I tried reloading it and it didn't work. Coming back later didn't help either. Neither does going fullscreen. Here's a screenshot of where it gets stuck:
I'm on Chrome if that helps... Also, same thing is happening for me on gdgames :\
ok so it seems to be up to chance somehow, because 3 people have already said they didnt get stuck, and at least 2 were on Windows and Chrome like you, I'll still try to fix it though
