I would also recommend this script which I’ve used for a long time (install it from first post, then manually update it with the modified script in the link).
It shows kanji you haven’t learned yet in a different colour. You can hover the mouse over kanji to get reading info. It also uses browser or Google Translate text-to-speech to read the sentences aloud if you prefer that. I found the Chrome TTS is quite good and sounds most natural.