There are a lot of little bugs. Sometimes, I have to switch the extension off and on before it loads a side. Sometimes, when I add a site to my exceptions list it renders it as "dark" anyway. A lot of major sites (such as google.com) have parts of UI become invisible with this plug-in active (at least in dark mode). Kinda neat, but not up to the Chrome version yet.

Dark Mode - an extension I've been trying in this one's stead has a much smaller feature set but works far more reliably.