The problem is only in Firefox.
Part of the css:
#site-wrapper should always be from top to down, even if the page is very short. Inside IE and Chrome look just as it shild but inside Firefox if the page is short and there is no scroller - it is ok, but if the page is little bit longer - from the down side apears some space between #site-wrapper and the end of the page.
[edited by: alt131 at 5:57 pm (utc) on Feb 1, 2012]
[edit reason] Thread Tidy [/edit]