[css-grid] Update example to new syntax for subgrids. We might want to consider improving the shorthand here...

Author: fantasai

css-grid/Overview.src.html

@@ -1008,7 +1008,7 @@ <h4 id="subgrids">
 	<p>
 		A <a>subgrid</a> behaves just like a normal <a>grid container</a> except that:
 
-	<ul>
+	<ul style="list-style-type: lower-alpha">
 		<li>
 			The number of explicit tracks is given by its <a>grid span</a>,
 			rather than by 'grid-template-rows'/'grid-template-columns'.
@@ -1074,7 +1074,8 @@ <h4 id="subgrids">
 	grid-template-columns: auto 1fr;
 }
 li {
-	display: subgrid;
+	display: grid;
+	grid: subgrid / subgrid;
 	margin: 0.5em;
 	border: solid;
 	padding: 0.5em;