"Works" fine in FF 5.0.1 and Lion. I use the term very loosely as that "Enter" link is both stupid and redundant. Why make a user click another button just to see what's on your site. "Hello! I came to your site and you won't show it to me. Why do you have the "door" closed?
And secondly, the wind then opens full-screen! There may be a javascript doing that or it may be the "feature" in Lion. Either way, it is imposing the developers desires instead of the viewers/customers/users wants. Who gave them that right?
OK, the stupid "closed front door" page does not work with javascript disabled. That's fine by me, however, since it seems to enable so much other unpleasant behavior. But make sure you have javascript enabled and see if that helps. You may also have some javascript protection Add-ons that are preventing the javascripts from running. With so much progress being made with CSS3 and html5, the days of javascript dangers and overuse are hopefully ending.
Of course, that won't mean much as long as web-designers rely on what they thought they had to or could do.