Speed up scrolling

I removed the fixed background, as it was causing a full page reflow under Chrome. In particular, this speeds up the scrolling on show pages with lots of episodes. I'm getting repaints of 0.3-0.5 ms instead of 200-300ms, so it's smooth as butter now :+1: 

Was there a reason the background was fixed? It's a very subtle pattern, so I didn't see any reason it should be.