AdSense Breaking Layout

I've been using AdSense on a few domains for a while, and have just set up a new site with an adsense footer at the bottom. The problem is, the footer seems to break through the rest of the page and mess up the background. I've tweaked it in Firebug for ages but I can't get it to stay within the width of the add (less than 500px).

How do I keep it in the middle?

http://sturly.com/adsensebroken

 

Try moving the div with adsense in it up. This is how it is at the moment:

Make it this:

 

Ah, I must have overlooked that. =)

Thanks.