BuddyPress.org

@kippnkatie – I would strongly recommend learning some elementary CSS. Using the Firebug plugin with Firefox also helps immensely.

Replace your following snippet above with:
#members-dir-list .item-list li, #groups-dir-list .item-list li {clear:both;margin:0 0 2em 0;padding:10px 0;}

This should fix both your members and groups directory.