So, I just started learning xhtml/css spending a few hours each evening following tutorials and reading guides etc.

I started with just layout/columns and now I'm trying to tackle menus before moving onto slicing psd and image positioning.

So I created the following yday evening but I'm having difficulty trouble shooting what is causing the small gap between the menu's most noticable when you hover over one of them:

The layout is here:
illtemper.co.uk/nova4/

Any other criticism/tips on my code is also welcome to increase efficiency and more semantic code etc.