Wikipedia can change its appearance nowadays although it's a bit tricky.
You need to create a profile and change the appearance to "Minerva".

All they do is taking Wikipedia's hard work and making money out of it (which Wikipedia has always refused). Everyone's free to make money if done legally but that's a rude way of doing it (since Wikipedia lives from donations). My old laptop can't run it since Wikiwand is so modern. My last concern is that when the addon has been installed, even if you go to Wikipedia you'll be redirected
Btw, the sidebar doesnt work properly on pages with a lot of headers https://www.wikiwand.com/en/Collatz_conjecture

Looks much more professional than normal Wikipedia. If only people would donate to our beloved Wiki...

Very very good! If it get more options for customization (text color, more background colors) available, it would be just perfect!

Super sympa

One helluva superb add-on!
As daily Wikipedia user, this is a "must-have" tool!