Oddly enough, I don't like dark themes, except on youtube (so it doesn't distract from the video). :)
I am going to make an option where it has everything except the dark theme, so I can use it to get the new quote stuff.
I haven't tried the forum from a vr browser, I'll take a look.
I just tested, the dark mode works in Firefox for android too. After installing Stylus (there doesn't seem to be a chrome android version, but Firefox has it), go to the github link I gave above. It won't install though. Go to the firefox menu and select "Request Desktop Site". Now it will pick up the script and install. Go back to the menu and turn off the desktop site option.
I may need to modify it a bit for mobile though, the bigger avatars mean less post area on screen.