Although http://gist.io has this already, I think I like mkdown's CSS a little better (though there doesn't seem to be <code> styling as of yet). In any case, great work!
I opened it and thought that pg would approve of the narrow column [0]. Then I looked who made it and saw that it's a founder of one of the best examples of YC (not just companies that are doing well but seem philosophically aligned with YC).
Edit: I was wrong, SeatGeek didn't go through YC. But the company is certainly well-liked around here, partly because of their open source: https://github.com/seatgeek/soulmate
