A small thing first: the favicon (the little picture that appears in front of the URL in the address bar) isn't a paw print! With the name and the use of paw images I'd expect the favicon to be a paw to0.
A couple pf bigger things:
The background boxes don't line up properly in Firefox.
There is a long section of text under the main screen on the home page in Firefox. It isn't supposed to be visible (and isn't in IE) and has been hidden by a technique called negative positioning. That is to say that it is supposed to appear off the top of the viewable area thus making it not visible to us the viewer.
I'm not sure why the technique isn't working in Firefox (it has worked for me in the past) but it doesn't look very good (though remember most visitors won't be scrutinising the site the way we are and may never scroll down to it).