Help: CSS Conflict

Please help. I can't figure out what is going wrong with my CSS but it seems to be conflicting with phpBB's CSS.

Go to http://tinyurl.com/pz2us which should be a History page. Most other pages don't work yet but click "Forums" and you'll see the Red template still works fine.

Now go back to "History" and then click the little blue square below the menu, which will change to an alternate web 2.0 styled theme. Looks different but still looks fine, right? Notice there's plenty of room beneath the top navigation links, and that the little style squares are now up in the top right corner.

Now while in the "web 2.0" style, click the "Forums" link and see how it gets screwed up. Notice that the forums now overlap some of the menu items, and those style squares are bunched up oddly. My "Red" theme worked fine with phpBB but my "web 2.0" style freaks out.

Does anybody have any suggestions as to why this page plus this theme equals mess up? The CSS for this style can be seen here, and "#content is the div that seems to be shoving up too far only when on phpBB. You'll immediately notice that I reposition the div up 40 pixels but it should look like it does on the history page. It looks like it shifts up 100px on the phppBB page. Any ideas? Thanks.