Mark the grammar so you get operator linking.

Author: tabatkins

css-grid/Overview.bs

@@ -2693,7 +2693,7 @@ Line-based Placement: the 'grid-row-start', 'grid-column-start', 'grid-row-end',
 	Computed value: specified value
 	</pre>
 
-	<pre>
+	<pre class=prod>
 		<dfn for="grid-row-start, grid-column-start, grid-row-end, grid-column-end"><<grid-line>></dfn> =
 		  auto |
 		  <<custom-ident>> |