I recently heard about the Dark Reader extension for Chrome, which lets you toggle dark settings per website in a fairly intelligent way. https://chrome.google.com/webstore/detail/dark-reader/eimadp... I'm really liking it, and I'd be interested to hear about something similar for Firefox.
I'm not familiar with Dark Reader, but I'm guessing it's along the same lines. I've used it with Firefox Mobile for a couple months and have been happy with it.
