This is a cool concept! It was a bit annoying to have the page scroll when I hit up/down. Also, it seems like the note window (the time where it accepts a key to control the snake) was only AFTER the actual note? If I hit the key barely before (or even sometimes right on) the note, it wouldn't move. It would have been nice if the window was before and after the note.
With some faster music and more interesting rhythms, this would be really cool! Nice job.