=tag>ss<feature-index></span> OpenType currently defines <span
4540 class=tag>ss01</span> through <span class=tag>ss20</span>).
4541 </dl>
4543 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4545 <dl>
4546 <dt><dfn id=character-variant
4547 title=character-variant>character-variant(<feature-value-name>
4548 #)</dfn>
4550 <dd>Enables display of specific character variants (<a
4551 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4552 class=tag>cv<feature-index></span> OpenType currently defines <span
4553 class=tag>cv01</span> through <span class=tag>cv99</span>).
4555 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4557 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4558 specific</em></a>, OpenType feature: <span class=tag>swsh
4559 <feature-index>, cswh <feature-index></span>).
4560 </dl>
4562 <div class=featex><img alt="swash example" src=swsh.png></div>
4564 <dl>
4565 <dt><dfn id=ornaments
4566 title=ornaments>ornaments(<feature-value-name>)</dfn>
4568 <dd>Enables replacement of default glyphs with ornaments, if provided in
4569 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4570 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4571 may offer ornament glyphs as alternates for a wide collection of
4572 characters; however, displaying arbitrary characters (e.g.,
4573 alphanumerics) as ornaments is poor practice as it distorts the semantics
4574 of the data. Font designers are encouraged to encode all ornaments
4575 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4576 alternates for the bullet character (U+2022) to allow authors to select
4577 the desired glyph using ‘<a href="#ornaments"><code
4578 class=property>ornaments</code></a>’.
4579 </dl>
4581 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4583 <dl>
4584 <dt><dfn id=annotation
4585 title=annotation>annotation(<feature-value-name>)</dfn>
4587 <dd>Enables display of alternate annotation forms (<a
4588 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4589 class=tag>nalt <feature-index></span>).
4590 </dl>
4592 <div class=featex><img alt="alternate annotation form example"
4593 src=nalt.png></div>
4595 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4596 specific alternates: the <dfn id=at-font-feature-values-rule
4597 style="font-weight: inherit; font-style:
4598 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4600 <p>Several of the possible values of ‘<a
4601 href="#propdef-font-variant-alternates"><code
4602 class=property>font-variant-alternates</code></a>’ listed above are
4603 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4604 features fonts may define not just a single glyph but a set of alternate
4605 glyphs with an index to select a given alternate. Since these are font
4606 family specific, the <a
4607 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4608 rule is used to define named values for these indices for a given family.
4610 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4611 reference section</a> for a description of the interfaces used to modify
4612 these rules via the CSS Object Model.
4614 <div class=example>
4615 <p>In the case of the swash Q in the example shown above, the swash could
4616 be specified using these style rules:</p>
4618 <pre>
4620 @font-feature-values Jupiter Sans {
4621 @swash {
4622 delicate: 1;
4623 flowing: 2;
4624 }
4625 }
4627 h2 { font-family: Jupiter Sans, sans-serif; }
4629 /* show the second swash variant in h2 headings */
4630 h2:first-letter { font-variant-alternates: swash(flowing); }
4632 <h2>Quick</h2></pre>
4634 <p>When Jupiter Sans is present, the second alternate swash alternate will
4635 be displayed. When not present, no swash character will be shown, since
4636 the specific named value "flowing" is only defined for the Jupiter Sans
4637 family. The @-mark indicates the name of the property value for which a
4638 named value can be used. The name "flowing" is chosen by the author. The
4639 index that represents each alternate is defined within a given font's
4640 data.</p>
4641 </div>
4643 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4645 <p>An <a
4646 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4647 rule is composed of a list of font families followed by a block containing
4648 individual <a href="#featurevalueblock"><i
4649 title="feature_value_block">feature value blocks</i></a> that take the
4650 form of @-rules. Each block defines a set of named values for a specific
4651 font feature when a given set of font families is used. Effectively, they
4652 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4653 ⟨values⟩ are the numeric indices used for specific features defined
4654 for a given font.
4656 <p>In terms of the grammar, this specification defines the following
4657 productions:
4659 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4660 : <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>*
4661 '{' <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>*
4662 ;
4664 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4665 : <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> ]*
4666 ;
4668 <dfn id=fontfamilyname>font_family_name</dfn>
4669 : <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> ]* ]
4670 ;
4672 <dfn id=featurevalueblock>feature_value_block</dfn>
4673 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4674 '{' <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>*
4675 ;
4677 <dfn id=featuretype>feature_type</dfn>:
4678 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4679 ;
4681 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4682 : <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> ]*
4683 ;
4684 </pre>
4686 <p>The following new token is introduced:
4688 <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>;}
4689 </pre>
4691 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4692 value blocks</i></a> are handled as <a
4693 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4694 consist of everything up to the next block or semi-colon, whichever comes
4695 first.
4697 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4698 family list</i></a> is a comma-delimited list of <a
4699 href="#fontfamilyname"><i title="font_family_name">font family
4700 names</i></a> that match the definition of <a
4701 href="#family-name-value"><var><family-name></var></a> for the <a
4702 href="#propdef-font-family" title="font-family!!property">‘<code
4703 class=property>font-family</code>’</a> property. This means that only
4704 named font families are allowed, rules that include generic or system
4705 fonts in the list of font families are syntax errors. However, if a user
4706 agent defines a generic font to be a specific named font (e.g. Helvetica),
4707 the settings associated with that family name will be used. If syntax
4708 errors occur within the font family list, the entire rule must be ignored.
4710 <p>Within <a href="#featurevalueblock"><i
4711 title="feature_value_block">feature value blocks</i></a>, the <a
4712 href="#featuretype"><i title="feature_type">feature type</i></a> is
4713 ‘<code class=css>@</code>’ followed by the name of one of the <a
4714 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4715 href="#propdef-font-variant-alternates"><code
4716 class=property>font-variant-alternates</code></a>’ (e.g. <a
4717 href="#swash"><code>@swash</code></a>). The identifiers used within
4718 feature value definitions follow the rules of CSS user identifiers and are
4719 case-sensitive. They are unique only for a given set of font families and
4720 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4721 same identifier used with a different <a href="#featuretype"><i
4722 title="feature_type">feature type</i></a> is treated as a separate and
4723 distinct value. If the same identifier is defined mulitple times for a
4724 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4725 and font family, the last defined value is used. Values associated with a
4726 given identifier are limited to integer values 0 or greater.
4728 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4729 title="feature_value_definition">feature value definition</i></a>, such as
4730 invalid identifiers or values, the entire <a
4731 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4732 value definition</i></a> must be omitted, just as syntax errors in style
4733 declarations are handled. When the <a href="#featuretype"><i
4734 title="feature_type">feature type</i></a> is invalid, the entire
4735 associated <a href="#featurevalueblock"><i
4736 title="feature_value_block">feature value block</i></a> must be ignored.
4738 <div class=example>
4739 <p>Rules that are equivalent given syntax error handling:</p>
4741 <pre>@font-feature-values Bongo {
4742 @swash { ornate: 1; }
4743 annotation { boxed: 4; } /* should be @annotation! */
4744 @swash { double-loops: 1; flowing: -1; } /* negative value */
4745 @ornaments ; /* incomplete definition */
4746 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4747 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4748 }</pre>
4750 <p>The example above is equivalent to:</p>
4752 <pre>@font-feature-values Bongo {
4753 @swash { ornate: 1; }
4754 @swash { double-loops: 1; }
4755 @styleset { double-W: 14; sharp-terminals: 16 1; }
4756 }</pre>
4757 </div>
4759 <p>If multiple <a
4760 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4761 rules are defined for a given family, the resulting values definitions are
4762 the union of the definitions contained within these rules. This allows a
4763 set of named values to be defined for a given font family globally for a
4764 site and specific additions made per-page.
4766 <div class=example>
4767 <p>Using both site-wide and per-page feature values:</p>
4769 <pre>
4770 site.css:
4772 @font-feature-values Mercury Serif {
4773 @styleset {
4774 stacked-g: 3; /* "two-storey" versions of g, a */
4775 stacked-a: 4;
4776 }
4777 }
4779 page.css:
4781 @font-feature-values Mercury Serif {
4782 @styleset {
4783 geometric-m: 7; /* alternate version of m */
4784 }
4785 }
4787 body {
4788 font-family: Mercury Serif, serif;
4790 /* enable both the use of stacked g and alternate m */
4791 font-variant-alternates: styleset(stacked-g, geometric-m);
4792 }</pre>
4793 </div>
4795 <div class=example>
4796 <p>Using a commonly named value allows authors to use a single style rule
4797 to cover a set of fonts for which the underlying selector is different
4798 for each font. If either font in the example below is found, a circled
4799 number glyph will be used:</p>
4801 <pre>@font-feature-values Taisho Gothic {
4802 @annotation { boxed: 1; circled: 4; }
4803 }
4805 @font-feature-values Otaru Kisa {
4806 @annotation { circled: 1; black-boxed: 3; }
4807 }
4809 h3.title {
4810 /* circled form defined for both fonts */
4811 font-family: Taisho Gothic, Otaru Kisa;
4812 font-variant: annotation(circled);
4813 }</pre>
4814 </div>
4816 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4817 </span>Multi-valued feature value definitions</h4>
4819 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4820 href="#propdef-font-variant-alternates"><code
4821 class=property>font-variant-alternates</code></a>’ property values take
4822 a single value (e.g. ‘<a href="#swash"><code
4823 class=property>swash</code></a>’). The ‘<a
4824 href="#character-variant"><code
4825 class=property>character-variant</code></a>’ property value allows two
4826 values and ‘<a href="#styleset"><code
4827 class=property>styleset</code></a>’ allows an unlimited number.
4829 <p>For the styleset property value, multiple values indicate the style sets
4830 to be enabled. Values between 1 and 99 enable OpenType features <span
4831 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4832 OpenType standard only officially defines <span class=tag>ss01</span>
4833 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4834 than 99 or equal to 0 do not generate a syntax error when parsed but
4835 enable no OpenType features.
4837 <pre>@font-feature-values Mars Serif {
4838 @styleset {
4839 alt-g: 1; /* implies ss01 = 1 */
4840 curly-quotes: 3; /* implies ss03 = 1 */
4841 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4842 }
4844 @styleset {
4845 dumb: 125; /* >99, ignored */
4846 }
4848 @swash {
4849 swishy: 3 5; /* more than 1 value for swash, syntax error */
4850 }
4851 }
4853 p.codeblock {
4854 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4855 font-variant-alternates: styleset(curly-quotes, code);
4856 }</pre>
4858 <p>For character-variant, a single value between 1 and 99 indicates the
4859 enabling of OpenType feature <span class=tag>cv01</span> through <span
4860 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4861 to 0 are ignored but do not generate a syntax error when parsed but enable
4862 no OpenType features. When two values are listed, the first value
4863 indicates the feature used and the second the value passed for that
4864 feature. If more than two values are assigned to a given name, a syntax
4865 error occurs and the entire <a href="#featurevaluedefinition"><i
4866 title="feature_value_definition">feature value definition</i></a> is
4867 ignored.
4869 <pre>@font-feature-values MM Greek {
4870 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4871 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4872 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4873 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4874 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4875 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4876 @character-variant { silly: 105; } /* >99, ignored */
4877 @character-variant { dumb: 323 3; } /* >99, ignored */
4878 }
4880 #title {
4881 /* use the third alternate beta, first alternate gamma */
4882 font-variant-alternates: character-variant(beta-3, gamma);
4883 }
4885 p {
4886 /* zeta-2 follows zeta, implies cv20 = 2 */
4887 font-variant-alternates: character-variant(zeta, zeta-2);
4888 }
4890 .special {
4891 /* zeta follows zeta-2, implies cv20 = 3 */
4892 font-variant-alternates: character-variant(zeta-2, zeta);
4893 }</pre>
4895 <div class=figure><img alt="Matching text on Byzantine seals using
4896 character variants" src=byzantineseal.png>
4897 <p class=caption>Byzantine seal text displayed with character variants
4898 </div>
4900 <div class=example>
4901 <p>In the figure above, the text in red is rendered using a font
4902 containing character variants that mimic the character forms found on a
4903 Byzantine seal from the 8th century A.D. Two lines below is the same text
4904 displayed in a font without variants. Note the two variants for U and N
4905 used on the seal.</p>
4907 <pre>@font-feature-values Athena Ruby {
4908 @character-variant {
4909 leo-B: 2 1;
4910 leo-M: 13 3;
4911 leo-alt-N: 14 1;
4912 leo-N: 14 2;
4913 leo-T: 20 1;
4914 leo-U: 21 2;
4915 leo-alt-U: 21 4;
4916 }
4917 }
4919 p {
4920 font-variant: discretionary-ligatures,
4921 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4922 }
4924 span.alt-N {
4925 font-variant-alternates: character-variant(leo-alt-N);
4926 }
4928 span.alt-U {
4929 font-variant-alternates: character-variant(leo-alt-U);
4930 }
4932 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4934 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4935 </pre>
4936 </div>
4938 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4939 Asian text rendering: the <a
4940 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4941 property</h3>
4943 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4944 <tbody>
4945 <tr>
4946 <td>Name:
4948 <td><dfn
4949 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4951 <tr>
4952 <td>Value:
4954 <td><a href="#font-variant-east-asian-normal-value"
4955 title="normal!!font-variant-east-asian">normal</a> | [ <a
4956 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4957 || <a
4958 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4959 || <a href="#ruby">ruby</a> ]
4961 <tr>
4962 <td>Initial:
4964 <td>normal
4966 <tr>
4967 <td>Applies to:
4969 <td>all elements
4971 <tr>
4972 <td>Inherited:
4974 <td>yes
4976 <tr>
4977 <td>Percentages:
4979 <td>N/A
4981 <tr>
4982 <td>Media:
4984 <td>visual
4986 <tr>
4987 <td>Computed value:
4989 <td>as specified
4991 <tr>
4992 <td>Animatable:
4994 <td>no
4995 </table>
4997 <p>Allows control of glyph substitution and sizing in East Asian text.
4999 <pre
5000 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>
5002 <pre
5003 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>
5005 <p>Individual values have the following meanings:
5007 <dl>
5008 <dt><dfn id=font-variant-east-asian-normal-value
5009 title="normal!!font-variant-east-asian">normal</dfn>
5011 <dd>None of the features listed below are enabled.
5013 <dt><dfn id=jis78>jis78</dfn>
5015 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
5016 class=tag>jp78</span>).
5017 </dl>
5019 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
5021 <dl>
5022 <dt><dfn id=jis83>jis83</dfn>
5024 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
5025 class=tag>jp83</span>).
5027 <dt><dfn id=jis90>jis90</dfn>
5029 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
5030 class=tag>jp90</span>).
5032 <dt><dfn id=jis04>jis04</dfn>
5034 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5035 class=tag>jp04</span>).
5036 <p>The various JIS variants reflect the glyph forms defined in different
5037 Japanese national standards. Fonts generally include glyphs defined by
5038 the most recent national standard but it's sometimes necessary to use
5039 older variants, to match signage for example.</p>
5041 <dt><dfn id=simplified>simplified</dfn>
5043 <dd>Enables rendering of simplified forms (OpenType feature: <span
5044 class=tag>smpl</span>).
5046 <dt><dfn id=traditional>traditional</dfn>
5048 <dd>Enables rendering of traditional forms (OpenType feature: <span
5049 class=tag>trad</span>).
5050 </dl>
5052 <p>The ‘<a href="#simplified"><code
5053 class=property>simplified</code></a>’ and ‘<a
5054 href="#traditional"><code class=property>traditional</code></a>’ values
5055 allow control over the glyph forms for characters which have been
5056 simplified over time but for which the older, traditional form is still
5057 used in some contexts. The exact set of characters and glyph forms will
5058 vary to some degree by context for which a given font was designed.
5060 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5062 <dl>
5063 <dt><dfn id=full-width>full-width</dfn>
5065 <dd>Enables rendering of full-width variants (OpenType feature: <span
5066 class=tag>fwid</span>).
5068 <dt><dfn id=proportional-width>proportional-width</dfn>
5070 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5071 <span class=tag>pwid</span>).
5072 </dl>
5074 <div class=featex><img alt="proportionally spaced Japanese example"
5075 src=pwid.png></div>
5077 <dl>
5078 <dt><dfn id=ruby>ruby</dfn>
5080 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5081 class=tag>ruby</span>). Since ruby text is generally smaller than the
5082 associated body text, font designers can design special glyphs for use
5083 with ruby that are more readable than scaled down versions of the default
5084 glyphs. Only glyph selection is affected, there is no associated font
5085 scaling or other change that affects line layout. The red ruby text below
5086 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5087 Note the slight difference in stroke thickness.
5088 </dl>
5090 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5092 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5093 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5094 property</h3>
5096 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5097 <tbody>
5098 <tr>
5099 <td>Name:
5101 <td><dfn id=propdef-font-variant
5102 title="font-variant!!property">font-variant</dfn>
5104 <tr>
5105 <td>Value:
5107 <td><a href="#font-variant-normal-value"
5108 title="normal!!font-variant">normal</a> | <a
5109 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5110 <a href="#common-lig-values"><var><common-lig-values></var></a>
5111 || <a
5112 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5113 || <a
5114 href="#historical-lig-values"><var><historical-lig-values></var></a>
5115 || <a
5116 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5117 || <a href="#stylistic"><var
5118 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5119 href="#historical-forms"><var>historical-forms</var></a> || <a
5120 href="#styleset"><var
5121 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5122 href="#character-variant"><var
5123 title=character-variant>character-variant(<feature-value-name>
5124 #)</var></a> || <a href="#swash"><var
5125 title=swash>swash(<feature-value-name>)</var></a> || <a
5126 href="#ornaments"><var
5127 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5128 href="#annotation"><var
5129 title=annotation>annotation(<feature-value-name>)</var></a> || [
5130 <a href="#small-caps"><i>small-caps</i></a> | <a
5131 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5132 href="#petite-caps"><i>petite-caps</i></a> | <a
5133 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5134 href="#unicase"><i>unicase</i></a> | <a
5135 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5136 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5137 || <a
5138 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5139 || <a
5140 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5141 || <a href="#ordinal"><i>ordinal</i></a> || <a
5142 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5143 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5144 || <a
5145 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5146 || <a href="#ruby"><i>ruby</i></a> ]
5148 <tr>
5149 <td>Initial:
5151 <td>normal
5153 <tr>
5154 <td>Applies to:
5156 <td>all elements
5158 <tr>
5159 <td>Inherited:
5161 <td>yes
5163 <tr>
5164 <td>Percentages:
5166 <td>see individual properties
5168 <tr>
5169 <td>Media:
5171 <td>visual
5173 <tr>
5174 <td>Computed value:
5176 <td>see individual properties
5178 <tr>
5179 <td>Animatable:
5181 <td>see individual properties
5182 </table>
5184 <p>The <a href="#propdef-font-variant"
5185 title="font-variant!!property">‘<code
5186 class=property>font-variant</code>’</a> property is a shorthand for all
5187 font-variant subproperties. The value <dfn id=font-variant-normal-value
5188 title="normal!!font-variant">‘<code
5189 class=property>normal</code>’</dfn> resets all subproperties of <a
5190 href="#propdef-font-variant" title="font-variant!!property">‘<code
5191 class=property>font-variant</code>’</a> to their inital value. The <dfn
5192 id=font-variant-none-value title="none!!font-variant">‘<code
5193 class=property>none</code>’</dfn> value sets ‘<a
5194 href="#propdef-font-variant-ligatures"><code
5195 class=property>font-variant-ligatures</code></a>’ to ‘<code
5196 class=property>none</code>’ and resets all other font feature properties
5197 to their initial value. Like other shorthands, using <a
5198 href="#propdef-font-variant" title="font-variant!!property">‘<code
5199 class=property>font-variant</code>’</a> resets unspecified <a
5200 href="#propdef-font-variant" title="font-variant!!property">‘<code
5201 class=property>font-variant</code>’</a> subproperties to their initial
5202 values. It does not reset the values of either ‘<a
5203 href="#propdef-font-language-override"><code
5204 class=property>font-language-override</code></a>’ or <a
5205 href="#propdef-font-feature-settings"
5206 title="font-feature-settings!!property">‘<code
5207 class=property>font-feature-settings</code>’</a>.
5209 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5210 font feature settings control: the <a
5211 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5213 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5214 <tbody>
5215 <tr>
5216 <td>Name:
5218 <td><dfn id=propdef-font-feature-settings
5219 title="font-feature-settings!!property">font-feature-settings</dfn>
5221 <tr>
5222 <td>Value:
5224 <td><a href="#font-feature-settings-normal-value"
5225 title="normal!!font-feature-settings">normal</a> | <a
5226 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5228 <tr>
5229 <td>Initial:
5231 <td>normal
5233 <tr>
5234 <td>Applies to:
5236 <td>all elements
5238 <tr>
5239 <td>Inherited:
5241 <td>yes
5243 <tr>
5244 <td>Percentages:
5246 <td>N/A
5248 <tr>
5249 <td>Media:
5251 <td>visual
5253 <tr>
5254 <td>Computed value:
5256 <td>as specified
5258 <tr>
5259 <td>Animatable:
5261 <td>no
5262 </table>
5264 <p>This property provides low-level control over OpenType font features. It
5265 is intended as a way of providing access to font features that are not
5266 widely used but are needed for a particular use case.
5268 <p>Authors should generally use <a href="#propdef-font-variant"
5269 title="font-variant!!property">‘<code
5270 class=property>font-variant</code>’</a> and its related subproperties
5271 whenever possible and only use this property for special cases where its
5272 use is the only way of accessing a particular infrequently used font
5273 feature.
5275 <pre>/* enable small caps and use second swash alternate */
5276 font-feature-settings: "smcp", "swsh" 2;</pre>
5278 <p>A value of <dfn id=font-feature-settings-normal-value
5279 title="normal!!font-feature-settings">‘<code
5280 class=property>normal</code>’</dfn> means that no change in glyph
5281 selection or positioning occurs due to this property.
5283 <p>Feature tag values have the following syntax:
5285 <pre
5286 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5288 <p>The <string> is a case-sensitive OpenType feature tag. As
5289 specified in the OpenType specification, feature tags contain four ASCII
5290 characters. Tag strings longer or shorter than four characters, or
5291 containing characters outside the U+20–7E codepoint range are invalid.
5292 Feature tags need only match a feature tag defined in the font, so they
5293 are not limited to explicitly registered OpenType features. Fonts defining
5294 custom feature tags should follow the <a
5295 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5296 rules</a> defined in the OpenType specification <a
5297 href="#OPENTYPE-FEATURES"
5298 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5299 Feature tags not present in the font are ignored; a user agent must not
5300 attempt to synthesize fallback behavior based on these feature tags.
5302 <p>This means that explicitly disabling the <span class=tag>kern</span>
5303 feature will not affect the application of kerning data found in the
5304 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5305 associated with the <span class=tag>kern</span> feature in the ‘<code
5306 class=property>GPOS</code>’ table). Authors should use the ‘<a
5307 href="#propdef-font-kerning"><code
5308 class=property>font-kerning</code></a>’ property to explictly enable or
5309 disable kerning since this property affects both types of kerning.
5311 <p>If present, a value indicates an index used for glyph selection. An
5312 <integer> value must be 0 or greater. A value of 0 indicates that
5313 the feature is disabled. For boolean features, a value of 1 enables the
5314 feature. For non-boolean features, a value of 1 or greater enables the
5315 feature and indicates the feature selection index. A value of ‘<code
5316 class=property>on</code>’ is synonymous with 1 and ‘<code
5317 class=property>off</code>’ is synonymous with 0. If the value is
5318 omitted, a value of 1 is assumed.
5320 <pre>
5321 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5322 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5323 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5324 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5325 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5326 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5327 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5328 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5329 font-feature-settings: dlig; /* invalid, tag must be a string */
5330 </pre>
5332 <p>When values greater than the range supported by the font are specified,
5333 the behavior is explicitly undefined. For boolean features, in general
5334 these will enable the feature. For non-boolean features, out of range
5335 values will in general be equivalent to a 0 value. However, in both cases
5336 the exact behavior will depend upon the way the font is designed
5337 (specifically, which type of lookup is used to define the feature).
5339 <p>Although specifically defined for OpenType feature tags, feature tags
5340 for other modern font formats that support font features may be added in
5341 the future. Where possible, features defined for other font formats should
5342 attempt to follow the pattern of registered OpenType tags.
5344 <div class=example>
5345 <p>The Japanese text below will be rendered with half-width kana
5346 characters:</p>
5348 <pre lang=ja>
5349 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5351 <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>
5352 </pre>
5353 </div>
5355 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5356 language override: the <a
5357 href="#propdef-font-language-override">font-language-override</a> property</h3>
5359 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5360 <tbody>
5361 <tr>
5362 <td>Name:
5364 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5366 <tr>
5367 <td>Value:
5369 <td><a href="#font-language-override-normal-value"
5370 title="normal!!font-language-override">normal</a> | <a
5371 href="#font-language-override-string-value"><var><string></var></a>
5373 <tr>
5374 <td>Initial:
5376 <td><a href="#font-language-override-normal-value"
5377 title="normal!!font-language-override">normal</a>
5379 <tr>
5380 <td>Applies to:
5382 <td>all elements
5384 <tr>
5385 <td>Inherited:
5387 <td>yes
5389 <tr>
5390 <td>Percentages:
5392 <td>N/A
5394 <tr>
5395 <td>Media:
5397 <td>visual
5399 <tr>
5400 <td>Computed value:
5402 <td>as specified
5404 <tr>
5405 <td>Animatable:
5407 <td>no
5408 </table>
5410 <p>Normally, authors can control the use of language-specific glyph
5411 substitutions and positioning by setting the content language of an
5412 element, as <a href="#language-specific-support">described above</a>:
5414 <pre><!-- Display text using S'gaw Karen specific features -->
5415 <p lang="ksw">...</p></pre>
5417 <p>In some cases, authors may need to specify a language system that
5418 differs from the content language, for example due to the need to mimic
5419 another language's typographic traditions. The ‘<a
5420 href="#propdef-font-language-override"><code
5421 class=property>font-language-override</code></a>’ property allows
5422 authors to explicitly specify the language system of the font, overriding
5423 the language system implied by the content language.
5425 <p>Values have the following meanings:
5427 <dl>
5428 <dt><dfn id=font-language-override-normal-value
5429 title="normal!!font-language-override">normal</dfn>
5431 <dd>specifies that when rendering with OpenType fonts, the content
5432 language of the element is used to infer the OpenType language system
5434 <dt><dfn
5435 id=font-language-override-string-value><var><string></var></dfn>
5437 <dd>single three-letter case-sensitive OpenType <a
5438 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5439 system tag</a>, specifies the OpenType language system to be used instead
5440 of the language system implied by the language of the element
5441 </dl>
5442 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5443 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5445 <p>Use of invalid OpenType language system tags must not generate a parse
5446 error but must be ignored when doing glyph selection and placement.
5448 <div class=example>
5449 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5450 Declaration of Human Rights</a> has been translated into a wide variety
5451 of languages. In Turkish, Article 9 of this document might be marked up
5452 as below:</p>
5454 <pre lang=tr><body lang="tr">
5456 <h4>Madde 9</h4>
5457 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5458 </pre>
5460 <p>Here the user agent uses the value of the ‘<code
5461 class=property>lang</code>’ attribute when rendering text and
5462 appropriately renders this text without ‘<code
5463 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5464 href="#propdef-font-language-override"><code
5465 class=property>font-language-override</code></a>’ property.</p>
5467 <p>However, a given font may lack support for a specific language. In this
5468 situation authors may need to use the typographic conventions of a
5469 related language that are supported by that font:</p>
5471 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5473 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5475 <h4>Члeн 9</h4>
5476 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5478 </pre>
5480 <p>The Macedonian text here will be rendered using Serbian typographic
5481 conventions, with the assumption that the font specified supports
5482 Serbian.</p>
5483 </div>
5485 <p><a id=rendering-considerations></a>
5487 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5488 Resolution</h2>
5490 <p>As described in the previous section, font features can be enabled in a
5491 variety of ways, either via the use of <a href="#propdef-font-variant"
5492 title="font-variant!!property">‘<code
5493 class=property>font-variant</code>’</a> or <a
5494 href="#propdef-font-feature-settings"
5495 title="font-feature-settings!!property">‘<code
5496 class=property>font-feature-settings</code>’</a> in a style rule or
5497 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5498 The resolution order for the union of these settings is defined below.
5499 Features defined via CSS properties are applied on top of layout engine
5500 default features.
5502 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5504 <p>For OpenType fonts, user agents must enable the default features defined
5505 in the OpenType documentation for a given script and writing mode.
5506 Required ligatures, common ligatures and contextual forms must be enabled
5507 by default (OpenType features: <span class=tag>rlig, liga, clig,
5508 calt</span>), along with localized forms (OpenType feature: <span
5509 class=tag>locl</span>), and features required for proper display of
5510 composed characters and marks (OpenType features: <span class=tag>ccmp,
5511 mark, mkmk</span>). These features must always be enabled, even when the
5512 value of the <a href="#propdef-font-variant"
5513 title="font-variant!!property">‘<code
5514 class=property>font-variant</code>’</a> and <a
5515 href="#propdef-font-feature-settings"
5516 title="font-feature-settings!!property">‘<code
5517 class=property>font-feature-settings</code>’</a> properties is <span
5518 title="normal value">‘<code class=property>normal</code>’</span>.
5519 Individual features are only disabled when explicitly overridden by the
5520 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5521 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5522 href="#no-common-ligatures"><code
5523 class=property>no-common-ligatures</code></a>’. For handling complex
5524 scripts such as <a
5525 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5526 <a
5527 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5528 or <a
5529 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5530 additional features are required. For upright text within vertical text
5531 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5532 must be enabled.
5534 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5536 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5537 feature property settings are resolved in the order below, in ascending
5538 order of precedence. This ordering is used to construct a combined list of
5539 font features that affect a given text run.
5541 <ol>
5542 <li>Font features enabled by default, including features required for a
5543 given script.
5545 <li>If the font is defined via an <a
5546 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5547 features implied by the font-variant descriptor in the <a
5548 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5550 <li>If the font is defined via an <a
5551 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5552 features implied by the font-feature-settings descriptor in the <a
5553 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5555 <li>Feature settings determined by properties other than <a
5556 href="#propdef-font-variant" title="font-variant!!property">‘<code
5557 class=property>font-variant</code>’</a> or <a
5558 href="#propdef-font-feature-settings"
5559 title="font-feature-settings!!property">‘<code
5560 class=property>font-feature-settings</code>’</a>. For example, setting
5561 a non-default value for the ‘<code
5562 class=property>letter-spacing</code>’ property disables common
5563 ligatures.
5565 <li>Font features implied by the value of the <a
5566 href="#propdef-font-variant" title="font-variant!!property">‘<code
5567 class=property>font-variant</code>’</a> property, the related <a
5568 href="#propdef-font-variant" title="font-variant!!property">‘<code
5569 class=property>font-variant</code>’</a> subproperties and any other CSS
5570 property that uses OpenType features (e.g. the ‘<a
5571 href="#propdef-font-kerning"><code
5572 class=property>font-kerning</code></a>’ property).
5574 <li>Font features implied by the value of <a
5575 href="#propdef-font-feature-settings"
5576 title="font-feature-settings!!property">‘<code
5577 class=property>font-feature-settings</code>’</a> property.
5578 </ol>
5580 <p>This ordering allows authors to set up a general set of defaults for
5581 fonts within their <a
5582 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5583 them with property settings for specific elements. General property
5584 settings override the settings in <a
5585 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5586 font feature settings override <a href="#propdef-font-variant"
5587 title="font-variant!!property">‘<code
5588 class=property>font-variant</code>’</a> property settings.
5590 <p>For situations where the combined list of font feature settings contains
5591 more than one value for the same feature, the last value is used. When a
5592 font lacks support for a given underlying font feature, text is simply
5593 rendered as if that font feature was not enabled; font fallback does not
5594 occur and no attempt is made to synthesize the feature except where
5595 explicitly defined for specific properties.
5597 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5598 precedence examples</h3>
5600 <div class=example>
5601 <p>With the styles below, numbers are rendered proportionally when used
5602 within a paragraph but are shown in tabular form within tables of prices:</p>
5604 <pre>body {
5605 font-variant-numeric: proportional-nums;
5606 }
5608 table.prices td {
5609 font-variant-numeric: tabular-nums;
5610 }
5611 </pre>
5612 </div>
5614 <div class=example>
5615 <p>When the <a href="#descdef-font-variant"
5616 title="font-variant!!descriptor">font-variant</a> descriptor is used
5617 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5618 it only applies to the font defined by that rule.</p>
5620 <pre>@font-face {
5621 font-family: MainText;
5622 src: url(http://example.com/font.ttf);
5623 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5624 }
5626 body {
5627 font-family: MainText, Helvetica;
5628 }
5630 table.prices td {
5631 font-variant-numeric: tabular-nums;
5632 }
5633 </pre>
5635 <p>In this case, old-style numerals will be used throughout but only where
5636 the font "MainText" is used. Just as in the previous example, tabular
5637 values will be used in price tables since ‘<a
5638 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5639 appears in a general style rule and its use is mutually exclusive with
5640 ‘<a href="#proportional-nums"><code
5641 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5642 will only be used where MainText is used.</p>
5643 </div>
5645 <div class=example>
5646 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5647 also be used to access font features in locally available fonts via the
5648 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5649 class=property>src</code></a>’ descriptor of the <a
5650 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5652 <pre>@font-face {
5653 font-family: BodyText;
5654 src: local("HiraMaruPro-W4");
5655 font-variant: proportional-width;
5656 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5657 }
5659 body { font-family: BodyText, serif; }
5660 </pre>
5662 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5663 text rendering occurs, Japanese kana will be proportionally spaced and
5664 Latin text will be italicised. Text rendered with the fallback serif font
5665 will use default rendering properties.</p>
5666 </div>
5668 <div class=example>
5669 <p>In the example below, discretionary ligatures are enabled only for a
5670 downloadable font but are disabled within spans of class "special":</p>
5672 <pre>@font-face {
5673 font-family: main;
5674 src: url(fonts/ffmeta.woff) format("woff");
5675 font-variant: discretionary-ligatures;
5676 }
5678 body { font-family: main, Helvetica; }
5679 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5680 </pre>
5682 <p>Suppose one adds a rule using ‘<code
5683 class=property>font-feature-settings</code>’ to enable discretionary
5684 ligatures:</p>
5686 <pre>body { font-family: main, Helvetica; }
5687 span { font-feature-settings: "dlig"; }
5688 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5689 </pre>
5691 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5692 spans of class "special". This is because both the <a
5693 href="#propdef-font-feature-settings"
5694 title="font-feature-settings!!property">‘<code
5695 class=property>font-feature-settings</code>’</a> and ‘<a
5696 href="#propdef-font-variant-ligatures"><code
5697 class=property>font-variant-ligatures</code></a>’ properties apply to
5698 these spans. Although the ‘<code class=css>no-discretionary
5699 ligatures</code>’ setting of ‘<a
5700 href="#propdef-font-variant-ligatures"><code
5701 class=property>font-variant-ligatures</code></a>’ effectively disables
5702 the OpenType <span class=tag>dlig</span> feature, because the <a
5703 href="#propdef-font-feature-settings"
5704 title="font-feature-settings!!property">‘<code
5705 class=property>font-feature-settings</code>’</a> is resolved after
5706 that, the ‘<code class=property>dlig</code>’ value reenables
5707 discretionary ligatures.</p>
5708 </div>
5710 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5712 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5713 and <a
5714 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5715 rules can be accessed via the following extensions to the CSS Object
5716 Model.
5718 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5719 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5721 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5722 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5724 <pre class=idl>
5725 interface CSSFontFaceRule : CSSRule {
5726 attribute DOMString family;
5727 attribute DOMString src;
5728 attribute DOMString style;
5729 attribute DOMString weight;
5730 attribute DOMString stretch;
5731 attribute DOMString unicodeRange;
5732 attribute DOMString variant;
5733 attribute DOMString featureSettings;
5734 }</pre>
5736 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5737 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5738 defined a different variant of this rule. This definition supercedes that
5739 one.
5741 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5742 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5743 interface</h3>
5745 <p>The <code>CSSRule</code> interface is extended as follows:
5747 <pre class=idl>partial interface CSSRule {
5748 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5749 }</pre>
5751 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5752 interface represents a <a
5753 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5754 rule.
5756 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5757 readonly attribute DOMString familyList;
5758 readonly attribute DOMString valueText;
5759 };</pre>
5761 <dl class=idl-attributes>
5762 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5764 <dd>The list of one or more font families for which a given set of feature
5765 values is defined.
5767 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5769 <dd>Serialized set of feature values.
5770 </dl>
5772 <p class=issue>This needs to be reworked along the lines of <a
5773 href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
5774 proposal</a> for a rule containing a family list and map objects for each
5775 of the feature types.
5777 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5778 properties to CSS properties</h2>
5780 <p><em>This appendix is included as background for some of the problems and
5781 situations that are described in other sections. It should be viewed as
5782 informative only.</em>
5784 <p>Font properties in CSS are designed to be independent of the underlying
5785 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5786 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5787 are facets of the TrueType and OpenType formats that often cause confusion
5788 for authors and present challenges to implementers on different platforms.
5790 <p>Originally developed at Apple, TrueType was designed as an outline font
5791 format for both screen and print. Microsoft joined Apple in developing the
5792 TrueType format and both platforms have supported TrueType fonts since
5793 then. Font data in the TrueType format consists of a set of tables
5794 distinguished with common four-letter tag names, each containing a
5795 specific type of data. For example, naming information, including
5796 copyright and license information, is stored in the ‘<code
5797 class=property>name</code>’ table. The <a
5798 href="#character-map"><em>character map</em></a> (‘<code
5799 class=property>cmap</code>’) table contains a mapping of character
5800 encodings to glyphs. Apple later added additional tables for supporting
5801 enhanced typographic functionality; these are now called Apple Advanced
5802 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5803 tables for advanced typography and called their format OpenType <a
5804 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5806 <p>In many cases the font data used under Microsoft Windows or Linux is
5807 slightly different from the data used under Apple's Mac OS X because the
5808 TrueType format allowed for explicit variation across platforms. This
5809 includes font metrics, names and <a href="#character-map"><em>character
5810 map</em></a> data.
5812 <p>Specifically, font family name data is handled differently across
5813 platforms. For TrueType and OpenType fonts these names are contained in
5814 the ‘<code class=property>name</code>’ table, in name records with
5815 name ID 1. Mulitple names can be stored for different locales, but
5816 Microsoft recommends fonts always include at least a US English version of
5817 the name. On Windows, Microsoft made the decision for backwards
5818 compatibility to limit this family name to a maximum of four faces; for
5819 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5820 ID 21) can be used. Other platforms such as OSX don't have this
5821 limitation, so the family name is used to define all possible groupings.
5823 <p>Other name table data provides names used to uniquely identify a
5824 specific face within a family. The full font name (name ID 4) and the
5825 Postscript name (name ID 6) describe a single face uniquely. For example,
5826 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5827 and a Postscript name of "GillSans-Bold". There can be multiple localized
5828 versions of the fullname for a given face, but the Postscript name is
5829 always a unique name made from a limited set of ASCII characters.
5831 <p>On various platforms, different names are used to search for a font. For
5832 example, with the Windows GDI CreateIndirectFont API, either a family or
5833 fullname can be used to lookup a face, while on Mac OS X the
5834 CTFontCreateWithName API call is used to lookup a given face using the
5835 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5836 to be searched using any of these names. In situations where platform
5837 API's automatically substitute other font choices, it may be necessary to
5838 verify a returned font matches a given name.
5840 <p>The weight of a given face can be determined via the usWeightClass field
5841 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5842 the width can be determined via the usWidthClass of the OS/2 table or
5843 inferred from the style name. For historical reasons related to synthetic
5844 bolding at weights 200 or lower with the Windows GDI API, font designers
5845 have sometimes skewed values in the OS/2 table to avoid these weights.
5847 <p>Rendering complex scripts that use contextual shaping such as Thai,
5848 Arabic and Devanagari requires features present only in OpenType or AAT
5849 fonts. Currently, complex script rendering is supported on Windows and
5850 Linux using OpenType font features while both OpenType and AAT font
5851 features are used under Mac OS X.
5853 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5855 <h3 class=no-num id=recent-changes> Changes from the <a
5856 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5857 CSS3 Fonts Working Draft</a></h3>
5859 <p>Major changes include:
5861 <ul>
5862 <li>Moved font load events into a separate <a
5863 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5865 <li>Tightened syntax rules for <a
5866 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5867 rules
5869 <li>Added grammar productions for <a
5870 href="#at-font-face-rule"><code>@font-face</code></a> and <a
5871 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5872 rules
5874 <li>Tightened definition of synthetic oblique
5876 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5877 class=property>unicode-range</code></a>’ descriptor
5879 <li>Detailed font matching of composite faces
5880 </ul>
5882 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5884 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5885 their help and feedback. John Hudson was kind enough to take the time to
5886 explain the subtleties of OpenType language tags and provided the example
5887 of character variant usage for displaying text on Byzantine seals. Ken
5888 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5889 and Unicode variation selectors. The idea for supporting font features by
5890 using <a href="#propdef-font-variant"
5891 title="font-variant!!property">‘<code
5892 class=property>font-variant</code>’</a> subproperties originated with
5893 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5894 of the initial design ideas for the <a
5895 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5896 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5897 in the discretionary ligatures example.
5899 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5900 that is <em>The Elements of Typographic Style</em>.
5902 <h2 class=no-num id=conformance> Conformance</h2>
5904 <h3 class=no-num id=conventions> Document Conventions</h3>
5906 <p>Conformance requirements are expressed with a combination of descriptive
5907 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5908 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5909 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5910 normative parts of this document are to be interpreted as described in RFC
5911 2119. However, for readability, these words do not appear in all uppercase
5912 letters in this specification.
5914 <p>All of the text of this specification is normative except sections
5915 explicitly marked as non-normative, examples, and notes. <a
5916 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5918 <p>Examples in this specification are introduced with the words “for
5919 example” or are set apart from the normative text with
5920 <code>class="example"</code>, like this:
5922 <div class=example>
5923 <p>This is an example of an informative example.
5924 </div>
5926 <p>Informative notes begin with the word “Note” and are set apart from
5927 the normative text with <code>class="note"</code>, like this:
5929 <p class=note>Note, this is an informative note.
5931 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5933 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5934 classes:
5936 <dl>
5937 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5938 sheet</dfn>
5940 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5941 style sheet</a>.
5943 <dt><dfn id=renderer>renderer</dfn>
5945 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5946 that interprets the semantics of a style sheet and renders documents that
5947 use them.
5949 <dt><dfn id=authoring-tool>authoring tool</dfn>
5951 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5952 that writes a style sheet.
5953 </dl>
5955 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5956 declarations that use properties defined in this module have values that
5957 are valid according to the generic CSS grammar and the individual grammars
5958 of each property as given in this module.
5960 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5961 interpreting the style sheet as defined by the appropriate specifications,
5962 it supports all the features defined by CSS Fonts Level 3 Module by
5963 parsing them correctly and rendering the document accordingly. However,
5964 the inability of a UA to correctly render a document due to limitations of
5965 the device does not make the UA non-conformant. (For example, a UA is not
5966 required to render color on a monochrome monitor.)
5968 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5969 style sheets that are syntactically correct according to the generic CSS
5970 grammar and the individual grammars of each feature in this module, and
5971 meet all other conformance requirements of style sheets as described in
5972 this module.
5974 <h3 class=no-num id=partial> Partial Implementations</h3>
5976 <p>So that authors can exploit the forward-compatible parsing rules to
5977 assign fallback values, CSS renderers <strong>must</strong> treat as
5978 invalid (and <a
5979 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5980 appropriate</a>) any at-rules, properties, property values, keywords, and
5981 other syntactic constructs for which they have no usable level of support.
5982 In particular, user agents <strong>must not</strong> selectively ignore
5983 unsupported component values and honor supported values in a single
5984 multi-value property declaration: if any value is considered invalid (as
5985 unsupported values must be), CSS requires that the entire declaration be
5986 ignored.
5988 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5990 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5991 reserves a <a
5992 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
5993 syntax</a> for proprietary and experimental extensions to CSS.
5995 <p>Prior to a specification reaching the Candidate Recommendation stage in
5996 the W3C process, all implementations of a CSS feature are considered
5997 experimental. The CSS Working Group recommends that implementations use a
5998 vendor-prefixed syntax for such features, including those in W3C Working
5999 Drafts. This avoids incompatibilities with future changes in the draft.
6001 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
6003 <p>Once a specification reaches the Candidate Recommendation stage,
6004 non-experimental implementations are possible, and implementors should
6005 release an unprefixed implementation of any CR-level feature they can
6006 demonstrate to be correctly implemented according to spec.
6008 <p>To establish and maintain the interoperability of CSS across
6009 implementations, the CSS Working Group requests that non-experimental CSS
6010 renderers submit an implementation report (and, if necessary, the
6011 testcases used for that implementation report) to the W3C before releasing
6012 an unprefixed implementation of any CSS features. Testcases submitted to
6013 W3C are subject to review and correction by the CSS Working Group.
6015 <p>Further information on submitting testcases and implementation reports
6016 can be found from on the CSS Working Group's website at <a
6017 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
6018 Questions should be directed to the <a
6019 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
6020 mailing list.
6022 <h2 class=no-num id=references>References</h2>
6024 <h3 class=no-num id=normative-references>Normative References</h3>
6025 <!--begin-normative-->
6026 <!-- Sorted by label -->
6028 <dl class=bibliography>
6029 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6030 <!---->
6032 <dt id=CHARMOD>[CHARMOD]
6034 <dd>Martin J. Dürst; et al. <a
6035 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6036 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6037 2005. W3C Recommendation. URL: <a
6038 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6039 </dd>
6040 <!---->
6042 <dt id=CORS>[CORS]
6044 <dd>Anne van Kesteren. <a
6045 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6046 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6047 Recommendation. (Work in progress.) URL: <a
6048 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6049 </dd>
6050 <!---->
6052 <dt id=CSS21>[CSS21]
6054 <dd>Bert Bos; et al. <a
6055 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6056 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6057 2011. W3C Recommendation. URL: <a
6058 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6059 </dd>
6060 <!---->
6062 <dt id=CSS3VAL>[CSS3VAL]
6064 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6065 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
6066 Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6067 Recommendation. (Work in progress.) URL: <a
6068 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
6069 </dd>
6070 <!---->
6072 <dt id=HTML5>[HTML5]
6074 <dd>Ian Hickson. <a
6075 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
6076 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
6077 <a
6078 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
6079 </dd>
6080 <!---->
6082 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6084 <dd><a
6085 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
6086 technology — Coding of audio-visual objects — Part 22: Open Font
6087 Format.</cite></a> International Organization for Standardization.
6088 ISO/IEC 14496-22:2009. URL: <a
6089 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip</a>
6090 </dd>
6091 <!---->
6093 <dt id=OPENTYPE>[OPENTYPE]
6095 <dd><a
6096 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6097 specification.</cite></a> Microsoft. URL: <a
6098 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6099 </dd>
6100 <!---->
6102 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6104 <dd><a
6105 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6106 feature registry.</cite></a> Microsoft. URL: <a
6107 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6108 </dd>
6109 <!---->
6111 <dt id=RFC2119>[RFC2119]
6113 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6114 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6115 RFC 2119. URL: <a
6116 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6117 </dd>
6118 <!---->
6120 <dt id=UAX15>[UAX15]
6122 <dd>Mark Davis; Ken Whistler. <a
6123 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6124 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6125 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6126 </dd>
6127 <!---->
6129 <dt id=UAX29>[UAX29]
6131 <dd>Mark Davis. <a
6132 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6133 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6134 URL: <a
6135 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6136 </dd>
6137 <!---->
6139 <dt id=UNICODE6>[UNICODE6]
6141 <dd>The Unicode Consortium. <a
6142 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6143 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6144 Version 6.2.0 URL: <a
6145 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6146 </dd>
6147 <!---->
6148 </dl>
6149 <!--end-normative-->
6150 <!--{{!CSS21}}-->
6151 <!--{{!CSS3VAL}}-->
6152 <!--{{!OPENTYPE}}-->
6153 <!--{{!OPENTYPE-FEATURES}}-->
6154 <!--{{!OPEN-FONT-FORMAT}}-->
6155 <!--{{!UNICODE6}}-->
6156 <!--{{!UAX15}}-->
6157 <!--{{!UAX29}}-->
6158 <!--{{!CORS}}-->
6159 <!--{{!HTML5}}-->
6160 <!--{{!CHARMOD}}-->
6162 <h3 class=no-num id=other-references>Other References</h3>
6163 <!--begin-informative-->
6164 <!-- Sorted by label -->
6166 <dl class=bibliography>
6167 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6168 <!---->
6170 <dt id=AAT-FEATURES>[AAT-FEATURES]
6172 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6173 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6174 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6175 </dd>
6176 <!---->
6178 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6180 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6181 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6182 <!---->
6184 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6186 <dd>François Yergeau; et al. <a
6187 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6188 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6189 W3C Working Draft. (Work in progress.) URL: <a
6190 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6191 </dd>
6192 <!---->
6194 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6196 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6197 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6198 <!---->
6200 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6202 <dd>L. David Baron. <a
6203 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6204 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6205 Recommendation. (Work in progress.) URL: <a
6206 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6207 </dd>
6208 <!---->
6210 <dt id=CSS3TEXT>[CSS3TEXT]
6212 <dd>Elika J. Etemad; Koji Ishii. <a
6213 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6214 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6215 progress.) URL: <a
6216 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6217 </dd>
6218 <!---->
6220 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6222 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6223 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6224 ISBN 0-201-17633-5.</dd>
6225 <!---->
6227 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6229 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6230 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6231 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6232 2000. W3C Recommendation. URL: <a
6233 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>
6234 </dd>
6235 <!---->
6237 <dt id=ELEMTYPO>[ELEMTYPO]
6239 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6240 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6241 <!---->
6243 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6245 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6246 ISBN 1-932026-01-0.</dd>
6247 <!---->
6249 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6251 <dd><a
6252 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6253 User Guide.</cite></a> FontShop International. URL: <a
6254 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6255 </dd>
6256 <!---->
6258 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6260 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6261 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6262 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6263 <!---->
6265 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6267 <dd>John Hudson. <a
6268 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6269 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6270 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6271 </dd>
6272 <!---->
6273 </dl>
6274 <!--end-informative-->
6275 <!--{{ARABIC-TYPO}}-->
6276 <!--{{CJKV-INFO-PROCESSING}}-->
6277 <!--{{DIGITAL-TYPOGRAPHY}}-->
6278 <!--{{DOM-LEVEL-2-STYLE}}-->
6279 <!--{{ELEMTYPO}}-->
6280 <!--{{LANGCULTTYPE}}-->
6281 <!--{{OPENTYPE-FONT-GUIDE}}-->
6282 <!--{{RASTER-TRAGEDY}}-->
6283 <!--{{WINDOWS-GLYPH-PROC}}-->
6284 <!--{{CHARMOD-NORM}}-->
6285 <!--{{AAT-FEATURES}}-->
6286 <!--{{CSS3-CONDITIONAL}}-->
6287 <!--{{CSS3TEXT}}-->
6289 <h2 class=no-num id=index>Index</h2>
6290 <!--begin-index-->
6292 <ul class=indexlist>
6293 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6294 title="100...900 weight values"><strong>3.2</strong></a>
6296 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6297 title="<absolute-size>"><strong>3.5</strong></a>
6299 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6300 title="<common-lig-values>"><strong>6.4</strong></a>
6302 <li><var><contextual-alt-values></var>, <a
6303 href="#contextual-alt-values"
6304 title="<contextual-alt-values>"><strong>6.4</strong></a>
6306 <li><var><discretionary-lig-values></var>, <a
6307 href="#discretionary-lig-values"
6308 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6310 <li><var><east-asian-variant-values></var>, <a
6311 href="#east-asian-variant-values"
6312 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6314 <li><var><east-asian-width-values></var>, <a
6315 href="#east-asian-width-values"
6316 title="<east-asian-width-values>"><strong>6.10</strong></a>
6318 <li><var><family-name></var>, <a href="#family-name-value"
6319 title="<family-name>"><strong>3.1</strong></a>
6321 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6322 title="<feature-tag-value>"><strong>6.12</strong></a>
6324 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6325 title="<font-face-name>"><strong>4.3</strong></a>
6327 <li><var><font-variant-css21></var>, <a
6328 href="#font-variant-css21-values"
6329 title="<font-variant-css21>"><strong>3.7</strong></a>
6331 <li><var><generic-family></var>, <a href="#generic-family-value"
6332 title="<generic-family>"><strong>3.1</strong></a>
6334 <li><var><historical-lig-values></var>, <a
6335 href="#historical-lig-values"
6336 title="<historical-lig-values>"><strong>6.4</strong></a>
6338 <li><var><length></var>, <a href="#length-size-value"
6339 title="<length>"><strong>3.5</strong></a>
6341 <li><var><number></var>, <a href="#aspect-ratio-value"
6342 title="<number>"><strong>3.6</strong></a>
6344 <li><var><numeric-figure-values></var>, <a
6345 href="#numeric-figure-values"
6346 title="<numeric-figure-values>"><strong>6.7</strong></a>
6348 <li><var><numeric-fraction-values></var>, <a
6349 href="#numeric-fraction-values"
6350 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6352 <li><var><numeric-spacing-values></var>, <a
6353 href="#numeric-spacing-values"
6354 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6356 <li><var><percentage></var>, <a href="#percentage-size-value"
6357 title="<percentage>"><strong>3.5</strong></a>
6359 <li><var><relative-size></var>, <a href="#relative-size-value"
6360 title="<relative-size>"><strong>3.5</strong></a>
6362 <li><var><string></var>, <a
6363 href="#font-language-override-string-value"
6364 title="<string>"><strong>6.13</strong></a>
6366 <li><var><urange></var>, <a href="#urange-value"
6367 title="<urange>"><strong>4.5</strong></a>
6369 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6370 title="@font-face"><strong>4.1</strong></a>
6372 <li><code>@font-feature-values</code>, <a
6373 href="#at-font-feature-values-rule"
6374 title="@font-feature-values"><strong>6.9</strong></a>
6376 <li>all-petite-caps, <a href="#all-petite-caps"
6377 title=all-petite-caps><strong>6.6</strong></a>
6379 <li>all-small-caps, <a href="#all-small-caps"
6380 title=all-small-caps><strong>6.6</strong></a>
6382 <li>annotation, <a href="#annotation"
6383 title=annotation><strong>6.8</strong></a>
6385 <li>aspect value, <a href="#aspect-value0" title="aspect
6386 value"><strong>3.6</strong></a>
6388 <li>authoring tool, <a href="#authoring-tool" title="authoring
6389 tool"><strong>#</strong></a>
6391 <li>auto
6392 <ul>
6393 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6394 font-kerning"><strong>6.3</strong></a>
6396 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6397 title="auto, font-size-adjust"><strong>3.6</strong></a>
6398 </ul>
6400 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6402 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6404 <li>character map, <a href="#character-map" title="character
6405 map"><strong>5.2</strong></a>
6407 <li>character-variant, <a href="#character-variant"
6408 title=character-variant><strong>6.8</strong></a>
6410 <li>common-ligatures, <a href="#common-ligatures"
6411 title=common-ligatures><strong>6.4</strong></a>
6413 <li>composite face, <a href="#composite-face" title="composite
6414 face"><strong>5.2</strong></a>
6416 <li>condensed, <a href="#condensed"
6417 title=condensed><strong>3.3</strong></a>
6419 <li>contextual, <a href="#contextual"
6420 title=contextual><strong>6.4</strong></a>
6422 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6423 title=CSSFontFaceRule><strong>8.1</strong></a>
6425 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6426 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6428 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6429 of"><strong>#</strong></a>
6431 <li>default face, <a href="#default-face" title="default
6432 face"><strong>5.2</strong></a>
6434 <li>descriptor_declaration, <a href="#descriptordeclaration"
6435 title="descriptor_declaration"><strong>4.1</strong></a>
6437 <li>diagonal-fractions, <a href="#diagonal-fractions"
6438 title=diagonal-fractions><strong>6.7</strong></a>
6440 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6441 title=discretionary-ligatures><strong>6.4</strong></a>
6443 <li>effective character map, <a href="#effective-character-map"
6444 title="effective character map"><strong>4.5</strong></a>
6446 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6448 <li>extra-condensed, <a href="#extra-condensed"
6449 title=extra-condensed><strong>3.3</strong></a>
6451 <li>extra-expanded, <a href="#extra-expanded"
6452 title=extra-expanded><strong>3.3</strong></a>
6454 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6455 of"><strong>#</strong></a>
6457 <li>feature_type, <a href="#featuretype"
6458 title="feature_type"><strong>6.9.1</strong></a>
6460 <li>feature_value_block, <a href="#featurevalueblock"
6461 title="feature_value_block"><strong>6.9.1</strong></a>
6463 <li>feature_value_definition, <a href="#featurevaluedefinition"
6464 title="feature_value_definition"><strong>6.9.1</strong></a>
6466 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6468 <li>font specific, <a href="#font-specific" title="font
6469 specific"><strong>6.8</strong></a>
6471 <li>font-family
6472 <ul>
6473 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6474 descriptor"><strong>4.2</strong></a>
6476 <li>property, <a href="#propdef-font-family" title="font-family,
6477 property"><strong>3.1</strong></a>
6478 </ul>
6480 <li>font-feature-settings
6481 <ul>
6482 <li>descriptor, <a href="#descdef-font-feature-settings"
6483 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6485 <li>property, <a href="#propdef-font-feature-settings"
6486 title="font-feature-settings, property"><strong>6.12</strong></a>
6487 </ul>
6489 <li>font-kerning, <a href="#propdef-font-kerning"
6490 title=font-kerning><strong>6.3</strong></a>
6492 <li>font-language-override, <a href="#propdef-font-language-override"
6493 title=font-language-override><strong>6.13</strong></a>
6495 <li>font-size, <a href="#propdef-font-size"
6496 title=font-size><strong>3.5</strong></a>
6498 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6499 title=font-size-adjust><strong>3.6</strong></a>
6501 <li>font-stretch
6502 <ul>
6503 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6504 descriptor"><strong>4.4</strong></a>
6506 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6507 property"><strong>3.3</strong></a>
6508 </ul>
6510 <li>font-style
6511 <ul>
6512 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6513 descriptor"><strong>4.4</strong></a>
6515 <li>property, <a href="#propdef-font-style" title="font-style,
6516 property"><strong>3.4</strong></a>
6517 </ul>
6519 <li>font-synthesis, <a href="#propdef-font-synthesis"
6520 title=font-synthesis><strong>3.8</strong></a>
6522 <li>font-variant
6523 <ul>
6524 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6525 descriptor"><strong>4.7</strong></a>
6527 <li>property, <a href="#propdef-font-variant" title="font-variant,
6528 property"><strong>6.11</strong></a>
6529 </ul>
6531 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6532 title=font-variant-alternates><strong>6.8</strong></a>
6534 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6535 title=font-variant-caps><strong>6.6</strong></a>
6537 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6538 title=font-variant-east-asian><strong>6.10</strong></a>
6540 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6541 title=font-variant-ligatures><strong>6.4</strong></a>
6543 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6544 title=font-variant-numeric><strong>6.7</strong></a>
6546 <li>font-variant-position, <a href="#propdef-font-variant-position"
6547 title=font-variant-position><strong>6.5</strong></a>
6549 <li>font-weight
6550 <ul>
6551 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6552 descriptor"><strong>4.4</strong></a>
6554 <li>property, <a href="#propdef-font-weight" title="font-weight,
6555 property"><strong>3.2</strong></a>
6556 </ul>
6558 <li>font_face_rule, <a href="#fontfacerule"
6559 title="font_face_rule"><strong>4.1</strong></a>
6561 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6562 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6564 <li>font_family_name, <a href="#fontfamilyname"
6565 title="font_family_name"><strong>6.9.1</strong></a>
6567 <li>font_family_name_list, <a href="#fontfamilynamelist"
6568 title="font_family_name_list"><strong>6.9.1</strong></a>
6570 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6571 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6573 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6574 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6576 <li>full-width, <a href="#full-width"
6577 title=full-width><strong>6.10</strong></a>
6579 <li>historical-forms, <a href="#historical-forms"
6580 title=historical-forms><strong>6.8</strong></a>
6582 <li>historical-ligatures, <a href="#historical-ligatures"
6583 title=historical-ligatures><strong>6.4</strong></a>
6585 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6587 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6589 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6591 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6593 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6595 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6597 <li>lining-nums, <a href="#lining-nums"
6598 title=lining-nums><strong>6.7</strong></a>
6600 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6601 definition of"><strong>#</strong></a>
6603 <li>no-common-ligatures, <a href="#no-common-ligatures"
6604 title=no-common-ligatures><strong>6.4</strong></a>
6606 <li>no-contextual, <a href="#no-contextual"
6607 title=no-contextual><strong>6.4</strong></a>
6609 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6610 title=no-discretionary-ligatures><strong>6.4</strong></a>
6612 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6613 title=no-historical-ligatures><strong>6.4</strong></a>
6615 <li>none
6616 <ul>
6617 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6618 font-kerning"><strong>6.3</strong></a>
6620 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6621 title="none, font-size-adjust"><strong>3.6</strong></a>
6623 <li>font-variant, <a href="#font-variant-none-value" title="none,
6624 font-variant"><strong>6.11</strong></a>
6626 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6627 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6628 </ul>
6630 <li>normal
6631 <ul>
6632 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6633 title="normal, font-feature-settings"><strong>6.12</strong></a>
6635 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6636 font-kerning"><strong>6.3</strong></a>
6638 <li>font-language-override, <a
6639 href="#font-language-override-normal-value" title="normal,
6640 font-language-override"><strong>6.13</strong></a>
6642 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6643 font-stretch"><strong>3.3</strong></a>
6645 <li>font-style, <a href="#font-style-normal-value" title="normal,
6646 font-style"><strong>3.4</strong></a>
6648 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6649 font-variant"><strong>6.11</strong></a>
6651 <li>font-variant-alternates, <a
6652 href="#font-variant-alternates-normal-value" title="normal,
6653 font-variant-alternates"><strong>6.8</strong></a>
6655 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6656 title="normal, font-variant-caps"><strong>6.6</strong></a>
6658 <li>font-variant-east-asian, <a
6659 href="#font-variant-east-asian-normal-value" title="normal,
6660 font-variant-east-asian"><strong>6.10</strong></a>
6662 <li>font-variant-ligatures, <a
6663 href="#font-variant-ligatures-normal-value" title="normal,
6664 font-variant-ligatures"><strong>6.4</strong></a>
6666 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6667 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6669 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6670 title="normal, font-variant-position"><strong>6.5</strong></a>
6672 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6673 font-weight"><strong>3.2</strong></a>
6674 </ul>
6676 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6678 <li>oldstyle-nums, <a href="#oldstyle-nums"
6679 title=oldstyle-nums><strong>6.7</strong></a>
6681 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6683 <li>ornaments, <a href="#ornaments"
6684 title=ornaments><strong>6.8</strong></a>
6686 <li>petite-caps, <a href="#petite-caps"
6687 title=petite-caps><strong>6.6</strong></a>
6689 <li>proportional-nums, <a href="#proportional-nums"
6690 title=proportional-nums><strong>6.7</strong></a>
6692 <li>proportional-width, <a href="#proportional-width"
6693 title=proportional-width><strong>6.10</strong></a>
6695 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6697 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6699 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6700 definition of"><strong>#</strong></a>
6702 <li>semi-condensed, <a href="#semi-condensed-"
6703 title=semi-condensed><strong>3.3</strong></a>
6705 <li>semi-expanded, <a href="#semi-expanded"
6706 title=semi-expanded><strong>3.3</strong></a>
6708 <li>serif, definition of, <a href="#serif0" title="serif, definition
6709 of"><strong>#</strong></a>
6711 <li>simplified, <a href="#simplified"
6712 title=simplified><strong>6.10</strong></a>
6714 <li>slashed-zero, <a href="#slashed-zero"
6715 title=slashed-zero><strong>6.7</strong></a>
6717 <li>small-caps, <a href="#small-caps"
6718 title=small-caps><strong>6.6</strong></a>
6720 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6722 <li>stacked-fractions, <a href="#stacked-fractions"
6723 title=stacked-fractions><strong>6.7</strong></a>
6725 <li>style sheet
6726 <ul>
6727 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6728 conformance class"><strong>#</strong></a>
6729 </ul>
6731 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6733 <li>stylistic, <a href="#stylistic"
6734 title=stylistic><strong>6.8</strong></a>
6736 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6738 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6740 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6742 <li>system font fallback, <a href="#system-font-fallback" title="system
6743 font fallback"><strong>5.2</strong></a>
6745 <li>tabular-nums, <a href="#tabular-nums"
6746 title=tabular-nums><strong>6.7</strong></a>
6748 <li>titling-caps, <a href="#titling-caps"
6749 title=titling-caps><strong>6.6</strong></a>
6751 <li>traditional, <a href="#traditional"
6752 title=traditional><strong>6.10</strong></a>
6754 <li>ultra-condensed, <a href="#ultra-condensed"
6755 title=ultra-condensed><strong>3.3</strong></a>
6757 <li>ultra-expanded, <a href="#ultra-expanded"
6758 title=ultra-expanded><strong>3.3</strong></a>
6760 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6762 <li>unicode-range, <a href="#descdef-unicode-range"
6763 title=unicode-range><strong>4.5</strong></a>
6765 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6767 <li>width, <a href="#width" title=width><strong>2</strong></a>
6768 </ul>
6769 <!--end-index-->
6771 <h2 class=no-num id=property-index>Property index</h2>
6772 <!--begin-properties-->
6774 <table class=proptable>
6775 <thead>
6776 <tr>
6777 <th>Property
6779 <th>Values
6781 <th>Initial
6783 <th>Applies to
6785 <th>Inh.
6787 <th>Percentages
6789 <th>Media
6791 <tbody>
6792 <tr>
6793 <th><a class=property href="#propdef-font">font</a>
6795 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6796 <‘font-weight’> || <‘font-stretch’ ]?
6797 <‘font-size’> [ / <‘line-height’> ]?
6798 <‘font-family’> ] | caption | icon | menu | message-box |
6799 small-caption | status-bar
6801 <td>see individual properties
6803 <td>all elements
6805 <td>yes
6807 <td>see individual properties
6809 <td>visual
6811 <tr>
6812 <th><span class=property>font-family</span>
6814 <td>[ <family-name> | <generic-family> ] #
6816 <td>depends on user agent
6818 <td>all elements
6820 <td>yes
6822 <td>N/A
6824 <td>visual
6826 <tr>
6827 <th><span class=property>font-feature-settings</span>
6829 <td>normal | <feature-tag-value> #
6831 <td>normal
6833 <td>all elements
6835 <td>yes
6837 <td>N/A
6839 <td>visual
6841 <tr>
6842 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6844 <td>auto | normal | none
6846 <td>auto
6848 <td>all elements
6850 <td>yes
6852 <td>N/A
6854 <td>visual
6856 <tr>
6857 <th><a class=property
6858 href="#propdef-font-language-override">font-language-override</a>
6860 <td>normal | <string>
6862 <td>normal
6864 <td>all elements
6866 <td>yes
6868 <td>N/A
6870 <td>visual
6872 <tr>
6873 <th><a class=property href="#propdef-font-size">font-size</a>
6875 <td><absolute-size> | <relative-size> | <length> |
6876 <percentage>
6878 <td>medium
6880 <td>all elements
6882 <td>yes
6884 <td>refer to parent element's font size
6886 <td>visual
6888 <tr>
6889 <th><a class=property
6890 href="#propdef-font-size-adjust">font-size-adjust</a>
6892 <td>none | auto | <number>
6894 <td>none
6896 <td>all elements
6898 <td>yes
6900 <td>N/A
6902 <td>visual
6904 <tr>
6905 <th><span class=property>font-stretch</span>
6907 <td>normal | ultra-condensed | extra-condensed | condensed |
6908 semi-condensed | semi-expanded | expanded | extra-expanded |
6909 ultra-expanded
6911 <td>normal
6913 <td>all elements
6915 <td>yes
6917 <td>N/A
6919 <td>visual
6921 <tr>
6922 <th><span class=property>font-style</span>
6924 <td>normal | italic | oblique
6926 <td>normal
6928 <td>all elements
6930 <td>yes
6932 <td>N/A
6934 <td>visual
6936 <tr>
6937 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6939 <td>none | [ weight || style ]
6941 <td>weight style
6943 <td>all elements
6945 <td>yes
6947 <td>N/A
6949 <td>visual
6951 <tr>
6952 <th><span class=property>font-variant</span>
6954 <td>normal | none | [ <common-lig-values> ||
6955 <discretionary-lig-values> || <historical-lig-values> ||
6956 <contextual-alt-values> || stylistic(<feature-value-name>)
6957 || historical-forms || styleset(<feature-value-name> #) ||
6958 character-variant(<feature-value-name> #) ||
6959 swash(<feature-value-name>) ||
6960 ornaments(<feature-value-name>) ||
6961 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6962 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6963 <numeric-figure-values> || <numeric-spacing-values> ||
6964 <numeric-fraction-values> || ordinal || slashed-zero ||
6965 <east-asian-variant-values> || <east-asian-width-values> ||
6966 ruby ]
6968 <td>normal
6970 <td>all elements
6972 <td>yes
6974 <td>see individual properties
6976 <td>visual
6978 <tr>
6979 <th><a class=property
6980 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6982 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6983 || styleset(<feature-value-name> #) ||
6984 character-variant(<feature-value-name> #) ||
6985 swash(<feature-value-name>) ||
6986 ornaments(<feature-value-name>) ||
6987 annotation(<feature-value-name>) ]
6989 <td>normal
6991 <td>all elements
6993 <td>yes
6995 <td>N/A
6997 <td>visual
6999 <tr>
7000 <th><a class=property
7001 href="#propdef-font-variant-caps">font-variant-caps</a>
7003 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
7004 | unicase | titling-caps
7006 <td>normal
7008 <td>all elements
7010 <td>yes
7012 <td>N/A
7014 <td>visual
7016 <tr>
7017 <th><a class=property
7018 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
7020 <td>normal | [ <east-asian-variant-values> ||
7021 <east-asian-width-values> || ruby ]
7023 <td>normal
7025 <td>all elements
7027 <td>yes
7029 <td>N/A
7031 <td>visual
7033 <tr>
7034 <th><a class=property
7035 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
7037 <td>normal | none | [ <common-lig-values> ||
7038 <discretionary-lig-values> || <historical-lig-values> ||
7039 <contextual-alt-values> ]
7041 <td>normal
7043 <td>all elements
7045 <td>yes
7047 <td>N/A
7049 <td>visual
7051 <tr>
7052 <th><a class=property
7053 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7055 <td>normal | [ <numeric-figure-values> ||
7056 <numeric-spacing-values> || <numeric-fraction-values> ||
7057 ordinal || slashed-zero ]
7059 <td>normal
7061 <td>all elements
7063 <td>yes
7065 <td>N/A
7067 <td>visual
7069 <tr>
7070 <th><a class=property
7071 href="#propdef-font-variant-position">font-variant-position</a>
7073 <td>normal | sub | super
7075 <td>normal
7077 <td>all elements
7079 <td>yes
7081 <td>N/A
7083 <td>visual
7085 <tr>
7086 <th><span class=property>font-weight</span>
7088 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7089 | 700 | 800 | 900
7091 <td>normal
7093 <td>all elements
7095 <td>yes
7097 <td>N/A
7099 <td>visual
7100 </table>
7101 <!--end-properties-->
7102 <!--begin-descriptors-->
7104 <table class=proptable>
7105 <thead>
7106 <tr>
7107 <th>Descriptor
7109 <th>Value
7111 <th>Initial
7113 <th>Percentages
7115 <th>Media
7117 <tbody>
7118 <tr>
7119 <th><span class=property>font-family</span>
7121 <td><family-name>
7123 <td>N/A
7125 <tr>
7126 <th><span class=property>font-feature-settings</span>
7128 <td>normal | <feature-tag-value> #
7130 <td>normal
7132 <tr>
7133 <th><span class=property>font-stretch</span>
7135 <td>normal | ultra-condensed | extra-condensed | condensed |
7136 semi-condensed | semi-expanded | expanded | extra-expanded |
7137 ultra-expanded
7139 <td>normal
7141 <tr>
7142 <th><span class=property>font-style</span>
7144 <td>normal | italic | oblique
7146 <td>normal
7148 <tr>
7149 <th><span class=property>font-variant</span>
7151 <td>normal | none | [ <common-lig-values> ||
7152 <discretionary-lig-values> || <historical-lig-values> ||
7153 <contextual-alt-values> || stylistic(<feature-value-name>)
7154 || historical-forms || styleset(<feature-value-name> #) ||
7155 character-variant(<feature-value-name> #) ||
7156 swash(<feature-value-name>) ||
7157 ornaments(<feature-value-name>) ||
7158 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7159 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7160 <numeric-figure-values> || <numeric-spacing-values> ||
7161 <numeric-fraction-values> || ordinal || slashed-zero ||
7162 <east-asian-variant-values> || <east-asian-width-values> ||
7163 ruby ]
7165 <td>normal
7167 <tr>
7168 <th><span class=property>font-weight</span>
7170 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7172 <td>normal
7174 <tr>
7175 <th><a class=property href="#descdef-src">src</a>
7177 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7179 <td>N/A
7181 <tr>
7182 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7184 <td><urange> #
7186 <td>U+0-10FFFF
7187 </table>
7188 <!--end-descriptors-->
7189 <script type="text/javascript">
7190 window.onload = function () {
7191 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7192 var i, hiresElements = document.getElementsByClassName("hires");
7193 for (i = 0; i < hiresElements.length; i++) {
7194 var h = hiresElements[i];
7195 if (h.tagName != "IMG") continue;
7196 var src = h.getAttribute("src");
7197 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7198 h.src = src2x;
7199 }
7200 }
7201 </script>
7202 </html>
7203 <!-- Keep this comment at the end of the file
7204 Local variables:
7205 mode: sgml
7206 sgml-declaration:"~/SGML/HTML4.decl"
7207 sgml-default-doctype-name:"html"
7208 sgml-minimize-attributes:t
7209 sgml-nofill-elements:("pre" "style" "br")
7210 sgml-live-element-indicator:t
7211 sgml-omittag:nil
7212 sgml-shorttag:nil
7213 sgml-namecase-general:t
7214 sgml-general-insert-case:lower
7215 sgml-always-quote-attributes:t
7216 sgml-indent-step:nil
7217 sgml-indent-data:t
7218 sgml-parent-document:nil
7219 sgml-exposed-tags:nil
7220 sgml-local-catalogs:nil
7221 sgml-local-ecat-files:nil
7222 End:
7223 -->
7224 <!--
7226 to do:
7228 - wording of OpenType family name handling
7229 - handling combining sequences in the font matching algorithm
7230 - fix-up fi ligature example
7232 -->
