Make the cascading behavior of @counter-style slightly clearer.

Author: tabatkins

css3-lists/Overview.html

@@ -1479,6 +1479,10 @@ <h2 id=counter-style><span class=secno>8. </span> Defining Custom Counter
    declaration "wins": first, they are compared by origin, with author rules
    beating user rules, and user rules beating UA rules; second, they are
    compared by document order, with later rules beating earlier rules.
+   &lsquo;<code class=css>@counter-style</code>&rsquo; rules cascade
+   "atomically" - if one replaces another of the same name, it replaces it
+   <em>entirely</em>, rather than just replacing the specific descriptors it
+   specifies.
 
   <p>This at-rule conforms with the forward-compatible parsing requirement of
    CSS; parsers may ignore these rules without error. Any descriptors that

css3-lists/Overview.src.html

@@ -895,7 +895,7 @@ <h2 id='counter-style'>
 	multiple times in a given @counter-style rule, only the last specified value
 	is used; all prior values for that descriptor must be ignored.</p>
 
-	<p>Defining a ''@counter-style'' must make it available to the entire document in which it is included.  If multiple ''@counter-style'' rules are defined with the same name, standard cascade rules must be used to determine which declaration "wins": first, they are compared by origin, with author rules beating user rules, and user rules beating UA rules; second, they are compared by document order, with later rules beating earlier rules.</p>
+	<p>Defining a ''@counter-style'' must make it available to the entire document in which it is included.  If multiple ''@counter-style'' rules are defined with the same name, standard cascade rules must be used to determine which declaration "wins": first, they are compared by origin, with author rules beating user rules, and user rules beating UA rules; second, they are compared by document order, with later rules beating earlier rules.  ''@counter-style'' rules cascade "atomically" - if one replaces another of the same name, it replaces it <em>entirely</em>, rather than just replacing the specific descriptors it specifies.</p>
 
 	<p>This at-rule conforms with the forward-compatible parsing requirement of CSS; parsers may ignore these rules without error. Any descriptors that are not recognized or implemented by a given user agent must be ignored.  The <i>&lt;counter-style-name></i> must be be a valid identifier and must not be "decimal", "default", "inherit", "initial", "inside", "none", or "outside"; otherwise the @counter-style is invalid and must be ignored.</p>