In Firefox, if you put a list into a div, and you want to add background color, be sure to set the height attibute of the div in css, otherwise you won't see the background color.
Reason why:
When you float the list items, they are moved out of the normal document flow, so what you are seeing in Firefox is a background color being applied to a <div> that has zero height. One way to get around thisis to set a height or a min-height on the ul
