It’s CSS. A lot of sites use position CSS to fix the position of page elements like this.
Since blocking all CSS isn’t really an option, you can use Greasemonkey to remove the “postion:fixed” CSS from the “#yucsHead” identifier, or just add “display:none” to the same identifier to hide it completely. (I assume. I’ve never actually used Greasemonkey, but that CSS will work for you if you can find a way to inject it.)