Just playing around with the dark mode and it really needs quite a bit of work to be properly integrated into the MacOS.
Safari really needs to be able to switch the CSS of webpages so white becomes black/dark etc. Yes you can use the reader mode.
It might be useful for pro-applications, it works nicely when using the photos app I have to admit.
The news app really should be able to switch the white background to black
It would also be helpful to have a button to switch the dark mode on and off at different times of day/night like night shift function. But also the background needs to be able to switch to a different default too.