[selectors] markup tweak

Author: tabatkins

selectors/Overview.bs

@@ -1474,12 +1474,12 @@ Attribute presence and value selectors</h3>
 			Represents an element with the <code>att</code> attribute,
 			whatever the value of the attribute.
 
-		<dt>''[att=val]''
+		<dt><css>[att=val]</css>
 		<dd>
 			Represents an element with the <code>att</code> attribute
 			whose value is exactly "val".
 
-		<dt>''[att~=val]''
+		<dt><css>[att~=val]</css>
 		<dd>
 			Represents an element with the <code>att</code> attribute
 			whose value is a <a href="#whitespace">whitespace</a>-separated list of words,
@@ -1490,7 +1490,7 @@ Attribute presence and value selectors</h3>
 			Also if "val" is the empty string,
 			it will never represent anything.
 
-		<dt>''[att|=val]''
+		<dt><css>[att|=val]</css>
 		<dd>
 			Represents an element with the <code>att</code> attribute,
 			its value either being exactly "val"

selectors/Overview.html

@@ -1712,12 +1712,12 @@ <h3 class="heading settled" data-level=6.1 id=attribute-representation><span cla
 			Represents an element with the <code>att</code> attribute,
 			whatever the value of the attribute.
 
-		<dt>''[att=val]''
+		<dt><span class=css>[att=val]</span>
 		<dd>
 			Represents an element with the <code>att</code> attribute
 			whose value is exactly "val".
 
-		<dt>''[att~=val]''
+		<dt><span class=css>[att~=val]</span>
 		<dd>
 			Represents an element with the <code>att</code> attribute
 			whose value is a <a href=#whitespace>whitespace</a>-separated list of words,
@@ -1728,7 +1728,7 @@ <h3 class="heading settled" data-level=6.1 id=attribute-representation><span cla
 			Also if "val" is the empty string,
 			it will never represent anything.
 
-		<dt>''[att|=val]''
+		<dt><span class=css>[att|=val]</span>
 		<dd>
 			Represents an element with the <code>att</code> attribute,
 			its value either being exactly "val"