FireFox is ONLY compatible with the DEFAULT style menu buttons if you use submenus which can expand over any linkable items such as Lightboxes and hyperlinks. For any other menu style, FF delimits the menu expansion to be the area of the Menu itself. In other words, the menu borders must stretch as far to the right and as far to the bottom as waht the menu actaully expands to. However, FF does not see its background as transparent and therefore you cannot open hyperlinks or Lightboxes that are normally under this area.