Problem with nav & logo in Firefox

I have a cart at http://www.tnfairhousingmatters.net/zencart/. It looks fine in IE, but in Firefox, there's a white space or bar between the navwrapper and the logowrapper. I got rid of the default background image in the logowrapper and replaced it with a background color, so I'm guessing I just need to play with the positions or heights of these two elements. I'm using the classic template.

I'm having the exact same problem at http://www.quadstatefheo.com/cart, although the logowrapper in that one still has a background image, just not the default one.

Can anyone point me in the right direction?

Thanks,

Tracey

(Couldn't figure out how to edit my previous post)

Okay, the white bar I'm seeing is the "mainWrapper" element, which has a white background color. So obviously the logowrapper and the navwrapper elements need to come together somehow so that the white background is not showing between them. IE is handling this fine, but for some reason Firefox is not.

Thanks,

Tracey