using Dark Reader (a browser plugin)
I use that too and it's a great idea. I'm working toward getting the designer's version of a dark theme as well, plus I want to see a toggle button (dark to light and back) always available. It's currently possible for a user to go back and forth by going into their "Control Panel" and selecting "Settings and Privacy," but that's probably more work than it should be. On sites that have a toggle button I switch back and forth fairly regularly depending on time of day.
Update - I had not been using Dark Reader recently with the new default theme but I just tried it and it does work very well, as Julia says!