can't roll over my words + bar strength
I'm using firefox when playing duolingo, and even after trying different browsers, I can't seem to use the vocab mouse over aspect of the game. Everytime i roll over a word, no definitions appear. Also, after mastering levels, it doesn't show me my strength in bars (like all my friends have - which decrease after a number of days after not reviewing). I only have hearts. Why is that? What should I do?