OK...What you have here is the same problem I had with my first php-nuke site..
The "theme" that you have installed at that link is a theme that runs in what I call a 800x600 size all the time, your other theme at
http://www.bravoclan.com/2ndrb/index.php is what I like to call an auto resizing theme, it doesn't make a difference if the display is 800x600, 1024x768, or what ever, it will just resize the theme to match what ever resoution the userrs monitor is running in
The Fourms area problem:
Well what you have here is an incomplete theme, the got the main theme don't but never got around to making the theme match for the fourms area...you will find that LOTS of the themes out there have this problem (as well as the 800x600 theme problem)
TO fix the problem so that the theme does cover the whole page and be fixed in two ways:
simple>>> change the display setting for your video card (800x600 should work) LOL
Hard>>>recreate the complete theme...