This is what I got so far:
It isn't total fullscreen because you'd either have to stretch the canvas out to cover everything or have scrollbars I think, so this is the best I could do to keep the canvas proportional. Hitting the fullscreen text will make it resize vertically to the dimensions of the window and escape will move it back.
The code for it is at the bottom of the html file where the runtime code is, it's just a few lines.
Also apparently it doesn't work properly in IE. So give me a few more minutes to figure that out and it should work fine.