DIV tag won't align to top in FF

[gblasko]

Would anyone happen to have any suggestions as to how i can get this page to properly align to the top of the browser window in FireFox?

http://www.pttiming.com/testlayout.php

The layout looks correct in IE but as you will notive there is about a 5 pixel gap when viewing it in FF at the top.

Thanks much...

[Twey]

It's caused by the top margin on #topheader.