Operating system: Mac 10.6.8, tried on Chrome, Safari, and Firefox. The essential problem, it seems, is some miscommunication between the cursor and duolingo—normally things work fine, but basically anything on hover doesn't want to respond when my cursor is put over it, and this is especially a problem when trying to learn a new word during lessons or practice. (Don't know why it's doing this, but I can't enter text right now either...) Thank you for your help!