I've used the Solus forum for years, all the while wishing that there were a dark mode that would give my eyes a break. Recently, I was curious about the little icon just to the left of the notifications bell, and clicked it. It's the one that looks like a little sun.
You guessed it -- instant eye relief! Given of the popularity of dark themes these days, I thought there might be others here who would appreciate knowing about it, so I thought I'd point it out.
That icon is a toggle, so if you try it and find you don't like it, just click it once more.