Oh, I think I get you. You mean the static HUD isn't doing anything for you zooming in the board. That's an oversight on my part, thanks for the report.

Edit: also, you should be able to zoom in on the tiles, but, you're possibly running into an untested edge case, of which there are tons. Mac and mobile is under-developed as I'm a firefox/desktop curmudgeon. As you and others have noted, there is some interface goofery, but otherwise a mousewheel should let you zoom in until you see a moire pattern on a crt.