https://gwern.net/index
The dark mode on that site is awful, I had to immediately toggle to light mode.
I haven't noticed, because I don't use dark mode, instead relying on dimming brightness and contrast of my displays while having soft and warm background illumination :-)
In light mode I miss some color themeing, like soft/warm something yellowbrown/manilapaperstyle instead of that hard black&white, but it still 'works for me' that way.
Or maybe a lighter grey like https://fabiensanglard.net/
If that were the case, I think something like this should be the default(on dektop) for wikipedia.