-
Notifications
You must be signed in to change notification settings - Fork 790
Expand file tree
/
Copy pathOverview.html
More file actions
executable file
·3451 lines (2590 loc) · 125 KB
/
Overview.html
File metadata and controls
executable file
·3451 lines (2590 loc) · 125 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang=en>
<head profile="http://dublincore.org/documents/2008/08/04/dc-html/ ">
<title>Selectors Level 3</title>
<link href="http://purl.org/dc/terms/" rel=schema.dcterms>
<link href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=dcterms.rights>
<meta content="Selectors Level 3" name=dcterms.title>
<meta content=text name=dcterms.type>
<meta content=2013-01-02 name=dcterms.issued>
<meta content="" name=dcterms.creator>
<meta content=W3C name=dcterms.publisher>
<meta content="http://www.w3.org/TR/2013/ED-selectors3-20130102/"
name=dcterms.identifier>
<link href="../default.css" rel=stylesheet type="text/css">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
type="text/css">
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 id=title>Selectors Level 3</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 2 January 2013</h2>
<dl>
<dt>This version:
<dd> <!-- <a href="http://www.w3.org/TR/2013/ED-selectors3-20130102/">
http://www.w3.org/TR/2013/REC-selectors3-20130102</a> -->
<a href="http://dev.w3.org/csswg/selectors3">
http://dev.w3.org/csswg/selectors3</a>
<dt>Latest version:
<dd><a href="http://www.w3.org/TR/css3-selectors">
http://www.w3.org/TR/css3-selectors</a>
<dt>Previous version:
<dd><a href="http://www.w3.org/TR/2009/PR-css3-selectors-20091215/">
http://www.w3.org/TR/2009/PR-css3-selectors-20091215/</a>
<dt><a name=editors-list></a>Editors:
<dd class=vcard><a class="url fn" href="http://www.tantek.com/"
lang=tr>Tantek Çelik</a> (Invited Expert)
<dd class=vcard><a class="url fn"
href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>
(Invited Expert)
<dd class=vcard><span class=fn>Daniel Glazman</span> (Disruptive
Innovations SARL)
<dd class=vcard><a class="url fn" href="mailto:ian@hixie.ch">Ian
Hickson</a> (<span class=company><a
href="http://www.google.com/">Google</a></span>)
<dd class=vcard><span class=fn>Peter Linss</span> (former editor, <span
class=company><a
href="http://www.netscape.com/">Netscape/AOL</a></span>)
<dd class=vcard><span class=fn>John Williams</span> (former editor, <span
class=company><a href="http://www.quark.com/">Quark, Inc.</a></span>)
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><abbr
title="Massachusetts Institute of Technology">MIT</abbr></a>, <a
href="http://www.ercim.eu/"><abbr
title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
<a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p><a href="#selector"><em>Selectors</em></a> are patterns that match
against elements in a tree, and as such form one of several technologies
that can be used to select nodes in an XML document. Selectors have been
optimized for use with HTML and XML, and are designed to be usable in
performance-critical code.
<p><acronym title="Cascading Style Sheets">CSS</acronym> (Cascading Style
Sheets) is a language for describing the rendering of <acronym
title="Hypertext Markup Language">HTML</acronym> and <acronym
title="Extensible Markup Language">XML</acronym> documents on screen, on
paper, in speech, etc. CSS uses Selectors for binding style properties to
elements in the document.
<p>This document describes the selectors that already exist in <abbr
title="CSS level 1">CSS1</abbr> <a href="#CSS1"
rel=biblioentry>[CSS1]<!--{{CSS1}}--></a> and <abbr
title="CSS level 2">CSS2</abbr> <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>, and further introduces new
selectors for <abbr title="CSS level 3">CSS3</abbr> and other languages
that may need them.
<p>Selectors define the following function:
<pre>expression ∗ element → boolean</pre>
<p>That is, given an element and a selector, this specification defines
whether that element matches the selector.
<p>These expressions can also be used, for instance, to select a set of
elements, or a single element from a set of elements, by evaluating the
expression across all the elements in a subtree. <acronym
title="Simple Tree Transformation Sheets">STTS</acronym> (Simple Tree
Transformation Sheets), a language for transforming XML trees, uses this
mechanism. <a href="#STTS3" rel=biblioentry>[STTS3]<!--{{STTS3}}--></a>
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<!--begin-status-->
<p>This is a public copy of the editors' draft. It is provided for
discussion only and may change at any moment. Its publication here does
not imply endorsement of its contents by W3C. Don't cite this document
other than as work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org?Subject=%5Bselectors3%5D%20PUT%20SUBJECT%20HERE">
www-style@w3.org</a> (see <a
href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
discussion of this specification. When sending e-mail, please put the text
“selectors3” in the subject, preferably like this:
“[selectors3] <em>…summary of comment…</em>”
<p>This document was produced by the <a href="/Style/CSS/members">CSS
Working Group</a> (part of the <a href="/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent
Policy</a>. W3C maintains a <a href="/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the
W3C Patent Policy</a>.</p>
<!--end-status-->
<p>A separate <a
href="/Style/CSS/Test/CSS3/Selectors/20091025/reports/CR-ImpReport.html">
implementation report</a> contains a test suite and shows several
implementations of the specification.
<h2 class="no-num no-toc" id=contents>Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#context"><span class=secno>1. </span>Introduction</a>
<ul class=toc>
<li><a href="#dependencies"><span class=secno>1.1.
</span>Dependencies</a>
<li><a href="#terminology"><span class=secno>1.2. </span>Terminology</a>
<li><a href="#changesFromCSS2"><span class=secno>1.3. </span>Changes
from CSS2</a>
</ul>
<li><a href="#selectors"><span class=secno>2. </span>Selectors</a>
<li><a href="#casesens"><span class=secno>3. </span>Case sensitivity</a>
<li><a href="#selector-syntax"><span class=secno>4. </span>Selector
syntax</a>
<li><a href="#grouping"><span class=secno>5. </span>Groups of
selectors</a>
<li><a href="#simple-selectors"><span class=secno>6. </span>Simple
selectors</a>
<ul class=toc>
<li><a href="#type-selectors"><span class=secno>6.1. </span>Type
selector</a>
<ul class=toc>
<li><a href="#typenmsp"><span class=secno>6.1.1. </span>Type selectors
and namespaces</a>
</ul>
<li><a href="#universal-selector"><span class=secno>6.2.
</span>Universal selector </a>
<ul class=toc>
<li><a href="#univnmsp"><span class=secno>6.2.1. </span>Universal
selector and namespaces</a>
</ul>
<li><a href="#attribute-selectors"><span class=secno>6.3.
</span>Attribute selectors</a>
<ul class=toc>
<li><a href="#attribute-representation"><span class=secno>6.3.1.
</span>Attribute presence and value selectors</a>
<li><a href="#attribute-substrings"><span class=secno>6.3.2.
</span>Substring matching attribute selectors</a>
<li><a href="#attrnmsp"><span class=secno>6.3.3. </span>Attribute
selectors and namespaces</a>
<li><a href="#def-values"><span class=secno>6.3.4. </span>Default
attribute values in DTDs</a>
</ul>
<li><a href="#class-html"><span class=secno>6.4. </span>Class
selectors</a>
<li><a href="#id-selectors"><span class=secno>6.5. </span>ID
selectors</a>
<li><a href="#pseudo-classes"><span class=secno>6.6.
</span>Pseudo-classes</a>
<ul class=toc>
<li><a href="#dynamic-pseudos"><span class=secno>6.6.1. </span>Dynamic
pseudo-classes</a>
<ul class=toc>
<li><a href="#the-link-pseudo-classes-link-and-visited"><span
class=secno>6.6.1.1. </span>The link pseudo-classes: :link and
:visited</a>
<li><a href="#the-user-action-pseudo-classes-hover-act"><span
class=secno>6.6.1.2. </span>The user action pseudo-classes :hover,
:active, and :focus</a>
</ul>
<li><a href="#target-pseudo"><span class=secno>6.6.2. </span>The
target pseudo-class :target</a>
<li><a href="#lang-pseudo"><span class=secno>6.6.3. </span>The
language pseudo-class :lang</a>
<li><a href="#UIstates"><span class=secno>6.6.4. </span>The UI element
states pseudo-classes</a>
<ul class=toc>
<li><a href="#enableddisabled"><span class=secno>6.6.4.1. </span>The
:enabled and :disabled pseudo-classes</a>
<li><a href="#checked"><span class=secno>6.6.4.2. </span>The
:checked pseudo-class</a>
<li><a href="#indeterminate"><span class=secno>6.6.4.3. </span>The
:indeterminate pseudo-class</a>
</ul>
<li><a href="#structural-pseudos"><span class=secno>6.6.5.
</span>Structural pseudo-classes</a>
<ul class=toc>
<li><a href="#root-pseudo"><span class=secno>6.6.5.1. </span>:root
pseudo-class</a>
<li><a href="#nth-child-pseudo"><span class=secno>6.6.5.2.
</span>:nth-child() pseudo-class</a>
<li><a href="#nth-last-child-pseudo"><span class=secno>6.6.5.3.
</span>:nth-last-child() pseudo-class</a>
<li><a href="#nth-of-type-pseudo"><span class=secno>6.6.5.4.
</span>:nth-of-type() pseudo-class</a>
<li><a href="#nth-last-of-type-pseudo"><span class=secno>6.6.5.5.
</span>:nth-last-of-type() pseudo-class</a>
<li><a href="#first-child-pseudo"><span class=secno>6.6.5.6.
</span>:first-child pseudo-class</a>
<li><a href="#last-child-pseudo"><span class=secno>6.6.5.7.
</span>:last-child pseudo-class</a>
<li><a href="#first-of-type-pseudo"><span class=secno>6.6.5.8.
</span>:first-of-type pseudo-class</a>
<li><a href="#last-of-type-pseudo"><span class=secno>6.6.5.9.
</span>:last-of-type pseudo-class</a>
<li><a href="#only-child-pseudo"><span class=secno>6.6.5.10.
</span>:only-child pseudo-class</a>
<li><a href="#only-of-type-pseudo"><span class=secno>6.6.5.11.
</span>:only-of-type pseudo-class</a>
<li><a href="#empty-pseudo"><span class=secno>6.6.5.12.
</span>:empty pseudo-class</a>
</ul>
<li><a href="#content-selectors"><span class=secno>6.6.6.
</span>Blank</a>
<li><a href="#negation"><span class=secno>6.6.7. </span>The negation
pseudo-class</a>
</ul>
</ul>
<li><a href="#pseudo-elements"><span class=secno>7.
</span>Pseudo-elements</a>
<ul class=toc>
<li><a href="#first-line"><span class=secno>7.1. </span>The ::first-line
pseudo-element</a>
<ul class=toc>
<li><a href="#first-formatted-line"><span class=secno>7.1.1.
</span>First formatted line definition in CSS</a>
</ul>
<li><a href="#first-letter"><span class=secno>7.2. </span>The
::first-letter pseudo-element</a>
<ul class=toc>
<li><a href="#application-in-css"><span class=secno>7.2.1.
</span>Application in CSS</a>
</ul>
<li><a href="#selection"><span class=secno>7.3. </span>Blank</a>
<li><a href="#gen-content"><span class=secno>7.4. </span>The ::before
and ::after pseudo-elements</a>
</ul>
<li><a href="#combinators"><span class=secno>8. </span>Combinators</a>
<ul class=toc>
<li><a href="#descendant-combinators"><span class=secno>8.1.
</span>Descendant combinator</a>
<li><a href="#child-combinators"><span class=secno>8.2. </span>Child
combinators</a>
<li><a href="#sibling-combinators"><span class=secno>8.3. </span>Sibling
combinators</a>
<ul class=toc>
<li><a href="#adjacent-sibling-combinators"><span class=secno>8.3.1.
</span>Next-sibling combinator</a>
<li><a href="#general-sibling-combinators"><span class=secno>8.3.2.
</span>Following-sibling combinator</a>
</ul>
</ul>
<li><a href="#specificity"><span class=secno>9. </span>Calculating a
selector's specificity</a>
<li><a href="#w3cselgrammar"><span class=secno>10. </span>The grammar of
Selectors</a>
<ul class=toc>
<li><a href="#grammar"><span class=secno>10.1. </span>Grammar</a>
<li><a href="#lex"><span class=secno>10.2. </span>Lexical scanner</a>
</ul>
<li><a href="#profiling"><span class=secno>11. </span>Profiles</a>
<li><a href="#Conformance"><span class=secno>12. </span>Conformance and
requirements</a>
<li><a href="#Tests"><span class=secno>13. </span>Tests</a>
<li><a href="#ACKS"><span class=secno>14. </span>Acknowledgements</a>
<li><a href="#references"><span class=secno>15. </span>References</a>
<ul class=toc>
<li><a href="#normative-references"><span class=secno>15.1.
</span>Normative References</a>
<li><a href="#informative-references"><span class=secno>15.2.
</span>Informative References</a>
</ul>
</ul>
<!--end-toc-->
<h2 id=context><span class=secno>1. </span>Introduction</h2>
<p>Selectors Level 1 and Selectors Level 2 are defined as the subsets of
selector functionality defined in the <a
href="http://www.w3.org/TR/REC-CSS1">CSS1</a> and <a
href="http://www.w3.org/TR/CSS21/">CSS2.1</a> specifications,
respectively.
<h3 id=dependencies><span class=secno>1.1. </span>Dependencies</h3>
<p>Some features of this specification are specific to CSS, or have
particular limitations or rules specific to CSS. In this specification,
these have been described in terms of CSS2.1. <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<h3 id=terminology><span class=secno>1.2. </span>Terminology</h3>
<p>All of the text of this specification is normative except examples,
notes, and sections explicitly marked as non-normative.
<p>Additional terminology is defined in the <a
href="http://www.w3.org/TR/CSS21/conform.html#defs">Definitions</a>
section of <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>.
Examples of document source code and fragments are given in XML <a
href="#XML10" rel=biblioentry>[XML10]<!--{{XML10}}--></a> or HTML <a
href="#HTML401" rel=biblioentry>[HTML401]<!--{{HTML401}}--></a> syntax.
<h3 id=changesFromCSS2><span class=secno>1.3. </span>Changes from CSS2</h3>
<p><em>This section is non-normative.</em>
<p>The main differences between the selectors in CSS2 and those in
Selectors are:
<ul>
<li>the list of basic definitions (selector, group of selectors, simple
selector, etc.) has been changed; in particular, what was referred to in
CSS2 as a simple selector is now called a sequence of simple selectors,
and the term "simple selector" is now used for the components of this
sequence
<li>an optional namespace component is now allowed in element type
selectors, the universal selector and attribute selectors
<li>a <a href="#general-sibling-combinators">new combinator</a> has been
introduced
<li>new simple selectors including substring matching attribute selectors,
and new pseudo-classes
<li>new pseudo-elements, and introduction of the "::" convention for
pseudo-elements
<li>the grammar has been rewritten
<li>profiles to be added to specifications integrating Selectors and
defining the set of selectors which is actually supported by each
specification
<li>Selectors are now a CSS3 Module and an independent specification;
other specifications can now refer to this document independently of CSS
<li>the specification now has its own test suite
</ul>
<h2 id=selectors><span class=secno>2. </span>Selectors</h2>
<p><em>This section is non-normative, as it merely summarizes the following
sections.</em>
<p>A Selector represents a structure. This structure can be used as a
condition (e.g. in a CSS rule) that determines which elements a selector
matches in the document tree, or as a flat description of the HTML or XML
fragment corresponding to that structure.
<p>Selectors may range from simple element names to rich contextual
representations.
<p>The following table summarizes the Selector syntax:
<table class=selectorsReview>
<thead>
<tr>
<th class=pattern>Pattern
<th class=meaning>Represents
<th class=described>Description
<th class=origin>Level
<tbody>
<tr>
<td class=pattern>*
<td class=meaning>any element
<td class=described><a href="#universal-selector">Universal selector</a>
<td class=origin>2
<tr>
<td class=pattern>E
<td class=meaning>an element of type E
<td class=described><a href="#type-selectors">Type selector</a>
<td class=origin>1
<tr>
<td class=pattern>E[foo]
<td class=meaning>an E element with a "foo" attribute
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E[foo="bar"]
<td class=meaning>an E element whose "foo" attribute value is exactly
equal to "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E[foo~="bar"]
<td class=meaning>an E element whose "foo" attribute value is a list of
whitespace-separated values, one of which is exactly equal to "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E[foo^="bar"]
<td class=meaning>an E element whose "foo" attribute value begins
exactly with the string "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>3
<tr>
<td class=pattern>E[foo$="bar"]
<td class=meaning>an E element whose "foo" attribute value ends exactly
with the string "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>3
<tr>
<td class=pattern>E[foo*="bar"]
<td class=meaning>an E element whose "foo" attribute value contains the
substring "bar"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>3
<tr>
<td class=pattern>E[foo|="en"]
<td class=meaning>an E element whose "foo" attribute has a
hyphen-separated list of values beginning (from the left) with "en"
<td class=described><a href="#attribute-selectors">Attribute
selectors</a>
<td class=origin>2
<tr>
<td class=pattern>E:root
<td class=meaning>an E element, root of the document
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-child(n)
<td class=meaning>an E element, the n-th child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-last-child(n)
<td class=meaning>an E element, the n-th child of its parent, counting
from the last one
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-of-type(n)
<td class=meaning>an E element, the n-th sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:nth-last-of-type(n)
<td class=meaning>an E element, the n-th sibling of its type, counting
from the last one
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:first-child
<td class=meaning>an E element, first child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>2
<tr>
<td class=pattern>E:last-child
<td class=meaning>an E element, last child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:first-of-type
<td class=meaning>an E element, first sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:last-of-type
<td class=meaning>an E element, last sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:only-child
<td class=meaning>an E element, only child of its parent
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:only-of-type
<td class=meaning>an E element, only sibling of its type
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:empty
<td class=meaning>an E element that has no children (including text
nodes)
<td class=described><a href="#structural-pseudos">Structural
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:link<br>
E:visited
<td class=meaning>an E element being the source anchor of a hyperlink of
which the target is not yet visited (:link) or already visited
(:visited)
<td class=described><a href="#link">The link pseudo-classes</a>
<td class=origin>1
<tr>
<td class=pattern>E:active<br>
E:hover<br>
E:focus
<td class=meaning>an E element during certain user actions
<td class=described><a href="#useraction-pseudos">The user action
pseudo-classes</a>
<td class=origin>1 and 2
<tr>
<td class=pattern>E:target
<td class=meaning>an E element being the target of the referring URI
<td class=described><a href="#target-pseudo">The target pseudo-class</a>
<td class=origin>3
<tr>
<td class=pattern>E:lang(fr)
<td class=meaning>an element of type E in language "fr" (the document
language specifies how language is determined)
<td class=described><a href="#lang-pseudo">The :lang() pseudo-class</a>
<td class=origin>2
<tr>
<td class=pattern>E:enabled<br>
E:disabled
<td class=meaning>a user interface element E which is enabled or
disabled
<td class=described><a href="#UIstates">The UI element states
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E:checked<!--<br>E:indeterminate-->
<td class=meaning>a user interface element E which is
checked<!-- or in an
indeterminate state--> (for instance a
radio-button or checkbox)
<td class=described><a href="#UIstates">The UI element states
pseudo-classes</a>
<td class=origin>3
<tr>
<td class=pattern>E::first-line
<td class=meaning>the first formatted line of an E element
<td class=described><a href="#first-line">The ::first-line
pseudo-element</a>
<td class=origin>1
<tr>
<td class=pattern>E::first-letter
<td class=meaning>the first formatted letter of an E element
<td class=described><a href="#first-letter">The ::first-letter
pseudo-element</a>
<td class=origin>1
<tr>
<td class=pattern>E::before
<td class=meaning>generated content before an E element
<td class=described><a href="#gen-content">The ::before
pseudo-element</a>
<td class=origin>2
<tr>
<td class=pattern>E::after
<td class=meaning>generated content after an E element
<td class=described><a href="#gen-content">The ::after
pseudo-element</a>
<td class=origin>2
<tr>
<td class=pattern>E.warning
<td class=meaning>an E element whose class is "warning" (the document
language specifies how class is determined).
<td class=described><a href="#class-html">Class selectors</a>
<td class=origin>1
<tr>
<td class=pattern>E#myid
<td class=meaning>an E element with ID equal to "myid".
<td class=described><a href="#id-selectors">ID selectors</a>
<td class=origin>1
<tr>
<td class=pattern>E:not(s)
<td class=meaning>an E element that does not match simple selector s
<td class=described><a href="#negation">Negation pseudo-class</a>
<td class=origin>3
<tr>
<td class=pattern>E F
<td class=meaning>an F element descendant of an E element
<td class=described><a href="#descendant-combinators">Descendant
combinator</a>
<td class=origin>1
<tr>
<td class=pattern>E > F
<td class=meaning>an F element child of an E element
<td class=described><a href="#child-combinators">Child combinator</a>
<td class=origin>2
<tr>
<td class=pattern>E + F
<td class=meaning>an F element immediately preceded by an E element
<td class=described><a href="#adjacent-sibling-combinators">Next-sibling
combinator</a>
<td class=origin>2
<tr>
<td class=pattern>E ~ F
<td class=meaning>an F element preceded by an E element
<td class=described><a
href="#general-sibling-combin
142A
ators">Following-sibling combinator</a>
<td class=origin>3
</table>
<h2 id=casesens><span class=secno>3. </span>Case sensitivity</h2>
<p>All Selectors syntax is case-insensitive within the ASCII range (i.e.
[a-z] and [A-Z] are equivalent), except for parts that are not under the
control of Selectors. The case sensitivity of document language element
names, attribute names, and attribute values in selectors depends on the
document language. For example, in HTML, element names are
case-insensitive, but in XML, they are case-sensitive. Case sensitivity of
namespace prefixes is defined in <a href="#CSS3NAMESPACE"
rel=biblioentry>[CSS3NAMESPACE]<!--{{!CSS3NAMESPACE}}--></a>.
<h2 id=selector-syntax><span class=secno>4. </span>Selector syntax</h2>
<p>A <dfn id=selector>selector</dfn> is a chain of one or more <a
href="#sequence">sequences of simple selectors</a> separated by <a
href="#combinators">combinators</a>. One <a
href="#pseudo-elements">pseudo-element</a> may be appended to the last
sequence of simple selectors in a selector.
<p>A <dfn id=sequence-of-simple-selectors><a name=sequence>sequence of
simple selectors</a></dfn> is a chain of <a
href="#simple-selectors-dfn">simple selectors</a> that are not separated
by a <a href="#combinators">combinator</a>. It always begins with a <a
href="#type-selectors">type selector</a> or a <a
href="#universal-selector">universal selector</a>. No other type selector
or universal selector is allowed in the sequence.
<p>A <dfn id=simple-selector><a name=simple-selectors-dfn></a><a
href="#simple-selectors">simple selector</a></dfn> is either a <a
href="#type-selectors">type selector</a>, <a
href="#universal-selector">universal selector</a>, <a
href="#attribute-selectors">attribute selector</a>, <a
href="#class-html">class selector</a>, <a href="#id-selectors">ID
selector</a>, or <a href="#pseudo-classes">pseudo-class</a>.
<p><dfn id=combinators0>Combinators</dfn> are: whitespace,
"greater-than sign" (U+003E, <code>></code>), "plus
sign" (U+002B, <code>+</code>) and "tilde" (U+007E,
<code>~</code>). White space may appear between a combinator and the
simple selectors around it. <a name=whitespace></a>Only the characters
"space" (U+0020), "tab" (U+0009), "line feed" (U+000A), "carriage return"
(U+000D), and "form feed" (U+000C) can occur in whitespace. Other
space-like characters, such as "em-space" (U+2003) and "ideographic space"
(U+3000), are never part of whitespace.
<p>The elements of a document tree that are represented by a selector are
the <dfn id=subjects-of-the-selector><a name=subject></a>subjects of the
selector</dfn>. A selector consisting of a single sequence of simple
selectors represents any element satisfying its requirements. Prepending
another sequence of simple selectors and a combinator to a sequence
imposes additional matching constraints, so the subjects of a selector are
always a subset of the elements represented by the last sequence of simple
selectors.
<p>An empty selector, containing no sequence of simple selectors and no
pseudo-element, is an <a href="#Conformance">invalid selector</a>.
<p>Characters in Selectors can be escaped with a backslash according to the
same <a href="http://www.w3.org/TR/CSS21/syndata.html#characters">escaping
rules</a> as CSS. <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>.
<p id=nsdecl>Certain selectors support namespace prefixes. The mechanism by
which namespace prefixes are <dfn id=declared>declared</dfn> should be
specified by the language that uses Selectors. If the language does not
specify a namespace prefix declaration mechanism, then no prefixes are
declared. In CSS, namespace prefixes are declared with the <a
href="http://www.w3.org/TR/css3-namespace/#declaration"><code>@namespace</code></a>
rule. <a href="#CSS3NAMESPACE"
rel=biblioentry>[CSS3NAMESPACE]<!--{{!CSS3NAMESPACE}}--></a>
<h2 id=grouping><span class=secno>5. </span>Groups of selectors</h2>
<p>A comma-separated list of selectors represents the union of all elements
selected by each of the individual selectors in the list. (A comma is
U+002C.) For example, in CSS when several selectors share the same
declarations, they may be grouped into a comma-separated list. White space
may appear before and/or after the comma.
<div class=example>
<p>CSS example:
<p>In this example, we condense three rules with identical declarations
into one. Thus,
<pre>h1 { font-family: sans-serif }
h2 { font-family: sans-serif }
h3 { font-family: sans-serif }</pre>
<p>is equivalent to:
<pre>h1, h2, h3 { font-family: sans-serif }</pre>
</div>
<p><strong>Warning</strong>: the equivalence is true in this example
because all the selectors are valid selectors. If just one of these
selectors were invalid, the entire group of selectors would be invalid.
This would invalidate the rule for all three heading elements, whereas in
the former case only one of the three individual heading rules would be
invalidated.
<div class=example>
<p>Invalid CSS example:
<pre>h1 { font-family: sans-serif }
h2..foo { font-family: sans-serif }
h3 { font-family: sans-serif }</pre>
<p>is not equivalent to:
<pre>h1, h2..foo, h3 { font-family: sans-serif }</pre>
<p>because the above selector (<code>h1, h2..foo, h3</code>) is entirely
invalid and the entire style rule is dropped. (When the selectors are not
grouped, only the rule for <code>h2..foo</code> is dropped.)
</div>
<h2 id=simple-selectors><span class=secno>6. </span>Simple selectors</h2>
<h3 id=type-selectors><span class=secno>6.1. </span>Type selector</h3>
<p>A <dfn id=type-selector>type selector</dfn> is the name of a document
language element type written using the syntax of <a
href="http://www.w3.org/TR/css3-namespace/#css-qnames">CSS qualified
names</a> <a href="#CSS3NAMESPACE"
rel=biblioentry>[CSS3NAMESPACE]<!--{{!CSS3NAMESPACE}}--></a>. A type
selector represents an instance of the element type in the document tree.
<div class=example>