I don't know why Mike Mirzayanov is reluctant to add a dark theme into CodeForces. I went through this blog by sigma_g on how to set dark theme on codeforces but believe me it is not as good as it should be. If you are seeing this Mike please add dark mode, I am sure it won't take that longer for your developer to do this.
Here's how my codeforces looks like, I use midnight lizard extension and changed the black colour to grey.
Here's the settings I changed.
This one is good, wouldn't it be better if Codeforce comes with its own dark theme, not everyone likes the hassle of tweaking the settings of extensions.