Uniform width for content below quick links and above footer

[wishtheend]

First, here's a link to my forum:
http://www.providermodule.com/forum/index.php

What I'm trying to do is make the width of the main forum body equally as wide as the header and footer. Right now, the main body shrinks in a little bit which kind of ruins the border that should be around the whole forum.

Doc_width isn't changing that part, so I'm guessing it might be a css section to edit. Any help would be appreciated.