I like DarkReader, but it's been a huge exercise in patience seeing Firefox and Chrome getting all the updates, while the paid Safari version languishes.
By the extension author's own admission [1], the majority of the revenue comes from the Safari extension, but he still prioritizes the (I imagine) larger user base of the firfox and chrome extensions. It's frustrating, to say the least.
https://github.com/darkreader/darkreader
https://github.com/openstyles/stylus (not built into release yet)