Wolff Playing with Beez!
Works pretty well on Facebook. ALLOT of sites are finally supplying a dark mode like Twitter and Deviant Arts but some do not. So this does come in handy. What you want to do is Enable for All Websites and then on the sites that you don't want it affecting just click the Website Toggle button to off or on. The changes are immediate so you don't have to reload the page as you do with some of these add ons!