Straight one: http://neecto.com/wtf/1.htm
Everything is fine. But if you comment or remove TopMenuBar's CSS Border attribute, than there's a space at the top which is here: http://neecto.com/wtf/2.htm (Check with Firefox 3.6, latest one)
Which also works fine in IE and Chrome. I feel so angry because I just gave my more than 3 hours without even drinking water to fix the problem. And the problem is a illogical stupid firefox issue.
Sorry for the language, really feel angry...