Aha! I think it is 250. I recently passed that, and after your post clicked my username to check...voila it's there. This will keep me amused for the next 2~20 minutes.
How can the top bar color change be of any use?
I just set mine to 212121 and, rather topically, now I can't make out from the top right corner how much karma I have. I suppose that could be used to remind a person that they've got work to do instead of checking if anyone has upvoted their stuff.