It does what it says it does, however, it increases page load times by an unacceptable amount. Pages load instantly with the extension disabled. With it on, load times are anywhere from 3 to 5 seconds. That doesn't sound like a lot until you're sitting through it on every page load. And those 3 to 5 seconds add up after just a few minutes of browsing. Honestly this extension shouldn't even have to exist. There's no reason Firefox doesn't have a native dark mode like literally every other browser does. I thought this would be the fix, but it comes up a little short for me.