[chromatin]

The UX is awful - I bailed out at 25/100 JUST IN LEVEL ONE (BASICS)

Might I suggest adaptive difficulty? After getting 10, 15, 20 correct in a row it should scale up the difficulty immediately, rather than waiting for 100 in the basic level 1...

[scary-size]

Check button hidden under the URL bar thing in safari, progress bar hidden when scrolling check button in view. In between endless whitespace.