The lesson and review buttons in the top bar toggle when you scroll halfway over the numbers on the big buttons. Just have them showing all the time, it doesn’t matter if there are two places to click when you’re at the top of the page. It’s less annoying and noticeable than the toggling imo.
Also the big buttons are pink for lessons and blue for reviews. But if you scroll down, the small buttons at the top are both purple, which is visually inconsistent.