really bad alternative:
https://github.com/HunterC14/Useful_bookmarklets/blob/main/general/content.js#L21-L23
also you probably shouldn't trust random ppl's bookmarklets but just look at it, it's safe
type "black" when it asks you for the color

I am also in favor of this. 

I'm on it.

Edit: https://pastebin.com/CMNYhnfy

I got the CSS, but I want to make an extension as well.

Edit again: FINALLY finished!
https://www.mediafire.com/file/v0gdtv843ch3m22/TPT-Darkmode.zip/file

direct download: link

How to run it?

$68?Oh,no!