I uploaded the latest version now.

I resolved the problem by increasing the height of the div above the thumbnails ("#right") by 5px. I'm not sure why it worked but it did!

I do have one minor cosmetic difference with this site when opened in Firefox & IE. In IE there is a small gap between the header image and the navbar below. In this gap, which is only around 1-2px, you can see the background image. However, in Firefox this gap is not apparent.

This is my first website so I wanted to do it right using CSS for layout. Can you see if there's anything obvious i've done incorrectly in relation to the CSS or HTML before I carry on much further?