[css3-grid-layout] Partially done rewrite of the subgrid section.

Author: tabatkins

css3-grid-layout/Overview.html

@@ -943,23 +943,24 @@ <h3 id=subgrids-the-subgrid-display-value><span class=secno>3.2.
   <p class=issue> This is a proposal to address the alignment of sub-items
    across grid items
 
-  <p> A grid item can itself be a grid element by giving it ‘<code
+  <p> A <a href="#grid-item"><i>grid item</i></a> can itself be a <a
+   href="#grid-container"><i>grid container</i></a> by giving it ‘<code
    class=css>display: grid</code>’; in this case the layout of its contents
    will be independent of the layout of the grid it participates in.
 
-  <p> In some cases it might be necessary for the contents of multiple grid
-   items to align to each other; in this case ‘<code class=css>display:
-   subgrid</code>’ can be used. A grid item with ‘<code
-   class=css>display: subgrid</code>’ behaves just like one with ‘<code
-   class=css>display: grid</code>’ except that:
+  <p> In some cases it might be necessary for the contents of multiple <a
+   href="#grid-item"><i>grid items</i></a> to align to each other; in this
+   case ‘<code class=css>display: subgrid</code>’ can be used. A <a
+   href="#grid-item"><i>grid item</i></a> with ‘<code class=css>display:
+   subgrid</code>’ behaves just like one with ‘<code class=css>display:
+   grid</code>’ except that:
 
   <ul>
-   <li> The ‘<code class=property>grid-column-definition</code>’ and
-    ‘<code class=property>grid-row-definition</code>’ properties do not
-    apply. Instead the number of explicit tracks is given by its ‘<code
-    class=property>grid-column-span</code>’ and ‘<code
-    class=property>grid-row-span</code>’ properties, and their sizes are
-    determined by the parent grid.
+   <li> The ‘<a href="#grid-definition-columns"><code
+    class=property>grid-definition-columns</code></a>’ and ‘<code
+    class=property>grid-definition-row</code>’ properties do not apply.
+    Instead the number of explicit tracks is given by its <a
+    href="#grid-span"><i>grid span</i></a>.
 
    <li> The used ‘<code class=property>grid-column-span</code>’ and
     ‘<code class=property>grid-row-span</code>’ of the item is determined

css3-grid-layout/Overview.src.html

@@ -631,17 +631,22 @@ <h3>Subgrids: the ''subgrid'' 'display' value</h3>
 		This is a proposal to address the alignment of sub-items across grid items
 
 	<p>
-		A grid item can itself be a grid element by giving it ''display: grid''; in this case the layout of its contents will be independent of the layout of the grid it participates in.
+		A <i>grid item</i> can itself be a <i>grid container</i> by giving it ''display: grid''; 
+		in this case the layout of its contents will be independent of the layout of the grid it participates in.
 
 	<p>
-		In some cases it might be necessary for the contents of multiple grid items to align to each other; in this case ''display: subgrid'' can be used. A grid item with ''display: subgrid'' behaves just like one with ''display: grid'' except that:
+		In some cases it might be necessary for the contents of multiple <i>grid items</i> to align to each other; 
+		in this case ''display: subgrid'' can be used. 
+		A <i>grid item</i> with ''display: subgrid'' behaves just like one with ''display: grid'' except that:
+
 	<ul>
 		<li>
-			The 'grid-column-definition' and 'grid-row-definition' properties do not apply.
-			Instead the number of explicit tracks is given by its 'grid-column-span' and 'grid-row-span' properties,
-			and their sizes are determined by the parent grid.
+			The 'grid-definition-columns' and 'grid-definition-row' properties do not apply.
+			Instead the number of explicit tracks is given by its <i>grid span</i>.
+
 		<li>
 			The used 'grid-column-span' and 'grid-row-span' of the item is determined by the number of grid rows and grid columns it contains.
+
 		<li>
 			Its own grid items participate in the sizing of its parent grid and are aligned to it.
 			In this process, the sum of the item's margin, padding, and borders are applied as an extra layer of margin to the items at those edges.