My test page validates both for XHTML Transitional and CSS,
correctly in IE7, but Firefox is not showing a div background
and the nested
divs aren't obeying the width rule. It looks like there is a
problem, but I don't know enough to decide that without help.
Could you post a screenshot of what it should look like in IE
7? I tried using Browsershots but your server is kicking back a 403
error saying that their IP has been banned. BTW, the problem seems
to be in Firefox and Safari.