Funny, when I first saw it I wasn't sure if my monitor was screwed up, whether someone had defaced HN or if some Chrome plugin was misbehaving. Though I eventually figured it out with the alternating red/green submission colors and HNSearching for "Christmas CSS". I also found out that you could change your topcolor and immediately set it to #000000 so people would stop pestering me when they saw I was reading a hacker website.