Index: modules/forum.module
===================================================================
--- modules/forum.module	(revision 5735)
+++ modules/forum.module	(working copy)
@@ -922,7 +922,8 @@
           $new_topics = 0;
         }
 
-        $description  = '<div style="margin-left: '. ($forum->depth * 30) ."px;\">\n";
+        $class = ($new_topics > 0) ? 'newtopics' : 'nonewtopics';
+        $description  = '<div class="'.$class.'" style="padding-left: '. ($forum->depth * 30) ."px;\">\n";
         $description .= ' <div class="name">'. l($forum->name, "forum/$forum->tid") ."</div>\n";
 
         if ($forum->description) {