Fix minor css issue in Firefox

Firefox shows the scrollbar when mouse moves over the content section on
the community page: https://grails.apache.org/community.html

All content is visible

Author: dauer

assets/stylesheets/screen.css

@@ -273,7 +273,6 @@ li {
 .content {
 	margin: 0 auto;
 	z-index: 2;
-	overflow: auto;
 }
 
 .content {