Yeah I'm sure about that; I see the [awesome] fixed positioning, but it so happens that with position: fixed; comes some attributes of position: absolute;, like "ignoring" other page elements. I'm scrolled all the way up.
In addition, I've found another bug; in the wiki, on the
integumentary system page for example, the relative urls you've got going on break apart with the introduction of another directory. First of all, the images disappear as seen with the logo and the black bar, and the href on the [missing] logo is "Main_Page" which is intended to bring you back to the index of the wiki, but of course it's going to go to Anatomy/Main_Page because of the extra slash. As the page doesn't exist (besides being not the page that's intended to come to when you click there), you get a 404.