I find the 'home icon, Forums, Members, Donations, etc' menu header and the next line menu of 'mark forums read, search forums, watched forums, etc.' header jumping around to take up room at the top no matter where on the page I've scrolled to an unneeded css feature, and somewhat annoying. My vote would be for a non-moving header that just stays in one place. One can always scroll up to it when any of those item selections are needed.
Otherwise, great forum.
Otherwise, great forum.