css-fonts/Fonts.html@239900bde699
css-fonts/Fonts.html
Mon, 10 Jun 2013 11:31:51 +0900
- author
- John Daggett <jdaggett@mozilla.com>
- date
- Mon, 10 Jun 2013 11:31:51 +0900
- changeset 8386
- 239900bde699
- parent 8385
- c08eb03dc645
- child 8387
- f257ff301ad8
- permissions
- -rw-r--r--
[css3-fonts] fixup CSS3 Conditional ref
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 effective <a href="#character-map"><em>character map</em></a> 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 defined via <a
3107 href="#at-font-face-rule"><code>@font-face</code></a> rules. User agents
3108 must match these names case insensitively, using the "Default Caseless
3109 Matching" algorithm outlined in the Unicode specification <a
3110 href="#UNICODE6" rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This
3111 algorithm is detailed in section 3.13 entitled "Default Case Algorithms".
3112 Specifically, the algorithm must be applied without normalizing the
3113 strings involved and without applying any language-specific tailorings.
3114 The case folding method specified by this algorithm uses the case mappings
3115 with status field ‘<code class=property>C</code>’ or ‘<code
3116 class=property>F</code>’ in the CaseFolding.txt file of the Unicode
3117 Character Database.
3119 <p class=note> Implementors should take care to verify that a given
3120 caseless string comparison implementation uses this precise algorithm and
3121 not assume that a given platform string matching routine follows it, as
3122 many of these have locale-specific behavior or use some level of string
3123 normalization.
3125 <p class=note> For authors this means that font family names are matched
3126 case insensitively, whether those names exist in a platform font or in the
3127 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3128 in a stylesheet. Authors should take care to ensure that names use a
3129 character sequence consistent with the actual font family name,
3130 particularly when using combining characters such as diacritical marks.
3131 For example, a family name that contains an uppercase A (U+0041) followed
3132 by a combining ring (U+030A) will <strong>not</strong> match a name that
3133 looks identical but which uses the precomposed lowercase a-ring character
3134 (U+00E5) instead of the combining sequence.
3136 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3137 styles</h3>
3139 <p>The procedure for choosing fonts consists of iterating over the font
3140 families determined by the font-family property, selecting a font face
3141 with the appropriate style based on other font properties and then
3142 determining whether a glyph exists for a given character. This is done
3143 using the <dfn id=character-map>character map</dfn> of the font, data
3144 which maps characters to the default glyph for that character. Codepoint
3145 sequences consisting of a base character followed by a sequence of
3146 combining characters are treated slightly differently, see the section on
3147 <a href="#cluster-matching">cluster matching</a> below.
3149 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3150 given font family is defined to be the face that would be selected if all
3151 font style properties were set to their initial value.
3153 <ol id=fontmatchingalg>
3154 <li>Using the computed font property values for a given element, the user
3155 agent starts with the first family name in the fontlist specified by the
3156 <a href="#propdef-font-family" title="font-family!!property">‘<code
3157 class=property>font-family</code>’</a> property.
3159 <li>If the family name is unquoted and is a generic family name, the user
3160 agent looks up the appropriate font family name to be used. User agents
3161 may choose the generic font family to use based on the language of the
3162 containing element or the Unicode range of the character.
3164 <li>For other family names, the user agent attempts to find the family
3165 name among fonts defined via <a
3166 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3167 among available system fonts, matching names with a case-insensitive
3168 comparison as outlined <a href="#font-family-casing">in the section
3169 above</a>. On systems containing fonts with multiple localized font
3170 family names, user agents must match any of these names independent of
3171 the underlying system locale or platform API used. If the font resources
3172 defined for a given face in an <a
3173 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3174 available or contain invalid font data, then the face should be treated
3175 as not present in the family. If no faces are present for a family
3176 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3177 rules, the family should be treated as missing; matching a platform font
3178 with the same name must not occur in this case.
3180 <li>If a font family match occurs, the user agent assembles the set of
3181 font faces in that family and then narrows the set to a single face using
3182 other font properties in the order given below:
3183 <ol id=fontstylematchingalg>
3184 <li><a href="#propdef-font-stretch"
3185 title="font-stretch!!property">‘<code
3186 class=property>font-stretch</code>’</a> is tried first. If the
3187 matching set contains faces with width values matching the <a
3188 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3189 class=property>font-stretch</code>’</a> value, faces with other width
3190 values are removed from the matching set. If there is no face that
3191 exactly matches the width value the nearest width is used instead. If
3192 the value of <a href="#propdef-font-stretch"
3193 title="font-stretch!!property">‘<code
3194 class=property>font-stretch</code>’</a> is <a
3195 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3196 class=property>normal</code>’</a> or one of the condensed values,
3197 narrower width values are checked first, then wider values. If the
3198 value of <a href="#propdef-font-stretch"
3199 title="font-stretch!!property">‘<code
3200 class=property>font-stretch</code>’</a> is one of the expanded
3201 values, wider values are checked first, followed by narrower values.
3202 Once the closest matching width has been determined by this process,
3203 faces with other widths are removed from the matching set.
3205 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3206 class=property>font-style</code>’</a> is tried next. If the value of
3207 <a href="#propdef-font-style" title="font-style!!property">‘<code
3208 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3209 class=property>italic</code></a>’, italic faces are checked first,
3210 then oblique, then normal faces. If the value is ‘<a
3211 href="#oblique"><code class=property>oblique</code></a>’, oblique
3212 faces are checked first, then italic faces and then normal faces. If
3213 the value is <a href="#font-style-normal-value"
3214 title="normal!!font-style">‘<code
3215 class=property>normal</code>’</a>, normal faces are checked first,
3216 then oblique faces, then italic faces. Faces with other style values
3217 are excluded from the matching set. User agents are permitted to
3218 distinguish between italic and oblique faces within platform font
3219 families but this is not required, they may treat all italic or oblique
3220 faces as italic faces. However, within font families defined via <a
3221 href="#at-font-face-rule"><code>@font-face</code></a> rules, italic and
3222 oblique faces must be distinguished using the value of the <a
3223 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3224 class=property>font-style</code>’</a> descriptor.
3226 <li><a href="#propdef-font-weight"
3227 title="font-weight!!property">‘<code
3228 class=property>font-weight</code>’</a> is matched next, it will
3229 always reduce the matching set to a single font face. If bolder/lighter
3230 relative weights are used, the effective weight is calculated based on
3231 the inherited weight value, as described in the definition of the <a
3232 href="#propdef-font-weight" title="font-weight!!property">‘<code
3233 class=property>font-weight</code>’</a> property. Given the desired
3234 weight and the weights of faces in the matching set after the steps
3235 above, if the desired weight is available that face matches. Otherwise,
3236 a weight is chosen using the rules below:
3237 <ul>
3238 <li>If the desired weight is less than 400, weights below the desired
3239 weight are checked in descending order followed by weights above the
3240 desired weight in ascending order until a match is found.
3242 <li>If the desired weight is greater than 500, weights above the
3243 desired weight are checked in ascending order followed by weights
3244 below the desired weight in descending order until a match is found.
3246 <li>If the desired weight is 400, 500 is checked first and then the
3247 rule for desired weights less than 400 is used.
3249 <li>If the desired weight is 500, 400 is checked first and then the
3250 rule for desired weights less than 400 is used.
3251 </ul>
3253 <li><span class=property>‘<a href="#propdef-font-size"><code
3254 class=property>font-size</code></a>’</span> must be matched within a
3255 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3256 are rounded to the nearest whole pixel, while the tolerance for
3257 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3258 by ‘<code class=property>em</code>’ values in other properties, are
3259 based on the <span class=property>‘<a href="#propdef-font-size"><code
3260 class=property>font-size</code></a>’</span> value that is used, not
3261 the one that is specified.
3262 </ol>
3264 <li>
3265 <p>If no matching face exists or the matched face does not contain a
3266 glyph for the character to be rendered, the next family name is selected
3267 and the previous two steps repeated. Glyphs from other faces in the
3268 family are not considered. The only exception is that user agents may
3269 optionally substitute a synthetic version of the <a
3270 href="#default-face"><em>default face</em></a> if that face supports a
3271 given glyph (e.g. a synthetic italic version of the regular face may be
3272 used if the italic face doesn't support glyphs for Arabic).</p>
3273 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3275 <p>If the matched font is defined via an <a
3276 href="#at-font-face-rule"><code>@font-face</code></a> rule and needs to
3277 be downloaded, the font resource is downloaded. While the download
3278 occurs, the user agent can either wait until the font is downloaded or
3279 render once with substituted font metrics and render again once the font
3280 is downloaded.</p>
3282 <li>If there are no more font families to be evaluated and no matching
3283 face has been found, then the user agent performs a <dfn
3284 id=system-font-fallback>system font fallback</dfn> procedure to find the
3285 best match for the character to be rendered. The result of this procedure
3286 may vary across user agents.
3288 <li>If a particular character cannot be displayed using any font, the user
3289 agent should indicate by some means that a character is not being
3290 displayed, displaying either a symbolic representation of the missing
3291 glyph (e.g. using a <a
3292 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3293 Font</a>) or using the missing character glyph from a default font.
3294 </ol>
3296 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3298 <p>When text contains characters such as combining diacritics, ideally the
3299 base character should be rendered using the same font as the diacritic,
3300 this assures proper placement of the diacritic. For this reason, the font
3301 matching algorithm for clusters is more specialized than the general case
3302 of matching a single character by itself. For sequences containing
3303 variation selectors, which indicate the precise glyph to be used for a
3304 given character, user agents always attempt <a
3305 href="#system-font-fallback"><em>system font fallback</em></a> to find the
3306 appropriate glyph before using the default glyph of the base character.
3308 <p>A font is considered to <em>support</em> a given character if (1) the
3309 character is contained in the font's <a
3310 href="#character-map"><em>character map</em></a> and (2) if required by
3311 the containing script, shaping information is available for that
3312 character. Some legacy fonts may include a given character in the <a
3313 href="#character-map"><em>character map</em></a> but lack the shaping
3314 information (e.g. <a
3315 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3316 layout tables</a> or <a
3317 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3318 tables</a>) necessary for correctly rendering text runs containing that
3319 character.
3321 <p>A sequence of codepoints containing combining diacritics or other
3322 modifiers is termed a grapheme cluster (see <a href="#CSS3TEXT"
3323 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3324 description). For a given cluster containing a base character, <em>b</em>
3325 and a sequence of combining characters <em>c1, c2…</em>, the entire
3326 cluster is matched using these steps:
3328 <ol>
3329 <li>For each family in the font list, a face is chosen using the style
3330 selection rules defined in the previous section.
3331 <ol>
3332 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3333 completely supported by the font, select this font for the sequence.
3335 <li>If a sequence of multiple codepoints is canonically equivalent to a
3336 single character and the font supports that character, select this font
3337 for the sequence.
3338 </ol>
3340 <li>If no font was found in the font list in step 1:
3341 <ol>
3342 <li>If <em>c1</em> is a variation selector, system fallback must be used
3343 to find a font that supports the full sequence of <em>b + c1</em>. If
3344 no font on the system supports the full sequence, match the single
3345 character <em>b</em> using the normal procedure for matching single
3346 characters and ignore the variation selector. Note: a sequence with
3347 more than one variation selector is treated as an encoding error and
3348 the trailing selectors are ignored.
3350 <li>Otherwise, the user agent may optionally use system font fallback to
3351 match a font that supports the entire cluster.
3352 </ol>
3354 <li>If no font is found in step 2, use the matching sequence from step 1
3355 to determine the longest sequence that is completely matched by a font in
3356 the font list and attempt to match the remaining combining characters
3357 separately using the rules for single characters.
3358 </ol>
3360 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3361 issues</h3>
3363 <p>The procedure above is always performed on text runs containing Unicode
3364 characters, documents using legacy encodings are assumed to have been
3365 transcoded before matching fonts. For fonts containing <a
3366 href="#character-map"><em title="character map">character maps</em></a>
3367 for both legacy encodings and Unicode, the contents of the legacy encoding
3368 <a href="#character-map"><em>character map</em></a> must have no effect on
3369 the results of the font matching process.
3371 <p>The font matching process does not assume that text runs are in either
3372 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3373 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3374 details). Layout engines often convert base character plus combining
3375 character sequences into precomposed characters if they exist. The font
3376 matching algorithm outlined here supports both ways and fonts can
3377 generally support either but variations can occur. Authors should always
3378 tailor their choice of fonts to their content, including whether that
3379 content contains normalized or denormalized character streams.
3381 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3382 the fonts in the fontlist contain a glyph for that codepoint, user agents
3383 must display some form of missing glyph symbol for that character rather
3384 than attempting <a href="#system-font-fallback"><em>system font
3385 fallback</em></a> for that codepoint. When matching the replacement
3386 character U+FFFD, user agents may skip the font matching process and
3387 immediately display some form of missing glyph symbol, they are not
3388 required to display the glyph from the font that would be selected by the
3389 font matching process.
3391 <p>In general, the fonts for a given family will all have the same or
3392 similar <a href="#character-map"><em title="character map">character
3393 maps</em></a>. The process outlined here is designed to handle even font
3394 families containing faces with widely variant <a href="#character-map"><em
3395 title="character map">character maps</em></a>. However, authors are
3396 cautioned that the use of such families can lead to unexpected results.
3398 <p>Optimizations of this process are allowed provided that an
3399 implementation behaves as if the algorithm had been followed exactly.
3400 Matching occurs in a well-defined order to insure that the results are as
3401 consistent as possible across user agents, given an identical set of
3402 available fonts and rendering technology.
3404 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3405 changes since CSS 2.1</h3>
3407 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3408 These changes were made to better reflect actual font matching behavior
3409 across user agent implementations.
3411 <p>Differences compared to the font matching algorithm in CSS 2.1:
3413 <ul>
3414 <li>The algorithm includes font-stretch matching.
3416 <li>All possible font-style matching scenarios are delineated.
3418 <li>Small-caps fonts are not matched as part of the font matching process,
3419 they are now handled via font features.
3421 <li>Unicode variation selector matching is required.
3423 <li>Cluster sequences are matched as a unit.
3424 </ul>
3426 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3427 examples</h3>
3429 <div class=example>
3430 <p>It's useful to note that the CSS selector syntax may be used to create
3431 language-sensitive typography. For example, some Chinese and Japanese
3432 characters are unified to have the same Unicode code point, although the
3433 abstract glyphs are not the same in the two languages.
3435 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3436 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3437 </pre>
3439 <p>This selects any element that has the given language - Japanese or
3440 Traditional Chinese - and uses the appropriate font.
3441 </div>
3443 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3445 <p>Modern font technologies support a variety of advanced typographic and
3446 language-specific font features. Using these features, a single font can
3447 provide glyphs for a wide range of ligatures, contextual and stylistic
3448 alternates, tabular and old-style figures, small capitals, automatic
3449 fractions, swashes, and alternates specific to a given language. To allow
3450 authors control over these font capabilities, the ‘<code
3451 class=property>font-variant</code>’ property has been expanded for CSS3.
3452 It now functions as a shorthand for a set of properties that provide
3453 control over stylistic font features.
3455 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3456 selection and positioning</h3>
3458 <p>Simple fonts used for displaying Latin text use a very basic processing
3459 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3460 which maps each character to a glyph for that character. Glyphs for
3461 subsequent characters are simply placed one after the other along a run of
3462 text. Modern font formats such as OpenType and AAT (Apple Advanced
3463 Typography) use a richer processing model. The glyph for a given character
3464 can be chosen and positioned not just based on the codepoint of the
3465 character itself, but also on adjacent characters as well as the language,
3466 script, and features enabled for the text. Font features may be required
3467 for specific scripts, or recommended as enabled by default or they might
3468 be stylistic features meant to be used under author control.
3470 <p>For a good visual overview of these features, see the <a
3471 href="#OPENTYPE-FONT-GUIDE"
3472 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3473 For a detailed description of glyph processing for OpenType fonts, see <a
3474 href="#WINDOWS-GLYPH-PROC"
3475 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3477 <p>Stylistic font features can be classified into two broad categories:
3478 ones that affect the harmonization of glyph shapes with the surrounding
3479 context, such as kerning and ligature features, and ones such as the
3480 small-caps, subscript/superscript and alternate features that affect shape
3481 selection.
3483 <p>The subproperties of <a href="#propdef-font-variant"
3484 title="font-variant!!property">‘<code
3485 class=property>font-variant</code>’</a> listed below are used to control
3486 these stylistic font features. They do not control features that are
3487 required for displaying certain scripts, such as the OpenType features
3488 used when displaying Arabic or Indic language text. They affect glyph
3489 selection and positioning, but do not affect font selection as described
3490 in the font matching section (except in cases required for compatibility
3491 with CSS 2.1).
3493 <p>To assure consistent behavior across user agents, the equivalent
3494 OpenType property settings are listed for individual properties and are
3495 normative. When using other font formats these should be used as a
3496 guideline to map CSS font feature property values to specific font
3497 features.
3499 <h3 id=language-specific-support><span class=secno>6.2
3500 </span>Language-specific display</h3>
3502 <p>OpenType also supports language-specific glyph selection and
3503 positioning, so that text can be displayed correctly in cases where the
3504 language dictates a specific display behavior. Many languages share a
3505 common script, but the shape of certain letters can vary across those
3506 languages. For example, certain Cyrillic letters have different shapes in
3507 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3508 with an explicit fi-ligature that lacks a dot on the "i". However, in
3509 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3510 important to not use this ligature or use a specialized version that
3511 contains a dot over the "i". The example below shows language-specific
3512 variations based on stylistic traditions found in Spanish, Italian and
3513 French orthography:
3515 <div class=featex><img alt="language specific forms, spanish"
3516 src=locl-1.png></div>
3518 <div class=featex><img alt="language specific forms, italian"
3519 src=locl-2.png></div>
3521 <div class=featex><img alt="language specific forms, french"
3522 src=locl-3.png></div>
3524 <p>If the content language of the element is known according to the rules
3525 of the <a
3526 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3527 language</a>, user agents are required to infer the OpenType language
3528 system from the content language and use that when selecting and
3529 positioning glyphs using an OpenType font.
3531 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3532 declare the OpenType language to be used, for example when displaying text
3533 in a given language that uses the typographic conventions of another
3534 language or when the font does not explicitly support a given language but
3535 supports a language that shares common typographic conventions. The ‘<a
3536 href="#propdef-font-language-override"><code
3537 class=property>font-language-override</code></a>’ property is used for
3538 this purpose.</p>
3539 <!-- prop: font-kerning -->
3541 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3542 href="#propdef-font-kerning">font-kerning</a> property</h3>
3544 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3545 <tbody>
3546 <tr>
3547 <td>Name:
3549 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3551 <tr>
3552 <td>Value:
3554 <td><a href="#font-kerning-auto-value"
3555 title="auto!!font-kerning">auto</a> | <a
3556 href="#font-kerning-normal-value"
3557 title="normal!!font-kerning">normal</a> | <a
3558 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3560 <tr>
3561 <td>Initial:
3563 <td>auto
3565 <tr>
3566 <td>Applies to:
3568 <td>all elements
3570 <tr>
3571 <td>Inherited:
3573 <td>yes
3575 <tr>
3576 <td>Percentages:
3578 <td>N/A
3580 <tr>
3581 <td>Media:
3583 <td>visual
3585 <tr>
3586 <td>Computed value:
3588 <td>as specified
3590 <tr>
3591 <td>Animatable:
3593 <td>no
3594 </table>
3596 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3597 property controls metric kerning, kerning that utilizes adjustment data
3598 contained in the font.
3600 <dl>
3601 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3603 <dd>Specifies that kerning is applied at the discretion of the user agent
3605 <dt><dfn id=font-kerning-normal-value
3606 title="normal!!font-kerning">normal</dfn>
3608 <dd>Specifies that kerning is applied
3610 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3612 <dd>Specifies that kerning is not applied
3613 </dl>
3615 <p>For fonts that do not include kerning data this property will have no
3616 visible effect. When rendering with OpenType fonts, the <a
3617 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3618 specification suggests that kerning be enabled by default. When kerning is
3619 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3620 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3621 instead). User agents must also support fonts that only support kerning
3622 via data contained in a <span class=tag>kern</span> font table, as
3623 detailed in the OpenType specification. If the ‘<code
3624 class=property>letter-spacing</code>’ property is defined, kerning
3625 adjustments are considered part of the default spacing and letter spacing
3626 adjustments are made after kerning has been applied.
3628 <p>When set to ‘<code class=property>auto</code>’, user agents can
3629 determine whether to apply kerning or not based on a number of factors:
3630 text size, script, or other factors that influence text processing speed.
3631 Authors who want proper kerning should use <a
3632 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3633 class=property>normal</code>’</a> to explicitly enable kerning.
3634 Likewise, some authors may prefer to disable kerning in situations where
3635 performance is more important than precise appearance. However, in
3636 well-designed modern implementations the use of kerning generally does not
3637 have a large impact on text rendering speed.</p>
3638 <!-- prop: font-variant-ligatures -->
3640 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3641 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3642 property</h3>
3644 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3645 <tbody>
3646 <tr>
3647 <td>Name:
3649 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3651 <tr>
3652 <td>Value:
3654 <td><a href="#font-variant-ligatures-normal-value"
3655 title="normal!!font-variant-ligatures">normal</a> | <a
3656 href="#font-variant-ligatures-none-value"
3657 title="none!!font-variant-ligatures">none</a> | [ <a
3658 href="#common-lig-values"><var><common-lig-values></var></a> ||
3659 <a
3660 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3661 || <a
3662 href="#historical-lig-values"><var><historical-lig-values></var></a>
3663 || <a
3664 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3665 ]
3667 <tr>
3668 <td>Initial:
3670 <td>normal
3672 <tr>
3673 <td>Applies to:
3675 <td>all elements
3677 <tr>
3678 <td>Inherited:
3680 <td>yes
3682 <tr>
3683 <td>Percentages:
3685 <td>N/A
3687 <tr>
3688 <td>Media:
3690 <td>visual
3692 <tr>
3693 <td>Computed value:
3695 <td>as specified
3697 <tr>
3698 <td>Animatable:
3700 <td>no
3701 </table>
3703 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3704 more harmonized forms.
3706 <pre
3707 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>
3709 <pre
3710 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>
3712 <pre
3713 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>
3715 <pre
3716 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>
3718 <p>Individual values have the following meanings:
3720 <dl>
3721 <dt><dfn id=font-variant-ligatures-normal-value
3722 title="normal!!font-variant-ligatures">normal</dfn>
3724 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3725 title="normal!!font-variant-ligatures">‘<code
3726 class=property>normal</code>’</a> specifies that common default
3727 features are enabled, <a href="#font-feature-resolution">as described in
3728 detail in the next section</a>. For OpenType fonts, common ligatures and
3729 contextual forms are on by default, discretionary and historical
3730 ligatures are not.
3732 <dt><dfn id=font-variant-ligatures-none-value
3733 title="none!!font-variant-ligatures">none</dfn>
3735 <dd>Specifies that all types of ligatures and contextual forms covered by
3736 this property are explicitly disabled. In situations where ligatures are
3737 not considered necessary, this may improve the speed of text rendering.
3739 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3741 <dd>Enables display of common ligatures (OpenType features: <span
3742 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3743 enabled by default.
3744 </dl>
3746 <div class=featex><img alt="common ligature example" src=liga.png></div>
3748 <dl>
3749 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3751 <dd>Disables display of common ligatures (OpenType features: <span
3752 class=tag>liga, clig</span>).
3754 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3756 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3757 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3758 decided by the type designer, so authors will need to refer to the
3759 documentation of a given font to understand which ligatures are
3760 considered discretionary.
3761 </dl>
3763 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3765 <dl>
3766 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3768 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3769 class=tag>dlig</span>).
3771 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3773 <dd>Enables display of historical ligatures (OpenType feature: <span
3774 class=tag>hlig</span>).
3775 </dl>
3777 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3779 <dl>
3780 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3782 <dd>Disables display of historical ligatures (OpenType feature: <span
3783 class=tag>hlig</span>).
3785 <dt><dfn id=contextual>contextual</dfn>
3787 <dd>Enables display of contextual alternates (OpenType feature: <span
3788 class=tag>calt</span>). Although not strictly a ligature feature, like
3789 ligatures this feature is commonly used to harmonize the shapes of glyphs
3790 with the surrounding context. For OpenType fonts, this feature is on by
3791 default.
3792 </dl>
3794 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3796 <dl>
3797 <dt><dfn id=no-contextual>no-contextual</dfn>
3799 <dd>Disables display of contextual alternates (OpenType feature: <span
3800 class=tag>calt</span>).
3801 </dl>
3803 <p>Required ligatures, needed for correctly rendering complex scripts, are
3804 not affected by the settings above, including ‘<code
3805 class=property>none</code>’ (OpenType feature: <span
3806 class=tag>rlig</span>).</p>
3807 <!-- prop: font-variant-position -->
3809 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3810 and superscript forms: the <a
3811 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3813 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3814 <tbody>
3815 <tr>
3816 <td>Name:
3818 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3820 <tr>
3821 <td>Value:
3823 <td><a href="#font-variant-position-normal-value"
3824 title="normal!!font-variant-position">normal</a> | <a
3825 href="#sub">sub</a> | <a href="#super">super</a>
3827 <tr>
3828 <td>Initial:
3830 <td>normal
3832 <tr>
3833 <td>Applies to:
3835 <td>all elements
3837 <tr>
3838 <td>Inherited:
3840 <td>yes
3842 <tr>
3843 <td>Percentages:
3845 <td>N/A
3847 <tr>
3848 <td>Media:
3850 <td>visual
3852 <tr>
3853 <td>Computed value:
3855 <td>as specified
3857 <tr>
3858 <td>Animatable:
3860 <td>no
3861 </table>
3863 <p>This property is used to enable typographic subscript and superscript
3864 glyphs. These are alternate glyphs designed within the same em-box as
3865 default glyphs and are intended to be laid out on the same baseline as the
3866 default glyphs, with no resizing or repositioning of the baseline. They
3867 are explicitly designed to match the surrounding text and to be more
3868 readable without affecting the line height.
3870 <div class=figure><img alt="comparison between real subscript glyphs and
3871 synthesized ones" src=realsubscripts.png>
3872 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3873 (bottom)
3874 </div>
3876 <p>Individual values have the following meanings:
3878 <dl>
3879 <dt><dfn id=font-variant-position-normal-value
3880 title="normal!!font-variant-position">normal</dfn>
3882 <dd>None of the features listed below are enabled.
3884 <dt><dfn id=sub>sub</dfn>
3886 <dd>Enables display of subscript variants (OpenType feature: <span
3887 class=tag>subs</span>).
3889 <dt><dfn id=super>super</dfn>
3891 <dd>Enables display of superscript variants (OpenType feature: <span
3892 class=tag>sups</span>).
3893 </dl>
3895 <p>Because of the semantic nature of subscripts and superscripts, when the
3896 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3897 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3898 given contiguous run of text, if a variant glyph is not available for all
3899 the characters in the run, simulated glyphs must be synthesized for all
3900 characters using reduced forms of the glyphs that would be used without
3901 this feature applied. This is done per run to avoid a mixture of variant
3902 glyphs and synthesized ones that would not align correctly. In the case of
3903 OpenType fonts that lack subscript or superscript glyphs for a given
3904 character, user agents must use the appropriate subscript and superscript
3905 metrics specified in the selected font's <a
3906 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3907 table</a> <a href="#OPENTYPE"
3908 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3909 and offset of the synthesized substitutes.
3911 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3912 using superscript metrics" src=superscript-alt-synth.png>
3913 <p class=caption>Superscript alternate glyph (left), synthesized
3914 superscript glyphs (middle), and incorrect mixture of the two (right)
3915 </div>
3917 <p>In situations where text decorations are only applied to runs of text
3918 containing superscript or subscript glyphs, the synthesized glyphs must be
3919 used to avoid problems with the placement of decorations.
3921 <p>In the past, user agents have used font-size and vertical-align to
3922 simulate subscripts and superscripts for the <code title="HTML sub
3923 element">sub</code> and <code title="HTML sup element">sup</code>
3924 elements. To allow a backwards compatible way of defining subscripts and
3925 superscripts, it is recommended that authors use conditional rules <a
3926 href="#CSS3-CONDITIONAL"
3927 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3928 older user agents will still render subscripts and superscripts via the
3929 older mechanism.
3931 <p>Authors should note that fonts typically only provide subscript and
3932 superscript glyphs for a subset of all characters supported by the font.
3933 For example, while subscript and superscript glyphs are often available
3934 for Latin numbers, glyphs for punctuation and letter characters are less
3935 frequently provided. The synthetic fallback rules defined for this
3936 property assure that subscripts and superscripts will always appear but
3937 the appearance may not match author expectations if the font used does not
3938 provide the appropriate alternate glyph for all characters contained in a
3939 subscript or superscript.
3941 <p>This property is not cumulative. Applying it to elements within a
3942 subscript or superscript won't nest the placement of a subscript or
3943 superscript glyph. Images contained within text runs where the value of
3944 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3945 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3946 drawn just as they would if the value was <a
3947 href="#font-variant-position-normal-value"
3948 title="normal!!font-variant-position">‘<code
3949 class=property>normal</code>’</a>.</p>
3950 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
3951 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
3953 <p>Because of these limitations, ‘<a
3954 href="#propdef-font-variant-position"><code
3955 class=property>font-variant-position</code></a>’ is not recommended for
3956 use in user agent stylesheets. Authors should use it in cases where
3957 subscripts or superscripts will only contain the narrow range of
3958 characters supported by the fonts specified.
3960 <p class=note>The variant glyphs use the same baseline as the default
3961 glyphs would use. There is no shift in the placement along the baseline,
3962 so the use of variant glyphs doesn't affect the height of the inline box
3963 or alter the height of the linebox. This makes superscript and subscript
3964 variants ideal for situations where it's important that leading remain
3965 constant, such as in multi-column layout.
3967 <div class=example>
3968 <p>A typical user agent default style for the <a class=tag
3969 href="#sub">sub</a> element:</p>
3971 <pre>sub {
3972 vertical-align: sub;
3973 font-size: smaller;
3974 line-height: normal;
3975 }
3976 </pre>
3978 <p>Using font-variant-position to specify typographic subscripts in a way
3979 that will still show subscripts in older user agents:</p>
3981 <pre>@supports ( font-variant-position: sub ) {
3983 sub {
3984 vertical-align: baseline;
3985 font-size: 100%;
3986 line-height: inherit;
3987 font-variant-position: sub;
3988 }
3990 }
3991 </pre>
3993 <p>User agents that support the ‘<a
3994 href="#propdef-font-variant-position"><code
3995 class=property>font-variant-position</code></a>’ property will select a
3996 subscript variant glyph and render this without adjusting the baseline or
3997 font-size. Older user agents will ignore the ‘<a
3998 href="#propdef-font-variant-position"><code
3999 class=property>font-variant-position</code></a>’ property definition
4000 and use the standard defaults for subscripts.</p>
4001 </div>
4002 <!-- prop: font-variant-caps -->
4004 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4005 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4007 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4008 <tbody>
4009 <tr>
4010 <td>Name:
4012 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4014 <tr>
4015 <td>Value:
4017 <td><a href="#font-variant-caps-normal-value"
4018 title="normal!!font-variant-caps">normal</a> | <a
4019 href="#small-caps">small-caps</a> | <a
4020 href="#all-small-caps">all-small-caps</a> | <a
4021 href="#petite-caps">petite-caps</a> | <a
4022 href="#all-petite-caps">all-petite-caps</a> | <a
4023 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4025 <tr>
4026 <td>Initial:
4028 <td>normal
4030 <tr>
4031 <td>Applies to:
4033 <td>all elements
4035 <tr>
4036 <td>Inherited:
4038 <td>yes
4040 <tr>
4041 <td>Percentages:
4043 <td>N/A
4045 <tr>
4046 <td>Media:
4048 <td>visual
4050 <tr>
4051 <td>Computed value:
4053 <td>as specified
4055 <tr>
4056 <td>Animatable:
4058 <td>no
4059 </table>
4061 <p>This property allows the selection of alternate glyphs used for small or
4062 petite capitals or for titling. These glyphs are specifically designed to
4063 blend well with the surrounding normal glyphs, to maintain the weight and
4064 readability which suffers when text is simply resized to fit this purpose.
4066 <p>Individual values have the following meanings:
4068 <dl>
4069 <dt><dfn id=font-variant-caps-normal-value
4070 title="normal!!font-variant-caps">normal</dfn>
4072 <dd>None of the features listed below are enabled.
4074 <dt><dfn id=small-caps>small-caps</dfn>
4076 <dd>Enables display of small capitals (OpenType feature: <span
4077 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4078 uppercase letters but are reduced to the size of lowercase letters.
4079 </dl>
4081 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4083 <dl>
4084 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4086 <dd>Enables display of small capitals for both upper and lowercase letters
4087 (OpenType features: <span class=tag>c2sc, smcp</span>).
4089 <dt><dfn id=petite-caps>petite-caps</dfn>
4091 <dd>Enables display of petite capitals (OpenType feature: <span
4092 class=tag>pcap</span>).
4094 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4096 <dd>Enables display of petite capitals for both upper and lowercase
4097 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4099 <dt><dfn id=unicase>unicase</dfn>
4101 <dd>Enables display of mixture of small capitals for uppercase letters
4102 with normal lowercase letters (OpenType feature: <span
4103 class=tag>unic</span>).
4105 <dt><dfn id=titling-caps>titling-caps</dfn>
4107 <dd>Enables display of titling capitals (OpenType feature: <span
4108 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4109 use with lowercase letters. When used in all uppercase titling sequences
4110 they can appear too strong. Titling capitals are designed specifically
4111 for this situation.
4112 </dl>
4114 <p>The availability of these glyphs is based on whether a given feature is
4115 defined or not in the feature list of the font. User agents can optionally
4116 decide this on a per-script basis but should explicitly not decide this on
4117 a per-character basis.
4119 <p>Some fonts may only support a subset or none of the features described
4120 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4121 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4122 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4123 is specified but small-caps glyphs are not available for a given font,
4124 user agents should simulate a small-caps font, for example by taking a
4125 normal font and replacing the glyphs for lowercase letters with scaled
4126 versions of the glyphs for uppercase characters (replacing the glyphs for
4127 both upper and lowercase letters in the case of ‘<a
4128 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4130 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4131 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4132 width=512px>
4133 <p class=caption>Synthetic vs. real small-caps
4134 </div>
4136 <p>To match the surrounding text, a font may provide alternate glyphs for
4137 caseless characters when these features are enabled but when a user agent
4138 simulates small capitals, it must not attempt to simulate alternates for
4139 codepoints which are considered caseless.
4141 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4142 characters with small-caps, all-small-caps enabled" class=hires
4143 src=small-capitals-variations.png width=418px>
4144 <p class=caption>Caseless characters with small-caps, all-small-caps
4145 enabled
4146 </div>
4148 <p>If either ‘<a href="#petite-caps"><code
4149 class=property>petite-caps</code></a>’ or ‘<a
4150 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4151 is specified for a font that doesn't support these features, the property
4152 behaves as if ‘<a href="#small-caps"><code
4153 class=property>small-caps</code></a>’ or ‘<a
4154 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4155 respectively, had been specified. If ‘<a href="#unicase"><code
4156 class=property>unicase</code></a>’ is specified for a font that doesn't
4157 support that feature, the property behaves as if ‘<a
4158 href="#small-caps"><code class=property>small-caps</code></a>’ was
4159 applied only to lowercased uppercase letters. If ‘<a
4160 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4161 specified with a font that does not support this feature, this property
4162 has no visible effect. When simulated small capital glyphs are used, for
4163 scripts that lack uppercase and lowercase letters, ‘<a
4164 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4165 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4166 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4167 ‘<a href="#all-petite-caps"><code
4168 class=property>all-petite-caps</code></a>’ and ‘<a
4169 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4170 effect.
4172 <p>When casing transforms are used to simulate small capitals, the casing
4173 transformations must match those used for the <span
4174 class=property>‘<code class=property>text-transform</code>’</span>
4175 property.
4177 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4178 replace glyphs in a small-caps font so that the text appears in all
4179 uppercase letters.
4181 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4182 all-small-caps in acronym-laden text" class=hires
4183 src=acronym-laden-text.png width=596px>
4184 <p class=caption>Using small capitals to improve readability in
4185 acronym-laden text
4186 </div>
4188 <div class=example>
4189 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4191 <pre>blockquote { font-style: italic; }
4192 blockquote:first-line { font-variant: small-caps; }
4194 <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>
4195 </pre>
4196 </div>
4197 <!-- prop: font-variant-numeric -->
4199 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4200 formatting: the <a
4201 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4203 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4204 <tbody>
4205 <tr>
4206 <td>Name:
4208 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4210 <tr>
4211 <td>Value:
4213 <td><a href="#font-variant-numeric-normal-value"
4214 title="normal!!font-variant-numeric">normal</a> | [ <a
4215 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4216 || <a
4217 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4218 || <a
4219 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4220 || <a href="#ordinal">ordinal</a> || <a
4221 href="#slashed-zero">slashed-zero</a> ]
4223 <tr>
4224 <td>Initial:
4226 <td>normal
4228 <tr>
4229 <td>Applies to:
4231 <td>all elements
4233 <tr>
4234 <td>Inherited:
4236 <td>yes
4238 <tr>
4239 <td>Percentages:
4241 <td>N/A
4243 <tr>
4244 <td>Media:
4246 <td>visual
4248 <tr>
4249 <td>Computed value:
4251 <td>as specified
4253 <tr>
4254 <td>Animatable:
4256 <td>no
4257 </table>
4259 <p>Specifies control over numerical forms. The example below shows how some
4260 of these values can be combined to influence the rendering of tabular data
4261 with fonts that support these features. Within normal paragraph text,
4262 proportional numbers are used while tabular numbers are used so that
4263 columns of numbers line up properly:
4265 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4266 number styles" src=numberstyles.png>
4267 <p class=caption>Using number styles
4268 </div>
4270 <p>Possible combinations:
4272 <pre
4273 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>
4275 <pre
4276 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>
4278 <pre
4279 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>
4281 <p>Individual values have the following meanings:
4283 <dl>
4284 <dt><dfn id=font-variant-numeric-normal-value
4285 title="normal!!font-variant-numeric">normal</dfn>
4287 <dd>None of the features listed below are enabled.
4289 <dt><dfn id=lining-nums>lining-nums</dfn>
4291 <dd>Enables display of lining numerals (OpenType feature: <span
4292 class=tag>lnum</span>).
4294 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4296 <dd>Enables display of old-style numerals (OpenType feature: <span
4297 class=tag>onum</span>).
4299 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4301 <dd>Enables display of proportional numerals (OpenType feature: <span
4302 class=tag>pnum</span>).
4304 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4306 <dd>Enables display of tabular numerals (OpenType feature: <span
4307 class=tag>tnum</span>).
4309 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4311 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4312 class=tag>frac</span>).
4313 </dl>
4315 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4317 <dl>
4318 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4320 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4321 class=tag>afrc</span>).
4322 </dl>
4324 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4326 <dl>
4327 <dt><dfn id=ordinal>ordinal</dfn>
4329 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4330 <span class=tag>ordn</span>).
4332 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4334 <dd>Enables display of slashed zeros (OpenType feature: <span
4335 class=tag>zero</span>).
4336 </dl>
4338 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4340 <div class=example id=steak-marinade>
4341 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4342 and old-style numerals:</p>
4344 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4346 <h4>Steak marinade:</h4>
4347 <ul>
4348 <li><span class="amount">2</span> tbsp olive oil</li>
4349 <li><span class="amount">1</span> tbsp lemon juice</li>
4350 <li><span class="amount">1</span> tbsp soy sauce</li>
4351 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4352 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4353 <li>Salt &amp; pepper</li>
4354 </ul>
4356 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4357 for a few hours or overnight.</p>
4358 </pre>
4360 <p>Note that the fraction feature is only applied to values not the entire
4361 paragraph. Fonts often implement this feature using contextual rules
4362 based on the use of the slash (‘<code class=css>/</code>’) character.
4363 As such, it's not suitable for use as a paragraph-level style.</p>
4364 </div>
4365 <!-- prop: font-variant-alternates -->
4367 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4368 and swashes: the <a
4369 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4370 property</h3>
4372 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4373 <tbody>
4374 <tr>
4375 <td>Name:
4377 <td><dfn
4378 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4380 <tr>
4381 <td>Value:
4383 <td>normal | [ <a href="#stylistic"
4384 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4385 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4386 title=styleset>styleset(<feature-value-name> #)</a> || <a
4387 href="#character-variant"
4388 title=character-variant>character-variant(<feature-value-name>
4389 #)</a> || <a href="#swash"
4390 title=swash>swash(<feature-value-name>)</a> || <a
4391 href="#ornaments"
4392 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4393 href="#annotation"
4394 title=annotation>annotation(<feature-value-name>)</a> ]
4396 <tr>
4397 <td>Initial:
4399 <td>normal
4401 <tr>
4402 <td>Applies to:
4404 <td>all elements
4406 <tr>
4407 <td>Inherited:
4409 <td>yes
4411 <tr>
4412 <td>Percentages:
4414 <td>N/A
4416 <tr>
4417 <td>Media:
4419 <td>visual
4421 <tr>
4422 <td>Computed value:
4424 <td>as specified
4426 <tr>
4427 <td>Animatable:
4429 <td>no
4430 </table>
4432 <p>For any given character, fonts can provide a variety of alternate glyphs
4433 in addition to the default glyph for that character. This property
4434 provides control over the selection of these alternate glyphs.
4436 <p>For many of the property values listed below, several different
4437 alternate glyphs are available. How many alternates are available and what
4438 they represent is font-specific, so these are each marked <dfn
4439 id=font-specific>font specific</dfn> in the value definitions below.
4440 Because the nature of these alternates is font-specific, the <a
4441 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4442 rule is used to define values for a specific font family or set of
4443 families that associate a font-specific numeric
4444 <code><feature-index></code> with a custom
4445 <code><feature-value-name></code>, which is then used in this
4446 property to select specific alternates:
4448 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4450 p {
4451 font-family: Noble Script;
4452 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4453 }</pre>
4455 <p>When a particular <code><feature-value-name></code> has not been
4456 defined for a given family or for a particular feature type, the computed
4457 value must be the same as if it had been defined. However, property values
4458 that contain these undefined <code><feature-value-name></code>
4459 identifiers must be ignored when choosing glyphs.
4461 <pre>/* these two style rules are effectively the same */
4462 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4463 p { font-variant-alternates: normal; }
4464 </pre>
4466 <p>This allows values to be defined and used for a given set of font
4467 families but ignored if fallback occurs, since the font family name would
4468 be different. If a given value is outside the range supported by a given
4469 font, the value is ignored. These values never apply to generic font
4470 families.
4472 <p>Individual values have the following meanings:
4474 <dl>
4475 <dt><dfn id=font-variant-alternates-normal-value
4476 title="normal!!font-variant-alternates">normal</dfn>
4478 <dd>None of the features listed below are enabled.
4480 <dt><dfn id=historical-forms>historical-forms</dfn>
4482 <dd>Enables display of historical forms (OpenType feature: <span
4483 class=tag>hist</span>).
4484 </dl>
4486 <div class=featex><img alt="historical form example" src=hist.png></div>
4488 <dl>
4489 <dt><dfn id=stylistic
4490 title=stylistic>stylistic(<feature-value-name>)</dfn>
4492 <dd>Enables display of stylistic alternates (<a
4493 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4494 class=tag>salt <feature-index></span>).
4495 </dl>
4497 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4499 <dl>
4500 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4501 #)</dfn>
4503 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4504 specific</em></a>, OpenType feature: <span
4505 class=tag>ss<feature-index></span> OpenType currently defines <span
4506 class=tag>ss01</span> through <span class=tag>ss20</span>).
4507 </dl>
4509 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4511 <dl>
4512 <dt><dfn id=character-variant
4513 title=character-variant>character-variant(<feature-value-name>
4514 #)</dfn>
4516 <dd>Enables display of specific character variants (<a
4517 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4518 class=tag>cv<feature-index></span> OpenType currently defines <span
4519 class=tag>cv01</span> through <span class=tag>cv99</span>).
4521 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4523 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4524 specific</em></a>, OpenType feature: <span class=tag>swsh
4525 <feature-index>, cswh <feature-index></span>).
4526 </dl>
4528 <div class=featex><img alt="swash example" src=swsh.png></div>
4530 <dl>
4531 <dt><dfn id=ornaments
4532 title=ornaments>ornaments(<feature-value-name>)</dfn>
4534 <dd>Enables replacement of default glyphs with ornaments, if provided in
4535 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4536 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4537 may offer ornament glyphs as alternates for a wide collection of
4538 characters; however, displaying arbitrary characters (e.g.,
4539 alphanumerics) as ornaments is poor practice as it distorts the semantics
4540 of the data. Font designers are encouraged to encode all ornaments
4541 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4542 alternates for the bullet character (U+2022) to allow authors to select
4543 the desired glyph using ‘<a href="#ornaments"><code
4544 class=property>ornaments</code></a>’.
4545 </dl>
4547 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4549 <dl>
4550 <dt><dfn id=annotation
4551 title=annotation>annotation(<feature-value-name>)</dfn>
4553 <dd>Enables display of alternate annotation forms (<a
4554 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4555 class=tag>nalt <feature-index></span>).
4556 </dl>
4558 <div class=featex><img alt="alternate annotation form example"
4559 src=nalt.png></div>
4561 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4562 specific alternates: the <dfn id=at-font-feature-values-rule
4563 style="font-weight: inherit; font-style:
4564 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4566 <p>Several of the possible values of ‘<a
4567 href="#propdef-font-variant-alternates"><code
4568 class=property>font-variant-alternates</code></a>’ listed above are
4569 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4570 features fonts may define not just a single glyph but a set of alternate
4571 glyphs with an index to select a given alternate. Since these are font
4572 family specific, the <a
4573 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4574 rule is used to define named values for these indices for a given family.
4576 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4577 reference section</a> for a description of the interfaces used to modify
4578 these rules via the CSS Object Model.
4580 <div class=example>
4581 <p>In the case of the swash Q in the example shown above, the swash could
4582 be specified using these style rules:</p>
4584 <pre>
4586 @font-feature-values Jupiter Sans {
4587 @swash {
4588 delicate: 1;
4589 flowing: 2;
4590 }
4591 }
4593 h2 { font-family: Jupiter Sans, sans-serif; }
4595 /* show the second swash variant in h2 headings */
4596 h2:first-letter { font-variant-alternates: swash(flowing); }
4598 <h2>Quick</h2></pre>
4600 <p>When Jupiter Sans is present, the second alternate swash alternate will
4601 be displayed. When not present, no swash character will be shown, since
4602 the specific named value "flowing" is only defined for the Jupiter Sans
4603 family. The @-mark indicates the name of the property value for which a
4604 named value can be used. The name "flowing" is chosen by the author. The
4605 index that represents each alternate is defined within a given font's
4606 data.</p>
4607 </div>
4609 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4611 <p>An <a
4612 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4613 rule is composed of a list of font families followed by a block containing
4614 individual <a href="#featurevalueblock"><i
4615 title="feature_value_block">feature value blocks</i></a> that take the
4616 form of @-rules. Each block defines a set of named values for a specific
4617 font feature when a given set of font families is used. Effectively, they
4618 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4619 ⟨values⟩ are the numeric indices used for specific features defined
4620 for a given font.
4622 <p>In terms of the grammar, this specification defines the following
4623 productions:
4625 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4626 : <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>*
4627 '{' <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>*
4628 ;
4630 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4631 : <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> ]*
4632 ;
4634 <dfn id=fontfamilyname>font_family_name</dfn>
4635 : <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> ]* ]
4636 ;
4638 <dfn id=featurevalueblock>feature_value_block</dfn>
4639 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4640 '{' <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>*
4641 ;
4643 <dfn id=featuretype>feature_type</dfn>:
4644 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4645 ;
4647 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4648 : <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> ]*
4649 ;
4650 </pre>
4652 <p>The following new token is introduced:
4654 <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>;}
4655 </pre>
4657 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4658 value blocks</i></a> are handled as <a
4659 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4660 consist of everything up to the next block or semi-colon, whichever comes
4661 first.
4663 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4664 family list</i></a> is a comma-delimited list of <a
4665 href="#fontfamilyname"><i title="font_family_name">font family
4666 names</i></a> that match the definition of <a
4667 href="#family-name-value"><var><family-name></var></a> for the <a
4668 href="#propdef-font-family" title="font-family!!property">‘<code
4669 class=property>font-family</code>’</a> property. This means that only
4670 named font families are allowed, rules that include generic or system
4671 fonts in the list of font families are syntax errors. However, if a user
4672 agent defines a generic font to be a specific named font (e.g. Helvetica),
4673 the settings associated with that family name will be used. If syntax
4674 errors occur within the font family list, the entire rule must be ignored.
4676 <p>Within <a href="#featurevalueblock"><i
4677 title="feature_value_block">feature value blocks</i></a>, the <a
4678 href="#featuretype"><i title="feature_type">feature type</i></a> is
4679 ‘<code class=css>@</code>’ followed by the name of one of the <a
4680 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4681 href="#propdef-font-variant-alternates"><code
4682 class=property>font-variant-alternates</code></a>’ (e.g. <a
4683 href="#swash"><code>@swash</code></a>). The identifiers used within
4684 feature value definitions follow the rules of CSS user identifiers and are
4685 case-sensitive. They are unique only for a given set of font families and
4686 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4687 same identifier used with a different <a href="#featuretype"><i
4688 title="feature_type">feature type</i></a> is treated as a separate and
4689 distinct value. If the same identifier is defined mulitple times for a
4690 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4691 and font family, the last defined value is used. Values associated with a
4692 given identifier are limited to integer values 0 or greater.
4694 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4695 title="feature_value_definition">feature value definition</i></a>, such as
4696 invalid identifiers or values, the entire <a
4697 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4698 value definition</i></a> must be omitted, just as syntax errors in style
4699 declarations are handled. When the <a href="#featuretype"><i
4700 title="feature_type">feature type</i></a> is invalid, the entire
4701 associated <a href="#featurevalueblock"><i
4702 title="feature_value_block">feature value block</i></a> must be ignored.
4704 <div class=example>
4705 <p>Rules that are equivalent given syntax error handling:</p>
4707 <pre>@font-feature-values Bongo {
4708 @swash { ornate: 1; }
4709 annotation { boxed: 4; } /* should be @annotation! */
4710 @swash { double-loops: 1; flowing: -1; } /* negative value */
4711 @ornaments ; /* incomplete definition */
4712 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4713 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4714 }</pre>
4716 <p>The example above is equivalent to:</p>
4718 <pre>@font-feature-values Bongo {
4719 @swash { ornate: 1; }
4720 @swash { double-loops: 1; }
4721 @styleset { double-W: 14; sharp-terminals: 16 1; }
4722 }</pre>
4723 </div>
4725 <p>If multiple <a
4726 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4727 rules are defined for a given family, the resulting values definitions are
4728 the union of the definitions contained within these rules. This allows a
4729 set of named values to be defined for a given font family globally for a
4730 site and specific additions made per-page.
4732 <div class=example>
4733 <p>Using both site-wide and per-page feature values:</p>
4735 <pre>
4736 site.css:
4738 @font-feature-values Mercury Serif {
4739 @styleset {
4740 stacked-g: 3; /* "two-storey" versions of g, a */
4741 stacked-a: 4;
4742 }
4743 }
4745 page.css:
4747 @font-feature-values Mercury Serif {
4748 @styleset {
4749 geometric-m: 7; /* alternate version of m */
4750 }
4751 }
4753 body {
4754 font-family: Mercury Serif, serif;
4756 /* enable both the use of stacked g and alternate m */
4757 font-variant-alternates: styleset(stacked-g, geometric-m);
4758 }</pre>
4759 </div>
4761 <div class=example>
4762 <p>Using a commonly named value allows authors to use a single style rule
4763 to cover a set of fonts for which the underlying selector is different
4764 for each font. If either font in the example below is found, a circled
4765 number glyph will be used:</p>
4767 <pre>@font-feature-values Taisho Gothic {
4768 @annotation { boxed: 1; circled: 4; }
4769 }
4771 @font-feature-values Otaru Kisa {
4772 @annotation { circled: 1; black-boxed: 3; }
4773 }
4775 h3.title {
4776 /* circled form defined for both fonts */
4777 font-family: Taisho Gothic, Otaru Kisa;
4778 font-variant: annotation(circled);
4779 }</pre>
4780 </div>
4782 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4783 </span>Multi-valued feature value definitions</h4>
4785 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4786 href="#propdef-font-variant-alternates"><code
4787 class=property>font-variant-alternates</code></a>’ property values take
4788 a single value (e.g. ‘<a href="#swash"><code
4789 class=property>swash</code></a>’). The ‘<a
4790 href="#character-variant"><code
4791 class=property>character-variant</code></a>’ property value allows two
4792 values and ‘<a href="#styleset"><code
4793 class=property>styleset</code></a>’ allows an unlimited number.
4795 <p>For the styleset property value, multiple values indicate the style sets
4796 to be enabled. Values between 1 and 99 enable OpenType features <span
4797 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4798 OpenType standard only officially defines <span class=tag>ss01</span>
4799 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4800 than 99 or equal to 0 do not generate a syntax error when parsed but
4801 enable no OpenType features.
4803 <pre>@font-feature-values Mars Serif {
4804 @styleset {
4805 alt-g: 1; /* implies ss01 = 1 */
4806 curly-quotes: 3; /* implies ss03 = 1 */
4807 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4808 }
4810 @styleset {
4811 dumb: 125; /* >99, ignored */
4812 }
4814 @swash {
4815 swishy: 3 5; /* more than 1 value for swash, syntax error */
4816 }
4817 }
4819 p.codeblock {
4820 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4821 font-variant-alternates: styleset(curly-quotes, code);
4822 }</pre>
4824 <p>For character-variant, a single value between 1 and 99 indicates the
4825 enabling of OpenType feature <span class=tag>cv01</span> through <span
4826 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4827 to 0 are ignored but do not generate a syntax error when parsed but enable
4828 no OpenType features. When two values are listed, the first value
4829 indicates the feature used and the second the value passed for that
4830 feature. If more than two values are assigned to a given name, a syntax
4831 error occurs and the entire <a href="#featurevaluedefinition"><i
4832 title="feature_value_definition">feature value definition</i></a> is
4833 ignored.
4835 <pre>@font-feature-values MM Greek {
4836 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4837 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4838 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4839 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4840 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4841 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4842 @character-variant { silly: 105; } /* >99, ignored */
4843 @character-variant { dumb: 323 3; } /* >99, ignored */
4844 }
4846 #title {
4847 /* use the third alternate beta, first alternate gamma */
4848 font-variant-alternates: character-variant(beta-3, gamma);
4849 }
4851 p {
4852 /* zeta-2 follows zeta, implies cv20 = 2 */
4853 font-variant-alternates: character-variant(zeta, zeta-2);
4854 }
4856 .special {
4857 /* zeta follows zeta-2, implies cv20 = 3 */
4858 font-variant-alternates: character-variant(zeta-2, zeta);
4859 }</pre>
4861 <div class=figure><img alt="Matching text on Byzantine seals using
4862 character variants" src=byzantineseal.png>
4863 <p class=caption>Byzantine seal text displayed with character variants
4864 </div>
4866 <div class=example>
4867 <p>In the figure above, the text in red is rendered using a font
4868 containing character variants that mimic the character forms found on a
4869 Byzantine seal from the 8th century A.D. Two lines below is the same text
4870 displayed in a font without variants. Note the two variants for U and N
4871 used on the seal.</p>
4873 <pre>@font-feature-values Athena Ruby {
4874 @character-variant {
4875 leo-B: 2 1;
4876 leo-M: 13 3;
4877 leo-alt-N: 14 1;
4878 leo-N: 14 2;
4879 leo-T: 20 1;
4880 leo-U: 21 2;
4881 leo-alt-U: 21 4;
4882 }
4883 }
4885 p {
4886 font-variant: discretionary-ligatures,
4887 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4888 }
4890 span.alt-N {
4891 font-variant-alternates: character-variant(leo-alt-N);
4892 }
4894 span.alt-U {
4895 font-variant-alternates: character-variant(leo-alt-U);
4896 }
4898 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4900 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4901 </pre>
4902 </div>
4904 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4905 Asian text rendering: the <a
4906 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4907 property</h3>
4909 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4910 <tbody>
4911 <tr>
4912 <td>Name:
4914 <td><dfn
4915 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4917 <tr>
4918 <td>Value:
4920 <td><a href="#font-variant-east-asian-normal-value"
4921 title="normal!!font-variant-east-asian">normal</a> | [ <a
4922 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4923 || <a
4924 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4925 || <a href="#ruby">ruby</a> ]
4927 <tr>
4928 <td>Initial:
4930 <td>normal
4932 <tr>
4933 <td>Applies to:
4935 <td>all elements
4937 <tr>
4938 <td>Inherited:
4940 <td>yes
4942 <tr>
4943 <td>Percentages:
4945 <td>N/A
4947 <tr>
4948 <td>Media:
4950 <td>visual
4952 <tr>
4953 <td>Computed value:
4955 <td>as specified
4957 <tr>
4958 <td>Animatable:
4960 <td>no
4961 </table>
4963 <p>Allows control of glyph substitution and sizing in East Asian text.
4965 <pre
4966 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>
4968 <pre
4969 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>
4971 <p>Individual values have the following meanings:
4973 <dl>
4974 <dt><dfn id=font-variant-east-asian-normal-value
4975 title="normal!!font-variant-east-asian">normal</dfn>
4977 <dd>None of the features listed below are enabled.
4979 <dt><dfn id=jis78>jis78</dfn>
4981 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
4982 class=tag>jp78</span>).
4983 </dl>
4985 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
4987 <dl>
4988 <dt><dfn id=jis83>jis83</dfn>
4990 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
4991 class=tag>jp83</span>).
4993 <dt><dfn id=jis90>jis90</dfn>
4995 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
4996 class=tag>jp90</span>).
4998 <dt><dfn id=jis04>jis04</dfn>
5000 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5001 class=tag>jp04</span>).
5002 <p>The various JIS variants reflect the glyph forms defined in different
5003 Japanese national standards. Fonts generally include glyphs defined by
5004 the most recent national standard but it's sometimes necessary to use
5005 older variants, to match signage for example.</p>
5007 <dt><dfn id=simplified>simplified</dfn>
5009 <dd>Enables rendering of simplified forms (OpenType feature: <span
5010 class=tag>smpl</span>).
5012 <dt><dfn id=traditional>traditional</dfn>
5014 <dd>Enables rendering of traditional forms (OpenType feature: <span
5015 class=tag>trad</span>).
5016 </dl>
5018 <p>The ‘<a href="#simplified"><code
5019 class=property>simplified</code></a>’ and ‘<a
5020 href="#traditional"><code class=property>traditional</code></a>’ values
5021 allow control over the glyph forms for characters which have been
5022 simplified over time but for which the older, traditional form is still
5023 used in some contexts. The exact set of characters and glyph forms will
5024 vary to some degree by context for which a given font was designed.
5026 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5028 <dl>
5029 <dt><dfn id=full-width>full-width</dfn>
5031 <dd>Enables rendering of full-width variants (OpenType feature: <span
5032 class=tag>fwid</span>).
5034 <dt><dfn id=proportional-width>proportional-width</dfn>
5036 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5037 <span class=tag>pwid</span>).
5038 </dl>
5040 <div class=featex><img alt="proportionally spaced Japanese example"
5041 src=pwid.png></div>
5043 <dl>
5044 <dt><dfn id=ruby>ruby</dfn>
5046 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5047 class=tag>ruby</span>). Since ruby text is generally smaller than the
5048 associated body text, font designers can design special glyphs for use
5049 with ruby that are more readable than scaled down versions of the default
5050 glyphs. Only glyph selection is affected, there is no associated font
5051 scaling or other change that affects line layout. The red ruby text below
5052 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5053 Note the slight difference in stroke thickness.
5054 </dl>
5056 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5058 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5059 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5060 property</h3>
5062 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5063 <tbody>
5064 <tr>
5065 <td>Name:
5067 <td><dfn id=propdef-font-variant
5068 title="font-variant!!property">font-variant</dfn>
5070 <tr>
5071 <td>Value:
5073 <td><a href="#font-variant-normal-value"
5074 title="normal!!font-variant">normal</a> | <a
5075 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5076 <a href="#common-lig-values"><var><common-lig-values></var></a>
5077 || <a
5078 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5079 || <a
5080 href="#historical-lig-values"><var><historical-lig-values></var></a>
5081 || <a
5082 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5083 || <a href="#stylistic"><var
5084 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5085 href="#historical-forms"><var>historical-forms</var></a> || <a
5086 href="#styleset"><var
5087 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5088 href="#character-variant"><var
5089 title=character-variant>character-variant(<feature-value-name>
5090 #)</var></a> || <a href="#swash"><var
5091 title=swash>swash(<feature-value-name>)</var></a> || <a
5092 href="#ornaments"><var
5093 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5094 href="#annotation"><var
5095 title=annotation>annotation(<feature-value-name>)</var></a> || [
5096 <a href="#small-caps"><i>small-caps</i></a> | <a
5097 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5098 href="#petite-caps"><i>petite-caps</i></a> | <a
5099 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5100 href="#unicase"><i>unicase</i></a> | <a
5101 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5102 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5103 || <a
5104 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5105 || <a
5106 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5107 || <a href="#ordinal"><i>ordinal</i></a> || <a
5108 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5109 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5110 || <a
5111 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5112 || <a href="#ruby"><i>ruby</i></a> ]
5114 <tr>
5115 <td>Initial:
5117 <td>normal
5119 <tr>
5120 <td>Applies to:
5122 <td>all elements
5124 <tr>
5125 <td>Inherited:
5127 <td>yes
5129 <tr>
5130 <td>Percentages:
5132 <td>see individual properties
5134 <tr>
5135 <td>Media:
5137 <td>visual
5139 <tr>
5140 <td>Computed value:
5142 <td>see individual properties
5144 <tr>
5145 <td>Animatable:
5147 <td>see individual properties
5148 </table>
5150 <p>The <a href="#propdef-font-variant"
5151 title="font-variant!!property">‘<code
5152 class=property>font-variant</code>’</a> property is a shorthand for all
5153 font-variant subproperties. The value <dfn id=font-variant-normal-value
5154 title="normal!!font-variant">‘<code
5155 class=property>normal</code>’</dfn> resets all subproperties of <a
5156 href="#propdef-font-variant" title="font-variant!!property">‘<code
5157 class=property>font-variant</code>’</a> to their inital value. The <dfn
5158 id=font-variant-none-value title="none!!font-variant">‘<code
5159 class=property>none</code>’</dfn> value sets ‘<a
5160 href="#propdef-font-variant-ligatures"><code
5161 class=property>font-variant-ligatures</code></a>’ to ‘<code
5162 class=property>none</code>’ and resets all other font feature properties
5163 to their initial value. Like other shorthands, using <a
5164 href="#propdef-font-variant" title="font-variant!!property">‘<code
5165 class=property>font-variant</code>’</a> resets unspecified <a
5166 href="#propdef-font-variant" title="font-variant!!property">‘<code
5167 class=property>font-variant</code>’</a> subproperties to their initial
5168 values. It does not reset the values of either ‘<a
5169 href="#propdef-font-language-override"><code
5170 class=property>font-language-override</code></a>’ or <a
5171 href="#propdef-font-feature-settings"
5172 title="font-feature-settings!!property">‘<code
5173 class=property>font-feature-settings</code>’</a>.
5175 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5176 font feature settings control: the <a
5177 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5179 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5180 <tbody>
5181 <tr>
5182 <td>Name:
5184 <td><dfn id=propdef-font-feature-settings
5185 title="font-feature-settings!!property">font-feature-settings</dfn>
5187 <tr>
5188 <td>Value:
5190 <td><a href="#font-feature-settings-normal-value"
5191 title="normal!!font-feature-settings">normal</a> | <a
5192 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5194 <tr>
5195 <td>Initial:
5197 <td>normal
5199 <tr>
5200 <td>Applies to:
5202 <td>all elements
5204 <tr>
5205 <td>Inherited:
5207 <td>yes
5209 <tr>
5210 <td>Percentages:
5212 <td>N/A
5214 <tr>
5215 <td>Media:
5217 <td>visual
5219 <tr>
5220 <td>Computed value:
5222 <td>as specified
5224 <tr>
5225 <td>Animatable:
5227 <td>no
5228 </table>
5230 <p>This property provides low-level control over OpenType font features. It
5231 is intended as a way of providing access to font features that are not
5232 widely used but are needed for a particular use case.
5234 <p>Authors should generally use <a href="#propdef-font-variant"
5235 title="font-variant!!property">‘<code
5236 class=property>font-variant</code>’</a> and its related subproperties
5237 whenever possible and only use this property for special cases where its
5238 use is the only way of accessing a particular infrequently used font
5239 feature.
5241 <pre>/* enable small caps and use second swash alternate */
5242 font-feature-settings: "smcp", "swsh" 2;</pre>
5244 <p>A value of <dfn id=font-feature-settings-normal-value
5245 title="normal!!font-feature-settings">‘<code
5246 class=property>normal</code>’</dfn> means that no change in glyph
5247 selection or positioning occurs due to this property.
5249 <p>Feature tag values have the following syntax:
5251 <pre
5252 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5254 <p>The <string> is a case-sensitive OpenType feature tag. As
5255 specified in the OpenType specification, feature tags contain four ASCII
5256 characters. Tag strings longer or shorter than four characters, or
5257 containing characters outside the U+20–7E codepoint range are invalid.
5258 Feature tags need only match a feature tag defined in the font, so they
5259 are not limited to explicitly registered OpenType features. Fonts defining
5260 custom feature tags should follow the <a
5261 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5262 rules</a> defined in the OpenType specification <a
5263 href="#OPENTYPE-FEATURES"
5264 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5265 Feature tags not present in the font are ignored; a user agent must not
5266 attempt to synthesize fallback behavior based on these feature tags.
5268 <p>This means that explicitly disabling the <span class=tag>kern</span>
5269 feature will not affect the application of kerning data found in the
5270 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5271 associated with the <span class=tag>kern</span> feature in the ‘<code
5272 class=property>GPOS</code>’ table). Authors should use the ‘<a
5273 href="#propdef-font-kerning"><code
5274 class=property>font-kerning</code></a>’ property to explictly enable or
5275 disable kerning since this property affects both types of kerning.
5277 <p>If present, a value indicates an index used for glyph selection. An
5278 <integer> value must be 0 or greater. A value of 0 indicates that
5279 the feature is disabled. For boolean features, a value of 1 enables the
5280 feature. For non-boolean features, a value of 1 or greater enables the
5281 feature and indicates the feature selection index. A value of ‘<code
5282 class=property>on</code>’ is synonymous with 1 and ‘<code
5283 class=property>off</code>’ is synonymous with 0. If the value is
5284 omitted, a value of 1 is assumed.
5286 <pre>
5287 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5288 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5289 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5290 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5291 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5292 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5293 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5294 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5295 font-feature-settings: dlig; /* invalid, tag must be a string */
5296 </pre>
5298 <p>When values greater than the range supported by the font are specified,
5299 the behavior is explicitly undefined. For boolean features, in general
5300 these will enable the feature. For non-boolean features, out of range
5301 values will in general be equivalent to a 0 value. However, in both cases
5302 the exact behavior will depend upon the way the font is designed
5303 (specifically, which type of lookup is used to define the feature).
5305 <p>Although specifically defined for OpenType feature tags, feature tags
5306 for other modern font formats that support font features may be added in
5307 the future. Where possible, features defined for other font formats should
5308 attempt to follow the pattern of registered OpenType tags.
5310 <div class=example>
5311 <p>The Japanese text below will be rendered with half-width kana
5312 characters:</p>
5314 <pre lang=ja>
5315 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5317 <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>
5318 </pre>
5319 </div>
5321 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5322 language override: the <a
5323 href="#propdef-font-language-override">font-language-override</a> property</h3>
5325 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5326 <tbody>
5327 <tr>
5328 <td>Name:
5330 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5332 <tr>
5333 <td>Value:
5335 <td><a href="#font-language-override-normal-value"
5336 title="normal!!font-language-override">normal</a> | <a
5337 href="#font-language-override-string-value"><var><string></var></a>
5339 <tr>
5340 <td>Initial:
5342 <td><a href="#font-language-override-normal-value"
5343 title="normal!!font-language-override">normal</a>
5345 <tr>
5346 <td>Applies to:
5348 <td>all elements
5350 <tr>
5351 <td>Inherited:
5353 <td>yes
5355 <tr>
5356 <td>Percentages:
5358 <td>N/A
5360 <tr>
5361 <td>Media:
5363 <td>visual
5365 <tr>
5366 <td>Computed value:
5368 <td>as specified
5370 <tr>
5371 <td>Animatable:
5373 <td>no
5374 </table>
5376 <p>Normally, authors can control the use of language-specific glyph
5377 substitutions and positioning by setting the content language of an
5378 element, as <a href="#language-specific-support">described above</a>:
5380 <pre><!-- Display text using S'gaw Karen specific features -->
5381 <p lang="ksw">...</p></pre>
5383 <p>In some cases, authors may need to specify a language system that
5384 differs from the content language, for example due to the need to mimic
5385 another language's typographic traditions. The ‘<a
5386 href="#propdef-font-language-override"><code
5387 class=property>font-language-override</code></a>’ property allows
5388 authors to explicitly specify the language system of the font, overriding
5389 the language system implied by the content language.
5391 <p>Values have the following meanings:
5393 <dl>
5394 <dt><dfn id=font-language-override-normal-value
5395 title="normal!!font-language-override">normal</dfn>
5397 <dd>specifies that when rendering with OpenType fonts, the content
5398 language of the element is used to infer the OpenType language system
5400 <dt><dfn
5401 id=font-language-override-string-value><var><string></var></dfn>
5403 <dd>single three-letter case-sensitive OpenType <a
5404 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5405 system tag</a>, specifies the OpenType language system to be used instead
5406 of the language system implied by the language of the element
5407 </dl>
5408 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5409 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5411 <p>Use of invalid OpenType language system tags must not generate a parse
5412 error but must be ignored when doing glyph selection and placement.
5414 <div class=example>
5415 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5416 Declaration of Human Rights</a> has been translated into a wide variety
5417 of languages. In Turkish, Article 9 of this document might be marked up
5418 as below:</p>
5420 <pre lang=tr><body lang="tr">
5422 <h4>Madde 9</h4>
5423 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5424 </pre>
5426 <p>Here the user agent uses the value of the ‘<code
5427 class=property>lang</code>’ attribute when rendering text and
5428 appropriately renders this text without ‘<code
5429 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5430 href="#propdef-font-language-override"><code
5431 class=property>font-language-override</code></a>’ property.</p>
5433 <p>However, a given font may lack support for a specific language. In this
5434 situation authors may need to use the typographic conventions of a
5435 related language that are supported by that font:</p>
5437 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5439 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5441 <h4>Члeн 9</h4>
5442 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5444 </pre>
5446 <p>The Macedonian text here will be rendered using Serbian typographic
5447 conventions, with the assumption that the font specified supports
5448 Serbian.</p>
5449 </div>
5451 <p><a id=rendering-considerations></a>
5453 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5454 Resolution</h2>
5456 <p>As described in the previous section, font features can be enabled in a
5457 variety of ways, either via the use of <a href="#propdef-font-variant"
5458 title="font-variant!!property">‘<code
5459 class=property>font-variant</code>’</a> or <a
5460 href="#propdef-font-feature-settings"
5461 title="font-feature-settings!!property">‘<code
5462 class=property>font-feature-settings</code>’</a> in a style rule or
5463 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5464 The resolution order for the union of these settings is defined below.
5465 Features defined via CSS properties are applied on top of layout engine
5466 default features.
5468 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5470 <p>For OpenType fonts, user agents must enable the default features defined
5471 in the OpenType documentation for a given script and writing mode.
5472 Required ligatures, common ligatures and contextual forms must be enabled
5473 by default (OpenType features: <span class=tag>rlig, liga, clig,
5474 calt</span>), along with localized forms (OpenType feature: <span
5475 class=tag>locl</span>), and features required for proper display of
5476 composed characters and marks (OpenType features: <span class=tag>ccmp,
5477 mark, mkmk</span>). These features must always be enabled, even when the
5478 value of the <a href="#propdef-font-variant"
5479 title="font-variant!!property">‘<code
5480 class=property>font-variant</code>’</a> and <a
5481 href="#propdef-font-feature-settings"
5482 title="font-feature-settings!!property">‘<code
5483 class=property>font-feature-settings</code>’</a> properties is <span
5484 title="normal value">‘<code class=property>normal</code>’</span>.
5485 Individual features are only disabled when explicitly overridden by the
5486 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5487 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5488 href="#no-common-ligatures"><code
5489 class=property>no-common-ligatures</code></a>’. For handling complex
5490 scripts such as <a
5491 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5492 <a
5493 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5494 or <a
5495 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5496 additional features are required. For upright text within vertical text
5497 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5498 must be enabled.
5500 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5502 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5503 feature property settings are resolved in the order below, in ascending
5504 order of precedence. This ordering is used to construct a combined list of
5505 font features that affect a given text run.
5507 <ol>
5508 <li>Font features enabled by default, including features required for a
5509 given script.
5511 <li>If the font is defined via an <a
5512 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5513 features implied by the font-variant descriptor in the <a
5514 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5516 <li>If the font is defined via an <a
5517 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5518 features implied by the font-feature-settings descriptor in the <a
5519 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5521 <li>Feature settings determined by properties other than <a
5522 href="#propdef-font-variant" title="font-variant!!property">‘<code
5523 class=property>font-variant</code>’</a> or <a
5524 href="#propdef-font-feature-settings"
5525 title="font-feature-settings!!property">‘<code
5526 class=property>font-feature-settings</code>’</a>. For example, setting
5527 a non-default value for the ‘<code
5528 class=property>letter-spacing</code>’ property disables common
5529 ligatures.
5531 <li>Font features implied by the value of the <a
5532 href="#propdef-font-variant" title="font-variant!!property">‘<code
5533 class=property>font-variant</code>’</a> property, the related <a
5534 href="#propdef-font-variant" title="font-variant!!property">‘<code
5535 class=property>font-variant</code>’</a> subproperties and any other CSS
5536 property that uses OpenType features (e.g. the ‘<a
5537 href="#propdef-font-kerning"><code
5538 class=property>font-kerning</code></a>’ property).
5540 <li>Font features implied by the value of <a
5541 href="#propdef-font-feature-settings"
5542 title="font-feature-settings!!property">‘<code
5543 class=property>font-feature-settings</code>’</a> property.
5544 </ol>
5546 <p>This ordering allows authors to set up a general set of defaults for
5547 fonts within their <a
5548 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5549 them with property settings for specific elements. General property
5550 settings override the settings in <a
5551 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5552 font feature settings override <a href="#propdef-font-variant"
5553 title="font-variant!!property">‘<code
5554 class=property>font-variant</code>’</a> property settings.
5556 <p>For situations where the combined list of font feature settings contains
5557 more than one value for the same feature, the last value is used. When a
5558 font lacks support for a given underlying font feature, text is simply
5559 rendered as if that font feature was not enabled; font fallback does not
5560 occur and no attempt is made to synthesize the feature except where
5561 explicitly defined for specific properties.
5563 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5564 precedence examples</h3>
5566 <div class=example>
5567 <p>With the styles below, numbers are rendered proportionally when used
5568 within a paragraph but are shown in tabular form within tables of prices:</p>
5570 <pre>body {
5571 font-variant-numeric: proportional-nums;
5572 }
5574 table.prices td {
5575 font-variant-numeric: tabular-nums;
5576 }
5577 </pre>
5578 </div>
5580 <div class=example>
5581 <p>When the <a href="#descdef-font-variant"
5582 title="font-variant!!descriptor">font-variant</a> descriptor is used
5583 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5584 it only applies to the font defined by that rule.</p>
5586 <pre>@font-face {
5587 font-family: MainText;
5588 src: url(http://example.com/font.ttf);
5589 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5590 }
5592 body {
5593 font-family: MainText, Helvetica;
5594 }
5596 table.prices td {
5597 font-variant-numeric: tabular-nums;
5598 }
5599 </pre>
5601 <p>In this case, old-style numerals will be used throughout but only where
5602 the font "MainText" is used. Just as in the previous example, tabular
5603 values will be used in price tables since ‘<a
5604 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5605 appears in a general style rule and its use is mutually exclusive with
5606 ‘<a href="#proportional-nums"><code
5607 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5608 will only be used where MainText is used.</p>
5609 </div>
5611 <div class=example>
5612 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5613 also be used to access font features in locally available fonts via the
5614 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5615 class=property>src</code></a>’ descriptor of the <a
5616 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5618 <pre>@font-face {
5619 font-family: BodyText;
5620 src: local("HiraMaruPro-W4");
5621 font-variant: proportional-width;
5622 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5623 }
5625 body { font-family: BodyText, serif; }
5626 </pre>
5628 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5629 text rendering occurs, Japanese kana will be proportionally spaced and
5630 Latin text will be italicised. Text rendered with the fallback serif font
5631 will use default rendering properties.</p>
5632 </div>
5634 <div class=example>
5635 <p>In the example below, discretionary ligatures are enabled only for a
5636 downloadable font but are disabled within spans of class "special":</p>
5638 <pre>@font-face {
5639 font-family: main;
5640 src: url(fonts/ffmeta.woff) format("woff");
5641 font-variant: discretionary-ligatures;
5642 }
5644 body { font-family: main, Helvetica; }
5645 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5646 </pre>
5648 <p>Suppose one adds a rule using ‘<code
5649 class=property>font-feature-settings</code>’ to enable discretionary
5650 ligatures:</p>
5652 <pre>body { font-family: main, Helvetica; }
5653 span { font-feature-settings: "dlig"; }
5654 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5655 </pre>
5657 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5658 spans of class "special". This is because both the <a
5659 href="#propdef-font-feature-settings"
5660 title="font-feature-settings!!property">‘<code
5661 class=property>font-feature-settings</code>’</a> and ‘<a
5662 href="#propdef-font-variant-ligatures"><code
5663 class=property>font-variant-ligatures</code></a>’ properties apply to
5664 these spans. Although the ‘<code class=css>no-discretionary
5665 ligatures</code>’ setting of ‘<a
5666 href="#propdef-font-variant-ligatures"><code
5667 class=property>font-variant-ligatures</code></a>’ effectively disables
5668 the OpenType <span class=tag>dlig</span> feature, because the <a
5669 href="#propdef-font-feature-settings"
5670 title="font-feature-settings!!property">‘<code
5671 class=property>font-feature-settings</code>’</a> is resolved after
5672 that, the ‘<code class=property>dlig</code>’ value reenables
5673 discretionary ligatures.</p>
5674 </div>
5676 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5678 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5679 and <a
5680 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5681 rules can be accessed via the following extensions to the CSS Object
5682 Model.
5684 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5685 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5687 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5688 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5690 <pre class=idl>
5691 interface CSSFontFaceRule : CSSRule {
5692 attribute DOMString family;
5693 attribute DOMString src;
5694 attribute DOMString style;
5695 attribute DOMString weight;
5696 attribute DOMString stretch;
5697 attribute DOMString unicodeRange;
5698 attribute DOMString variant;
5699 attribute DOMString featureSettings;
5700 }</pre>
5702 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5703 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5704 defined a different variant of this rule. This definition supercedes that
5705 one.
5707 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5708 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5709 interface</h3>
5711 <p>The <code>CSSRule</code> interface is extended as follows:
5713 <pre class=idl>partial interface CSSRule {
5714 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5715 }</pre>
5717 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5718 interface represents a <a
5719 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5720 rule.
5722 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5723 readonly attribute DOMString familyList;
5724 readonly attribute DOMString valueText;
5725 };</pre>
5727 <dl class=idl-attributes>
5728 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5730 <dd>The list of one or more font families for which a given set of feature
5731 values is defined.
5733 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5735 <dd>Serialized set of feature values.
5736 </dl>
5738 <p class=issue>This needs to be reworked along the lines of <a
5739 href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
5740 proposal</a> for a rule containing a family list and map objects for each
5741 of the feature types.
5743 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5744 properties to CSS properties</h2>
5746 <p><em>This appendix is included as background for some of the problems and
5747 situations that are described in other sections. It should be viewed as
5748 informative only.</em>
5750 <p>Font properties in CSS are designed to be independent of the underlying
5751 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5752 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5753 are facets of the TrueType and OpenType formats that often cause confusion
5754 for authors and present challenges to implementers on different platforms.
5756 <p>Originally developed at Apple, TrueType was designed as an outline font
5757 format for both screen and print. Microsoft joined Apple in developing the
5758 TrueType format and both platforms have supported TrueType fonts since
5759 then. Font data in the TrueType format consists of a set of tables
5760 distinguished with common four-letter tag names, each containing a
5761 specific type of data. For example, naming information, including
5762 copyright and license information, is stored in the ‘<code
5763 class=property>name</code>’ table. The <a
5764 href="#character-map"><em>character map</em></a> (‘<code
5765 class=property>cmap</code>’) table contains a mapping of character
5766 encodings to glyphs. Apple later added additional tables for supporting
5767 enhanced typographic functionality; these are now called Apple Advanced
5768 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5769 tables for advanced typography and called their format OpenType <a
5770 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5772 <p>In many cases the font data used under Microsoft Windows or Linux is
5773 slightly different from the data used under Apple's Mac OS X because the
5774 TrueType format allowed for explicit variation across platforms. This
5775 includes font metrics, names and <a href="#character-map"><em>character
5776 map</em></a> data.
5778 <p>Specifically, font family name data is handled differently across
5779 platforms. For TrueType and OpenType fonts these names are contained in
5780 the ‘<code class=property>name</code>’ table, in name records with
5781 name ID 1. Mulitple names can be stored for different locales, but
5782 Microsoft recommends fonts always include at least a US English version of
5783 the name. On Windows, Microsoft made the decision for backwards
5784 compatibility to limit this family name to a maximum of four faces; for
5785 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5786 ID 21) can be used. Other platforms such as OSX don't have this
5787 limitation, so the family name is used to define all possible groupings.
5789 <p>Other name table data provides names used to uniquely identify a
5790 specific face within a family. The full font name (name ID 4) and the
5791 Postscript name (name ID 6) describe a single face uniquely. For example,
5792 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5793 and a Postscript name of "GillSans-Bold". There can be multiple localized
5794 versions of the fullname for a given face, but the Postscript name is
5795 always a unique name made from a limited set of ASCII characters.
5797 <p>On various platforms, different names are used to search for a font. For
5798 example, with the Windows GDI CreateIndirectFont API, either a family or
5799 fullname can be used to lookup a face, while on Mac OS X the
5800 CTFontCreateWithName API call is used to lookup a given face using the
5801 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5802 to be searched using any of these names. In situations where platform
5803 API's automatically substitute other font choices, it may be necessary to
5804 verify a returned font matches a given name.
5806 <p>The weight of a given face can be determined via the usWeightClass field
5807 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5808 the width can be determined via the usWidthClass of the OS/2 table or
5809 inferred from the style name. For historical reasons related to synthetic
5810 bolding at weights 200 or lower with the Windows GDI API, font designers
5811 have sometimes skewed values in the OS/2 table to avoid these weights.
5813 <p>Rendering complex scripts that use contextual shaping such as Thai,
5814 Arabic and Devanagari requires features present only in OpenType or AAT
5815 fonts. Currently, complex script rendering is supported on Windows and
5816 Linux using OpenType font features while both OpenType and AAT font
5817 features are used under Mac OS X.
5819 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5821 <h3 class=no-num id=recent-changes> Changes from the <a
5822 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5823 CSS3 Fonts Working Draft</a></h3>
5825 <p>Major changes include:
5827 <ul>
5828 <li>Moved font load events into a separate <a
5829 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5831 <li>Tightened syntax rules for <a
5832 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5833 rules
5835 <li>Added grammar productions for <a
5836 href="#at-font-face-rule"><code>@font-face</code></a> and <a
5837 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5838 rules
5840 <li>Tightened definition of synthetic oblique
5842 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5843 class=property>unicode-range</code></a>’ descriptor
5844 </ul>
5846 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5848 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5849 their help and feedback. John Hudson was kind enough to take the time to
5850 explain the subtleties of OpenType language tags and provided the example
5851 of character variant usage for displaying text on Byzantine seals. Ken
5852 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5853 and Unicode variation selectors. The idea for supporting font features by
5854 using <a href="#propdef-font-variant"
5855 title="font-variant!!property">‘<code
5856 class=property>font-variant</code>’</a> subproperties originated with
5857 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5858 of the initial design ideas for the <a
5859 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5860 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5861 in the discretionary ligatures example.
5863 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5864 that is <em>The Elements of Typographic Style</em>.
5866 <h2 class=no-num id=conformance> Conformance</h2>
5868 <h3 class=no-num id=conventions> Document Conventions</h3>
5870 <p>Conformance requirements are expressed with a combination of descriptive
5871 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5872 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5873 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5874 normative parts of this document are to be interpreted as described in RFC
5875 2119. However, for readability, these words do not appear in all uppercase
5876 letters in this specification.
5878 <p>All of the text of this specification is normative except sections
5879 explicitly marked as non-normative, examples, and notes. <a
5880 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5882 <p>Examples in this specification are introduced with the words “for
5883 example” or are set apart from the normative text with
5884 <code>class="example"</code>, like this:
5886 <div class=example>
5887 <p>This is an example of an informative example.
5888 </div>
5890 <p>Informative notes begin with the word “Note” and are set apart from
5891 the normative text with <code>class="note"</code>, like this:
5893 <p class=note>Note, this is an informative note.
5895 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5897 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5898 classes:
5900 <dl>
5901 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5902 sheet</dfn>
5904 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5905 style sheet</a>.
5907 <dt><dfn id=renderer>renderer</dfn>
5909 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5910 that interprets the semantics of a style sheet and renders documents that
5911 use them.
5913 <dt><dfn id=authoring-tool>authoring tool</dfn>
5915 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5916 that writes a style sheet.
5917 </dl>
5919 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5920 declarations that use properties defined in this module have values that
5921 are valid according to the generic CSS grammar and the individual grammars
5922 of each property as given in this module.
5924 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5925 interpreting the style sheet as defined by the appropriate specifications,
5926 it supports all the features defined by CSS Fonts Level 3 Module by
5927 parsing them correctly and rendering the document accordingly. However,
5928 the inability of a UA to correctly render a document due to limitations of
5929 the device does not make the UA non-conformant. (For example, a UA is not
5930 required to render color on a monochrome monitor.)
5932 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5933 style sheets that are syntactically correct according to the generic CSS
5934 grammar and the individual grammars of each feature in this module, and
5935 meet all other conformance requirements of style sheets as described in
5936 this module.
5938 <h3 class=no-num id=partial> Partial Implementations</h3>
5940 <p>So that authors can exploit the forward-compatible parsing rules to
5941 assign fallback values, CSS renderers <strong>must</strong> treat as
5942 invalid (and <a
5943 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5944 appropriate</a>) any at-rules, properties, property values, keywords, and
5945 other syntactic constructs for which they have no usable level of support.
5946 In particular, user agents <strong>must not</strong> selectively ignore
5947 unsupported component values and honor supported values in a single
5948 multi-value property declaration: if any value is considered invalid (as
5949 unsupported values must be), CSS requires that the entire declaration be
5950 ignored.
5952 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5954 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5955 reserves a <a
5956 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
5957 syntax</a> for proprietary and experimental extensions to CSS.
5959 <p>Prior to a specification reaching the Candidate Recommendation stage in
5960 the W3C process, all implementations of a CSS feature are considered
5961 experimental. The CSS Working Group recommends that implementations use a
5962 vendor-prefixed syntax for such features, including those in W3C Working
5963 Drafts. This avoids incompatibilities with future changes in the draft.
5965 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
5967 <p>Once a specification reaches the Candidate Recommendation stage,
5968 non-experimental implementations are possible, and implementors should
5969 release an unprefixed implementation of any CR-level feature they can
5970 demonstrate to be correctly implemented according to spec.
5972 <p>To establish and maintain the interoperability of CSS across
5973 implementations, the CSS Working Group requests that non-experimental CSS
5974 renderers submit an implementation report (and, if necessary, the
5975 testcases used for that implementation report) to the W3C before releasing
5976 an unprefixed implementation of any CSS features. Testcases submitted to
5977 W3C are subject to review and correction by the CSS Working Group.
5979 <p>Further information on submitting testcases and implementation reports
5980 can be found from on the CSS Working Group's website at <a
5981 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
5982 Questions should be directed to the <a
5983 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
5984 mailing list.
5986 <h2 class=no-num id=references>References</h2>
5988 <h3 class=no-num id=normative-references>Normative References</h3>
5989 <!--begin-normative-->
5990 <!-- Sorted by label -->
5992 <dl class=bibliography>
5993 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
5994 <!---->
5996 <dt id=CHARMOD>[CHARMOD]
5998 <dd>Martin J. Dürst; et al. <a
5999 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6000 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6001 2005. W3C Recommendation. URL: <a
6002 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6003 </dd>
6004 <!---->
6006 <dt id=CORS>[CORS]
6008 <dd>Anne van Kesteren. <a
6009 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6010 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6011 Recommendation. (Work in progress.) URL: <a
6012 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6013 </dd>
6014 <!---->
6016 <dt id=CSS21>[CSS21]
6018 <dd>Bert Bos; et al. <a
6019 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6020 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6021 2011. W3C Recommendation. URL: <a
6022 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6023 </dd>
6024 <!---->
6026 <dt id=CSS3VAL>[CSS3VAL]
6028 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6029 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
6030 Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6031 Recommendation. (Work in progress.) URL: <a
6032 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
6033 </dd>
6034 <!---->
6036 <dt id=HTML5>[HTML5]
6038 <dd>Ian Hickson. <a
6039 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
6040 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
6041 <a
6042 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
6043 </dd>
6044 <!---->
6046 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6048 <dd><a
6049 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
6050 technology — Coding of audio-visual objects — Part 22: Open Font
6051 Format.</cite></a> International Organization for Standardization.
6052 ISO/IEC 14496-22:2009. URL: <a
6053 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>
6054 </dd>
6055 <!---->
6057 <dt id=OPENTYPE>[OPENTYPE]
6059 <dd><a
6060 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6061 specification.</cite></a> Microsoft. URL: <a
6062 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6063 </dd>
6064 <!---->
6066 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6068 <dd><a
6069 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6070 feature registry.</cite></a> Microsoft. URL: <a
6071 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6072 </dd>
6073 <!---->
6075 <dt id=RFC2119>[RFC2119]
6077 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6078 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6079 RFC 2119. URL: <a
6080 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6081 </dd>
6082 <!---->
6084 <dt id=UAX15>[UAX15]
6086 <dd>Mark Davis; Ken Whistler. <a
6087 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6088 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6089 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6090 </dd>
6091 <!---->
6093 <dt id=UAX29>[UAX29]
6095 <dd>Mark Davis. <a
6096 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6097 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6098 URL: <a
6099 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6100 </dd>
6101 <!---->
6103 <dt id=UNICODE6>[UNICODE6]
6105 <dd>The Unicode Consortium. <a
6106 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6107 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6108 Version 6.2.0 URL: <a
6109 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6110 </dd>
6111 <!---->
6112 </dl>
6113 <!--end-normative-->
6114 <!--{{!CSS21}}-->
6115 <!--{{!CSS3VAL}}-->
6116 <!--{{!OPENTYPE}}-->
6117 <!--{{!OPENTYPE-FEATURES}}-->
6118 <!--{{!OPEN-FONT-FORMAT}}-->
6119 <!--{{!UNICODE6}}-->
6120 <!--{{!UAX15}}-->
6121 <!--{{!UAX29}}-->
6122 <!--{{!CORS}}-->
6123 <!--{{!HTML5}}-->
6124 <!--{{!CHARMOD}}-->
6126 <h3 class=no-num id=other-references>Other References</h3>
6127 <!--begin-informative-->
6128 <!-- Sorted by label -->
6130 <dl class=bibliography>
6131 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6132 <!---->
6134 <dt id=AAT-FEATURES>[AAT-FEATURES]
6136 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6137 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6138 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6139 </dd>
6140 <!---->
6142 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6144 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6145 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6146 <!---->
6148 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6150 <dd>François Yergeau; et al. <a
6151 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6152 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6153 W3C Working Draft. (Work in progress.) URL: <a
6154 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6155 </dd>
6156 <!---->
6158 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6160 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6161 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6162 <!---->
6164 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6166 <dd>L. David Baron. <a
6167 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6168 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6169 Recommendation. (Work in progress.) URL: <a
6170 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6171 </dd>
6172 <!---->
6174 <dt id=CSS3TEXT>[CSS3TEXT]
6176 <dd>Elika J. Etemad; Koji Ishii. <a
6177 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6178 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6179 progress.) URL: <a
6180 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6181 </dd>
6182 <!---->
6184 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6186 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6187 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6188 ISBN 0-201-17633-5.</dd>
6189 <!---->
6191 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6193 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6194 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6195 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6196 2000. W3C Recommendation. URL: <a
6197 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>
6198 </dd>
6199 <!---->
6201 <dt id=ELEMTYPO>[ELEMTYPO]
6203 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6204 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6205 <!---->
6207 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6209 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6210 ISBN 1-932026-01-0.</dd>
6211 <!---->
6213 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6215 <dd><a
6216 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6217 User Guide.</cite></a> FontShop International. URL: <a
6218 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6219 </dd>
6220 <!---->
6222 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6224 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6225 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6226 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6227 <!---->
6229 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6231 <dd>John Hudson. <a
6232 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6233 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6234 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6235 </dd>
6236 <!---->
6237 </dl>
6238 <!--end-informative-->
6239 <!--{{ARABIC-TYPO}}-->
6240 <!--{{CJKV-INFO-PROCESSING}}-->
6241 <!--{{DIGITAL-TYPOGRAPHY}}-->
6242 <!--{{DOM-LEVEL-2-STYLE}}-->
6243 <!--{{ELEMTYPO}}-->
6244 <!--{{LANGCULTTYPE}}-->
6245 <!--{{OPENTYPE-FONT-GUIDE}}-->
6246 <!--{{RASTER-TRAGEDY}}-->
6247 <!--{{WINDOWS-GLYPH-PROC}}-->
6248 <!--{{CHARMOD-NORM}}-->
6249 <!--{{AAT-FEATURES}}-->
6250 <!--{{CSS3-CONDITIONAL}}-->
6251 <!--{{CSS3TEXT}}-->
6253 <h2 class=no-num id=index>Index</h2>
6254 <!--begin-index-->
6256 <ul class=indexlist>
6257 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6258 title="100...900 weight values"><strong>3.2</strong></a>
6260 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6261 title="<absolute-size>"><strong>3.5</strong></a>
6263 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6264 title="<common-lig-values>"><strong>6.4</strong></a>
6266 <li><var><contextual-alt-values></var>, <a
6267 href="#contextual-alt-values"
6268 title="<contextual-alt-values>"><strong>6.4</strong></a>
6270 <li><var><discretionary-lig-values></var>, <a
6271 href="#discretionary-lig-values"
6272 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6274 <li><var><east-asian-variant-values></var>, <a
6275 href="#east-asian-variant-values"
6276 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6278 <li><var><east-asian-width-values></var>, <a
6279 href="#east-asian-width-values"
6280 title="<east-asian-width-values>"><strong>6.10</strong></a>
6282 <li><var><family-name></var>, <a href="#family-name-value"
6283 title="<family-name>"><strong>3.1</strong></a>
6285 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6286 title="<feature-tag-value>"><strong>6.12</strong></a>
6288 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6289 title="<font-face-name>"><strong>4.3</strong></a>
6291 <li><var><font-variant-css21></var>, <a
6292 href="#font-variant-css21-values"
6293 title="<font-variant-css21>"><strong>3.7</strong></a>
6295 <li><var><generic-family></var>, <a href="#generic-family-value"
6296 title="<generic-family>"><strong>3.1</strong></a>
6298 <li><var><historical-lig-values></var>, <a
6299 href="#historical-lig-values"
6300 title="<historical-lig-values>"><strong>6.4</strong></a>
6302 <li><var><length></var>, <a href="#length-size-value"
6303 title="<length>"><strong>3.5</strong></a>
6305 <li><var><number></var>, <a href="#aspect-ratio-value"
6306 title="<number>"><strong>3.6</strong></a>
6308 <li><var><numeric-figure-values></var>, <a
6309 href="#numeric-figure-values"
6310 title="<numeric-figure-values>"><strong>6.7</strong></a>
6312 <li><var><numeric-fraction-values></var>, <a
6313 href="#numeric-fraction-values"
6314 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6316 <li><var><numeric-spacing-values></var>, <a
6317 href="#numeric-spacing-values"
6318 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6320 <li><var><percentage></var>, <a href="#percentage-size-value"
6321 title="<percentage>"><strong>3.5</strong></a>
6323 <li><var><relative-size></var>, <a href="#relative-size-value"
6324 title="<relative-size>"><strong>3.5</strong></a>
6326 <li><var><string></var>, <a
6327 href="#font-language-override-string-value"
6328 title="<string>"><strong>6.13</strong></a>
6330 <li><var><urange></var>, <a href="#urange-value"
6331 title="<urange>"><strong>4.5</strong></a>
6333 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6334 title="@font-face"><strong>4.1</strong></a>
6336 <li><code>@font-feature-values</code>, <a
6337 href="#at-font-feature-values-rule"
6338 title="@font-feature-values"><strong>6.9</strong></a>
6340 <li>all-petite-caps, <a href="#all-petite-caps"
6341 title=all-petite-caps><strong>6.6</strong></a>
6343 <li>all-small-caps, <a href="#all-small-caps"
6344 title=all-small-caps><strong>6.6</strong></a>
6346 <li>annotation, <a href="#annotation"
6347 title=annotation><strong>6.8</strong></a>
6349 <li>aspect value, <a href="#aspect-value0" title="aspect
6350 value"><strong>3.6</strong></a>
6352 <li>authoring tool, <a href="#authoring-tool" title="authoring
6353 tool"><strong>#</strong></a>
6355 <li>auto
6356 <ul>
6357 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6358 font-kerning"><strong>6.3</strong></a>
6360 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6361 title="auto, font-size-adjust"><strong>3.6</strong></a>
6362 </ul>
6364 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6366 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6368 <li>character map, <a href="#character-map" title="character
6369 map"><strong>5.2</strong></a>
6371 <li>character-variant, <a href="#character-variant"
6372 title=character-variant><strong>6.8</strong></a>
6374 <li>common-ligatures, <a href="#common-ligatures"
6375 title=common-ligatures><strong>6.4</strong></a>
6377 <li>condensed, <a href="#condensed"
6378 title=condensed><strong>3.3</strong></a>
6380 <li>contextual, <a href="#contextual"
6381 title=contextual><strong>6.4</strong></a>
6383 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6384 title=CSSFontFaceRule><strong>8.1</strong></a>
6386 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6387 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6389 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6390 of"><strong>#</strong></a>
6392 <li>default face, <a href="#default-face" title="default
6393 face"><strong>5.2</strong></a>
6395 <li>descriptor_declaration, <a href="#descriptordeclaration"
6396 title="descriptor_declaration"><strong>4.1</strong></a>
6398 <li>diagonal-fractions, <a href="#diagonal-fractions"
6399 title=diagonal-fractions><strong>6.7</strong></a>
6401 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6402 title=discretionary-ligatures><strong>6.4</strong></a>
6404 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6406 <li>extra-condensed, <a href="#extra-condensed"
6407 title=extra-condensed><strong>3.3</strong></a>
6409 <li>extra-expanded, <a href="#extra-expanded"
6410 title=extra-expanded><strong>3.3</strong></a>
6412 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6413 of"><strong>#</strong></a>
6415 <li>feature_type, <a href="#featuretype"
6416 title="feature_type"><strong>6.9.1</strong></a>
6418 <li>feature_value_block, <a href="#featurevalueblock"
6419 title="feature_value_block"><strong>6.9.1</strong></a>
6421 <li>feature_value_definition, <a href="#featurevaluedefinition"
6422 title="feature_value_definition"><strong>6.9.1</strong></a>
6424 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6426 <li>font specific, <a href="#font-specific" title="font
6427 specific"><strong>6.8</strong></a>
6429 <li>font-family
6430 <ul>
6431 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6432 descriptor"><strong>4.2</strong></a>
6434 <li>property, <a href="#propdef-font-family" title="font-family,
6435 property"><strong>3.1</strong></a>
6436 </ul>
6438 <li>font-feature-settings
6439 <ul>
6440 <li>descriptor, <a href="#descdef-font-feature-settings"
6441 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6443 <li>property, <a href="#propdef-font-feature-settings"
6444 title="font-feature-settings, property"><strong>6.12</strong></a>
6445 </ul>
6447 <li>font-kerning, <a href="#propdef-font-kerning"
6448 title=font-kerning><strong>6.3</strong></a>
6450 <li>font-language-override, <a href="#propdef-font-language-override"
6451 title=font-language-override><strong>6.13</strong></a>
6453 <li>font-size, <a href="#propdef-font-size"
6454 title=font-size><strong>3.5</strong></a>
6456 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6457 title=font-size-adjust><strong>3.6</strong></a>
6459 <li>font-stretch
6460 <ul>
6461 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6462 descriptor"><strong>4.4</strong></a>
6464 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6465 property"><strong>3.3</strong></a>
6466 </ul>
6468 <li>font-style
6469 <ul>
6470 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6471 descriptor"><strong>4.4</strong></a>
6473 <li>property, <a href="#propdef-font-style" title="font-style,
6474 property"><strong>3.4</strong></a>
6475 </ul>
6477 <li>font-synthesis, <a href="#propdef-font-synthesis"
6478 title=font-synthesis><strong>3.8</strong></a>
6480 <li>font-variant
6481 <ul>
6482 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6483 descriptor"><strong>4.7</strong></a>
6485 <li>property, <a href="#propdef-font-variant" title="font-variant,
6486 property"><strong>6.11</strong></a>
6487 </ul>
6489 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6490 title=font-variant-alternates><strong>6.8</strong></a>
6492 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6493 title=font-variant-caps><strong>6.6</strong></a>
6495 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6496 title=font-variant-east-asian><strong>6.10</strong></a>
6498 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6499 title=font-variant-ligatures><strong>6.4</strong></a>
6501 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6502 title=font-variant-numeric><strong>6.7</strong></a>
6504 <li>font-variant-position, <a href="#propdef-font-variant-position"
6505 title=font-variant-position><strong>6.5</strong></a>
6507 <li>font-weight
6508 <ul>
6509 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6510 descriptor"><strong>4.4</strong></a>
6512 <li>property, <a href="#propdef-font-weight" title="font-weight,
6513 property"><strong>3.2</strong></a>
6514 </ul>
6516 <li>font_face_rule, <a href="#fontfacerule"
6517 title="font_face_rule"><strong>4.1</strong></a>
6519 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6520 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6522 <li>font_family_name, <a href="#fontfamilyname"
6523 title="font_family_name"><strong>6.9.1</strong></a>
6525 <li>font_family_name_list, <a href="#fontfamilynamelist"
6526 title="font_family_name_list"><strong>6.9.1</strong></a>
6528 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6529 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6531 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6532 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6534 <li>full-width, <a href="#full-width"
6535 title=full-width><strong>6.10</strong></a>
6537 <li>historical-forms, <a href="#historical-forms"
6538 title=historical-forms><strong>6.8</strong></a>
6540 <li>historical-ligatures, <a href="#historical-ligatures"
6541 title=historical-ligatures><strong>6.4</strong></a>
6543 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6545 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6547 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6549 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6551 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6553 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6555 <li>lining-nums, <a href="#lining-nums"
6556 title=lining-nums><strong>6.7</strong></a>
6558 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6559 definition of"><strong>#</strong></a>
6561 <li>no-common-ligatures, <a href="#no-common-ligatures"
6562 title=no-common-ligatures><strong>6.4</strong></a>
6564 <li>no-contextual, <a href="#no-contextual"
6565 title=no-contextual><strong>6.4</strong></a>
6567 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6568 title=no-discretionary-ligatures><strong>6.4</strong></a>
6570 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6571 title=no-historical-ligatures><strong>6.4</strong></a>
6573 <li>none
6574 <ul>
6575 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6576 font-kerning"><strong>6.3</strong></a>
6578 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6579 title="none, font-size-adjust"><strong>3.6</strong></a>
6581 <li>font-variant, <a href="#font-variant-none-value" title="none,
6582 font-variant"><strong>6.11</strong></a>
6584 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6585 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6586 </ul>
6588 <li>normal
6589 <ul>
6590 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6591 title="normal, font-feature-settings"><strong>6.12</strong></a>
6593 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6594 font-kerning"><strong>6.3</strong></a>
6596 <li>font-language-override, <a
6597 href="#font-language-override-normal-value" title="normal,
6598 font-language-override"><strong>6.13</strong></a>
6600 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6601 font-stretch"><strong>3.3</strong></a>
6603 <li>font-style, <a href="#font-style-normal-value" title="normal,
6604 font-style"><strong>3.4</strong></a>
6606 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6607 font-variant"><strong>6.11</strong></a>
6609 <li>font-variant-alternates, <a
6610 href="#font-variant-alternates-normal-value" title="normal,
6611 font-variant-alternates"><strong>6.8</strong></a>
6613 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6614 title="normal, font-variant-caps"><strong>6.6</strong></a>
6616 <li>font-variant-east-asian, <a
6617 href="#font-variant-east-asian-normal-value" title="normal,
6618 font-variant-east-asian"><strong>6.10</strong></a>
6620 <li>font-variant-ligatures, <a
6621 href="#font-variant-ligatures-normal-value" title="normal,
6622 font-variant-ligatures"><strong>6.4</strong></a>
6624 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6625 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6627 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6628 title="normal, font-variant-position"><strong>6.5</strong></a>
6630 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6631 font-weight"><strong>3.2</strong></a>
6632 </ul>
6634 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6636 <li>oldstyle-nums, <a href="#oldstyle-nums"
6637 title=oldstyle-nums><strong>6.7</strong></a>
6639 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6641 <li>ornaments, <a href="#ornaments"
6642 title=ornaments><strong>6.8</strong></a>
6644 <li>petite-caps, <a href="#petite-caps"
6645 title=petite-caps><strong>6.6</strong></a>
6647 <li>proportional-nums, <a href="#proportional-nums"
6648 title=proportional-nums><strong>6.7</strong></a>
6650 <li>proportional-width, <a href="#proportional-width"
6651 title=proportional-width><strong>6.10</strong></a>
6653 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6655 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6657 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6658 definition of"><strong>#</strong></a>
6660 <li>semi-condensed, <a href="#semi-condensed-"
6661 title=semi-condensed><strong>3.3</strong></a>
6663 <li>semi-expanded, <a href="#semi-expanded"
6664 title=semi-expanded><strong>3.3</strong></a>
6666 <li>serif, definition of, <a href="#serif0" title="serif, definition
6667 of"><strong>#</strong></a>
6669 <li>simplified, <a href="#simplified"
6670 title=simplified><strong>6.10</strong></a>
6672 <li>slashed-zero, <a href="#slashed-zero"
6673 title=slashed-zero><strong>6.7</strong></a>
6675 <li>small-caps, <a href="#small-caps"
6676 title=small-caps><strong>6.6</strong></a>
6678 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6680 <li>stacked-fractions, <a href="#stacked-fractions"
6681 title=stacked-fractions><strong>6.7</strong></a>
6683 <li>style sheet
6684 <ul>
6685 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6686 conformance class"><strong>#</strong></a>
6687 </ul>
6689 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6691 <li>stylistic, <a href="#stylistic"
6692 title=stylistic><strong>6.8</strong></a>
6694 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6696 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6698 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6700 <li>system font fallback, <a href="#system-font-fallback" title="system
6701 font fallback"><strong>5.2</strong></a>
6703 <li>tabular-nums, <a href="#tabular-nums"
6704 title=tabular-nums><strong>6.7</strong></a>
6706 <li>titling-caps, <a href="#titling-caps"
6707 title=titling-caps><strong>6.6</strong></a>
6709 <li>traditional, <a href="#traditional"
6710 title=traditional><strong>6.10</strong></a>
6712 <li>ultra-condensed, <a href="#ultra-condensed"
6713 title=ultra-condensed><strong>3.3</strong></a>
6715 <li>ultra-expanded, <a href="#ultra-expanded"
6716 title=ultra-expanded><strong>3.3</strong></a>
6718 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6720 <li>unicode-range, <a href="#descdef-unicode-range"
6721 title=unicode-range><strong>4.5</strong></a>
6723 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6725 <li>width, <a href="#width" title=width><strong>2</strong></a>
6726 </ul>
6727 <!--end-index-->
6729 <h2 class=no-num id=property-index>Property index</h2>
6730 <!--begin-properties-->
6732 <table class=proptable>
6733 <thead>
6734 <tr>
6735 <th>Property
6737 <th>Values
6739 <th>Initial
6741 <th>Applies to
6743 <th>Inh.
6745 <th>Percentages
6747 <th>Media
6749 <tbody>
6750 <tr>
6751 <th><a class=property href="#propdef-font">font</a>
6753 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6754 <‘font-weight’> || <‘font-stretch’ ]?
6755 <‘font-size’> [ / <‘line-height’> ]?
6756 <‘font-family’> ] | caption | icon | menu | message-box |
6757 small-caption | status-bar
6759 <td>see individual properties
6761 <td>all elements
6763 <td>yes
6765 <td>see individual properties
6767 <td>visual
6769 <tr>
6770 <th><span class=property>font-family</span>
6772 <td>[ <family-name> | <generic-family> ] #
6774 <td>depends on user agent
6776 <td>all elements
6778 <td>yes
6780 <td>N/A
6782 <td>visual
6784 <tr>
6785 <th><span class=property>font-feature-settings</span>
6787 <td>normal | <feature-tag-value> #
6789 <td>normal
6791 <td>all elements
6793 <td>yes
6795 <td>N/A
6797 <td>visual
6799 <tr>
6800 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6802 <td>auto | normal | none
6804 <td>auto
6806 <td>all elements
6808 <td>yes
6810 <td>N/A
6812 <td>visual
6814 <tr>
6815 <th><a class=property
6816 href="#propdef-font-language-override">font-language-override</a>
6818 <td>normal | <string>
6820 <td>normal
6822 <td>all elements
6824 <td>yes
6826 <td>N/A
6828 <td>visual
6830 <tr>
6831 <th><a class=property href="#propdef-font-size">font-size</a>
6833 <td><absolute-size> | <relative-size> | <length> |
6834 <percentage>
6836 <td>medium
6838 <td>all elements
6840 <td>yes
6842 <td>refer to parent element's font size
6844 <td>visual
6846 <tr>
6847 <th><a class=property
6848 href="#propdef-font-size-adjust">font-size-adjust</a>
6850 <td>none | auto | <number>
6852 <td>none
6854 <td>all elements
6856 <td>yes
6858 <td>N/A
6860 <td>visual
6862 <tr>
6863 <th><span class=property>font-stretch</span>
6865 <td>normal | ultra-condensed | extra-condensed | condensed |
6866 semi-condensed | semi-expanded | expanded | extra-expanded |
6867 ultra-expanded
6869 <td>normal
6871 <td>all elements
6873 <td>yes
6875 <td>N/A
6877 <td>visual
6879 <tr>
6880 <th><span class=property>font-style</span>
6882 <td>normal | italic | oblique
6884 <td>normal
6886 <td>all elements
6888 <td>yes
6890 <td>N/A
6892 <td>visual
6894 <tr>
6895 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6897 <td>none | [ weight || style ]
6899 <td>weight style
6901 <td>all elements
6903 <td>yes
6905 <td>N/A
6907 <td>visual
6909 <tr>
6910 <th><span class=property>font-variant</span>
6912 <td>normal | none | [ <common-lig-values> ||
6913 <discretionary-lig-values> || <historical-lig-values> ||
6914 <contextual-alt-values> || stylistic(<feature-value-name>)
6915 || historical-forms || styleset(<feature-value-name> #) ||
6916 character-variant(<feature-value-name> #) ||
6917 swash(<feature-value-name>) ||
6918 ornaments(<feature-value-name>) ||
6919 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6920 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6921 <numeric-figure-values> || <numeric-spacing-values> ||
6922 <numeric-fraction-values> || ordinal || slashed-zero ||
6923 <east-asian-variant-values> || <east-asian-width-values> ||
6924 ruby ]
6926 <td>normal
6928 <td>all elements
6930 <td>yes
6932 <td>see individual properties
6934 <td>visual
6936 <tr>
6937 <th><a class=property
6938 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6940 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6941 || styleset(<feature-value-name> #) ||
6942 character-variant(<feature-value-name> #) ||
6943 swash(<feature-value-name>) ||
6944 ornaments(<feature-value-name>) ||
6945 annotation(<feature-value-name>) ]
6947 <td>normal
6949 <td>all elements
6951 <td>yes
6953 <td>N/A
6955 <td>visual
6957 <tr>
6958 <th><a class=property
6959 href="#propdef-font-variant-caps">font-variant-caps</a>
6961 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
6962 | unicase | titling-caps
6964 <td>normal
6966 <td>all elements
6968 <td>yes
6970 <td>N/A
6972 <td>visual
6974 <tr>
6975 <th><a class=property
6976 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
6978 <td>normal | [ <east-asian-variant-values> ||
6979 <east-asian-width-values> || ruby ]
6981 <td>normal
6983 <td>all elements
6985 <td>yes
6987 <td>N/A
6989 <td>visual
6991 <tr>
6992 <th><a class=property
6993 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
6995 <td>normal | none | [ <common-lig-values> ||
6996 <discretionary-lig-values> || <historical-lig-values> ||
6997 <contextual-alt-values> ]
6999 <td>normal
7001 <td>all elements
7003 <td>yes
7005 <td>N/A
7007 <td>visual
7009 <tr>
7010 <th><a class=property
7011 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7013 <td>normal | [ <numeric-figure-values> ||
7014 <numeric-spacing-values> || <numeric-fraction-values> ||
7015 ordinal || slashed-zero ]
7017 <td>normal
7019 <td>all elements
7021 <td>yes
7023 <td>N/A
7025 <td>visual
7027 <tr>
7028 <th><a class=property
7029 href="#propdef-font-variant-position">font-variant-position</a>
7031 <td>normal | sub | super
7033 <td>normal
7035 <td>all elements
7037 <td>yes
7039 <td>N/A
7041 <td>visual
7043 <tr>
7044 <th><span class=property>font-weight</span>
7046 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7047 | 700 | 800 | 900
7049 <td>normal
7051 <td>all elements
7053 <td>yes
7055 <td>N/A
7057 <td>visual
7058 </table>
7059 <!--end-properties-->
7060 <!--begin-descriptors-->
7062 <table class=proptable>
7063 <thead>
7064 <tr>
7065 <th>Descriptor
7067 <th>Value
7069 <th>Initial
7071 <th>Percentages
7073 <th>Media
7075 <tbody>
7076 <tr>
7077 <th><span class=property>font-family</span>
7079 <td><family-name>
7081 <td>N/A
7083 <tr>
7084 <th><span class=property>font-feature-settings</span>
7086 <td>normal | <feature-tag-value> #
7088 <td>normal
7090 <tr>
7091 <th><span class=property>font-stretch</span>
7093 <td>normal | ultra-condensed | extra-condensed | condensed |
7094 semi-condensed | semi-expanded | expanded | extra-expanded |
7095 ultra-expanded
7097 <td>normal
7099 <tr>
7100 <th><span class=property>font-style</span>
7102 <td>normal | italic | oblique
7104 <td>normal
7106 <tr>
7107 <th><span class=property>font-variant</span>
7109 <td>normal | none | [ <common-lig-values> ||
7110 <discretionary-lig-values> || <historical-lig-values> ||
7111 <contextual-alt-values> || stylistic(<feature-value-name>)
7112 || historical-forms || styleset(<feature-value-name> #) ||
7113 character-variant(<feature-value-name> #) ||
7114 swash(<feature-value-name>) ||
7115 ornaments(<feature-value-name>) ||
7116 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7117 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7118 <numeric-figure-values> || <numeric-spacing-values> ||
7119 <numeric-fraction-values> || ordinal || slashed-zero ||
7120 <east-asian-variant-values> || <east-asian-width-values> ||
7121 ruby ]
7123 <td>normal
7125 <tr>
7126 <th><span class=property>font-weight</span>
7128 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7130 <td>normal
7132 <tr>
7133 <th><a class=property href="#descdef-src">src</a>
7135 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7137 <td>N/A
7139 <tr>
7140 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7142 <td><urange> #
7144 <td>U+0-10FFFF
7145 </table>
7146 <!--end-descriptors-->
7147 <script type="text/javascript">
7148 window.onload = function () {
7149 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7150 var i, hiresElements = document.getElementsByClassName("hires");
7151 for (i = 0; i < hiresElements.length; i++) {
7152 var h = hiresElements[i];
7153 if (h.tagName != "IMG") continue;
7154 var src = h.getAttribute("src");
7155 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7156 h.src = src2x;
7157 }
7158 }
7159 </script>
7160 </html>
7161 <!-- Keep this comment at the end of the file
7162 Local variables:
7163 mode: sgml
7164 sgml-declaration:"~/SGML/HTML4.decl"
7165 sgml-default-doctype-name:"html"
7166 sgml-minimize-attributes:t
7167 sgml-nofill-elements:("pre" "style" "br")
7168 sgml-live-element-indicator:t
7169 sgml-omittag:nil
7170 sgml-shorttag:nil
7171 sgml-namecase-general:t
7172 sgml-general-insert-case:lower
7173 sgml-always-quote-attributes:t
7174 sgml-indent-step:nil
7175 sgml-indent-data:t
7176 sgml-parent-document:nil
7177 sgml-exposed-tags:nil
7178 sgml-local-catalogs:nil
7179 sgml-local-ecat-files:nil
7180 End:
7181 -->
7182 <!--
7184 to do:
7186 - wording of OpenType family name handling
7187 - handling combining sequences in the font matching algorithm
7188 - fix-up fi ligature example
7190 -->
