It does not work as expected with many themes. Text sections remain white and the links are a very light gray, too light to be readable. The best examples are the defasult Firefox themes. Tried on different installations. I removed this useless ezxtention from all of them.

I read on the FAQ:
"Our extensions only work on the desktop version of Google Chrome. So, it will not work on your phone, atleast as of now."
If the developer says so, it should no be on a Firefox offered estentions page.