[css-backgrounds-4] Fixed display of issue for background-repeat: extend (#9129)

Author: SebastianZ

css-backgrounds-4/Overview.bs

@@ -185,8 +185,7 @@ Painting Area: the 'background-clip' property</h3>
 		</dd>
 	</dl>
 
-	<div class="issue">
-		Should a <a href="https://lists.w3.org/Archives/Public/www-style/2011Sep/0331.html">'background-repeat: extend'</a> be added?
+Issue: Should a <a href="https://lists.w3.org/Archives/Public/www-style/2011Sep/0331.html">'background-repeat: extend'</a> be added?
 
 <h2 id="changes">
 Changes</h2>