Need footer to clear sidebar

What I’m trying to do is a faux liquid layout (100% width <li> items through the middle) so I can get a nice color across the background of the most recent <LI> item, but all the content will appear to be 960px wide and centered in the site. And I’m having trouble coming up with a clever way to get the footer to clear the sidebar. Take a look at this image …

If there is only 1 item up top, let’s say just a FEATURED LI the footer still needs to obey the height of the div. Any thoughts? I can do this with jQuery, but was wondering about a nice CSS solution. Thanks.

I should note that the sidebar <UL> is positioned absolute, left: 50%, margin-left: -480px; That’s why the footer naturally ignores it, but I need that footer to pay attention to the length of the sidebar. Again, any help is appreciated.