[css-variables-1][editorial] Add a shorter local-lt for 'substitute a var()'.

Author: tabatkins

css-variables-1/Overview.bs

@@ -79,7 +79,7 @@ Value Definitions</h3>
 Defining Custom Properties: the '--*' family of properties</h2>
 
 	This specification defines an open-ended set of properties called <a>custom properties</a>,
-	which, among other things, are used to define the <a lt="substitute a var()">substitution value</a> of ''var()'' functions.
+	which, among other things, are used to define the [=substitute|substitution value=] of ''var()'' functions.
 
 	<pre class='propdef'>
 	Name: --*
@@ -559,9 +559,9 @@ Using Cascading Variables: the ''var()'' notation</h2>
 	and those functions are syntactically valid,
 	the entire property's grammar must be assumed to be valid at parse time.
 	It is only syntax-checked at computed-value time,
-	after ''var()'' functions have been <a lt="substitute a var()">substituted</a>.
+	after ''var()'' functions have been [=substituted=].
 
-	To <dfn export lt="substitute a var()|var() substitution">substitute a var()</dfn> in a property's value:
+	To <dfn export local-lt="substitute" lt="substitute a var()|var() substitution">substitute a var()</dfn> in a property's value:
 
 	<ol>
 		<li>
@@ -578,7 +578,7 @@ Using Cascading Variables: the ''var()'' notation</h2>
 			Otherwise, if the ''var()'' function has a fallback value as its second argument,
 			replace the ''var()'' function by the fallback value.
 			If there are any ''var()'' references in the fallback,
-			<a lt="substitute a var()">substitute</a> them as well.
+			[=substitute=] them as well.
 
 		<li>
 			Otherwise,
@@ -612,7 +612,7 @@ Using Cascading Variables: the ''var()'' notation</h2>
 		</pre>
 	</div>
 
-	''var()'' functions are <a lt="substitute a var()">substituted</a> at computed-value time.
+	''var()'' functions are [=substituted=] at computed-value time.
 	If a declaration,
 	once all ''var()'' functions are substituted in,
 	does not match its declared grammar,