There was a dark theme until a few days ago when it changed to the default light theme.
Dark Theme no longer exists.
In the future, we will launch another similar theme if possible. stay tuned. but do not push it by asking again and again, we will do our best release it soon, no requesting!
Good luck! 
i was about to ask the same thing. i cant read the forum for more than 5 or 10 mins max without getting a nasty headache from the brightness xd
Chrome and other chromium based browsers have dark mode flag to turn any website dark.You can use it to enable dark mode
chrome://flags/#enable-force-dark
Install the chrome extension Dark Reader & turn it on.