[e] (0) Add a note about hidden='' and CSS

Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=23428
Affected topics: HTML

git-svn-id: http://svn.whatwg.org/webapps@8295 340c8d12-0b0e-0410-8428-c7bf67bfef74

complete.html

@@ -298,7 +298,7 @@
 
   <header class=head id=head><p><a href=http://www.whatwg.org/ class=logo><img width=101 src=/images/logo alt=WHATWG height=101></a></p>
    <hgroup><h1 class=allcaps>HTML</h1>
-    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 18 November 2013</h2>
+    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 19 November 2013</h2>
    </hgroup><dl><dt><strong>Web developer edition:</strong></dt>
     <dd><strong><a href=http://developers.whatwg.org/>http://developers.whatwg.org/</a></strong></dd>
     <dt>Multiple-page version:</dt>
@@ -74674,6 +74674,12 @@ <h3 id=the-hidden-attribute><span class=secno>8.1 </span>The <dfn title=attr-hid
   requirements <a href=#hiddenCSS>using the rules suggested in the Rendering
   section</a>.</span></p>
 
+  <p class=note>Because this attribute is typically implemented using CSS, it's also possible to
+  override it using CSS. For instance, a rule that applies 'display: block' to all elements will
+  cancel the effects of the <code title=attr-hidden><a href=#the-hidden-attribute>hidden</a></code> attribute. Authors therefore
+  have to take care when writing their style sheets to make sure that the attribute is still styled
+  as expected.</p>
+
   <div class=example>
 
    <p>In the following skeletal example, the attribute is used to hide the Web game's main screen

index

@@ -298,7 +298,7 @@
 
   <header class=head id=head><p><a href=http://www.whatwg.org/ class=logo><img width=101 src=/images/logo alt=WHATWG height=101></a></p>
    <hgroup><h1 class=allcaps>HTML</h1>
-    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 18 November 2013</h2>
+    <h2 class="no-num no-toc">Living Standard &mdash; Last Updated 19 November 2013</h2>
    </hgroup><dl><dt><strong>Web developer edition:</strong></dt>
     <dd><strong><a href=http://developers.whatwg.org/>http://developers.whatwg.org/</a></strong></dd>
     <dt>Multiple-page version:</dt>
@@ -74674,6 +74674,12 @@ loadMySprites().then(runDemo);</pre>
   requirements <a href=#hiddenCSS>using the rules suggested in the Rendering
   section</a>.</span></p>
 
+  <p class=note>Because this attribute is typically implemented using CSS, it's also possible to
+  override it using CSS. For instance, a rule that applies 'display: block' to all elements will
+  cancel the effects of the <code title=attr-hidden><a href=#the-hidden-attribute>hidden</a></code> attribute. Authors therefore
+  have to take care when writing their style sheets to make sure that the attribute is still styled
+  as expected.</p>
+
   <div class=example>
 
    <p>In the following skeletal example, the attribute is used to hide the Web game's main screen

source

@@ -83464,6 +83464,12 @@ loadMySprites().then(runDemo);</pre>
   requirements <a href="#hiddenCSS">using the rules suggested in the Rendering
   section</a>.</span></p>
 
+  <p class="note">Because this attribute is typically implemented using CSS, it's also possible to
+  override it using CSS. For instance, a rule that applies 'display: block' to all elements will
+  cancel the effects of the <code data-x="attr-hidden">hidden</code> attribute. Authors therefore
+  have to take care when writing their style sheets to make sure that the attribute is still styled
+  as expected.</p>
+
   <div class="example">
 
    <p>In the following skeletal example, the attribute is used to hide the Web game's main screen