Random gap...(CSS)

[Pharaoh]

Ok, I'm just starting to learn CSS and as a start, I've began to recode one of my websites using CSS (got rid of the table structure)

Ok, here's the page I'm having a problem with:
http://www.swcreations.co.uk/index3.php

As you will be able to see, in firefox it looks fine, and there is no gap. However, in IE there is a gap.

URL to CSS: http://www.swcreations.co.uk/style4.css

Any help or advice would be greatly appreciated.

[nets]

Apply the following declaration to the ID selector "column_left_top".

overflow: hidden;