Banner alignment failure

[Syntax21121]

Hy all,

I've put in a new theme, and for some reason the banner extends to the right further than the container as you can see in the screenshot.

I can't remember how to fix it. Haven't really found anything on it as well.

Thanks kindly....

http://rulesofcombat.net/screen.jpg

[RichieBoy67]

I think you could add:
overflow: hidden;

Or

width: 100%;