Index: modules/book.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/book.module,v
retrieving revision 1.288
diff -u -F^f -r1.288 book.module
--- modules/book.module	4 Apr 2005 21:32:21 -0000	1.288
+++ modules/book.module	6 Apr 2005 17:47:45 -0000
@@ -585,7 +585,7 @@ function book_tree($parent = 0, $depth =
   }
 
   if ($tree = book_tree_recurse($parent, $depth, $children, $unfold)) {
-    return '<ul>'. $tree .'</ul>';
+    return '<div class="menu"><ul>'. $tree .'</ul></div>';
   }
 }