Clarify that reserved keywords are reserved in all case permutations.

Author: fantasai

css3-values/Overview.html

@@ -636,7 +636,8 @@ <h3 id=identifiers><span class=secno>3.2. </span> User-defined Identifiers:
   <p> The <a href="#common-keywords">CSS-wide keywords</a> are not valid <a
    href="#identifier-value"><var>&lt;custom-ident>s</var></a>. The ‘<code
    class=css>default</code>’ keyword is reserved and is also not a valid <a
-   href="#identifier-value"><var>&lt;custom-ident>s</var></a>.
+   href="#identifier-value"><var>&lt;custom-ident>s</var></a>. These reserved
+   keywords are reserved in all ASCII case permutations.
 
   <h3 id=strings><span class=secno>3.3. </span> Quoted Strings: the ‘<a
    href="#string-value"><code class=css>&lt;string></code></a>’ type</h3>

css3-values/Overview.src.html

@@ -323,6 +323,7 @@ <h3 id="identifiers">
   <p>
 	The <a href='#common-keywords'>CSS-wide keywords</a> are not valid <var>&lt;custom-ident>s</var>.
 	The ''default'' keyword is reserved and is also not a valid <var>&lt;custom-ident>s</var>.
+	These reserved keywords are reserved in all ASCII case permutations.
 
 <h3 id="strings">
 Quoted Strings: the ''&lt;string>'' type</h3>