Index: wp-content/themes/twentyten/style.css
===================================================================
--- wp-content/themes/twentyten/style.css	(revision 15287)
+++ wp-content/themes/twentyten/style.css	(working copy)
@@ -453,6 +453,7 @@
 -------------------------------------------------------------- */
 
 #main {
+	clear: both;
 	overflow: hidden;
 	padding: 40px 0 0 0;
 }