[css-grid] De-dupe introductory sentence.

Author: fantasai

css-grid/Overview.bs

@@ -228,26 +228,6 @@ Declaring the Grid</h3>
 		</ul>
 	</div>
 
-	The resulting grid is <a href="#grid-align">aligned</a> within the <a>grid container</a>
-	by means of the 'align-content' and 'justify-content' properties.
-	[[#alignment]]
-
-	<div class="example">
-		The following example justifies all columns
-		by distributing any extra space among them,
-		and centers the grid in the <a>grid container</a>
-		when it is smaller than 100vh.
-
-		<pre>
-			main {
-				grid: auto-flow 1fr / repeat(auto-fill, 5em);
-				min-height: 100vh;
-				justify-content: space-between;
-				align-content: safe center;
-			}
-		</pre>
-	</div>
-
 <h3 id="overview-placement">
 Placing Items</h3>
 
@@ -297,8 +277,27 @@ Sizing the Grid</h3>
 	Once the <a>grid items</a> have been <a href="#placement">placed</a>,
 	the sizes of the <a>grid tracks</a> (rows and columns) are calculated,
 	accounting for the sizes of their contents and/or available space as specified in the grid definition.
-	The sized grid is then aligned within its <a>grid container</a>
+
+	The resulting sized grid is <a href="#grid-align">aligned</a> within the <a>grid container</a>
 	according to the <a>grid container</a>’s 'align-content' and 'justify-content' properties.
+	[[#alignment]]
+
+	<div class="example">
+		The following example justifies all columns
+		by distributing any extra space among them,
+		and centers the grid in the <a>grid container</a>
+		when it is smaller than 100vh.
+
+		<pre>
+			main {
+				grid: auto-flow 1fr / repeat(auto-fill, 5em);
+				min-height: 100vh;
+				justify-content: space-between;
+				align-content: safe center;
+			}
+		</pre>
+	</div>
+
 	Finally each <a>grid item</a> is sized and aligned within its assigned <a>grid area</a>,
 	as specified by its own sizing and alignment properties.