Add darkmode support that respect select theme

I’ve given this some thought in the past… and decided not to implement dark mode. There are probably too many edge cases that I won’t be able to provide support for. e.g. some plugin’s admin screeen doesn’t look nice in dark mode, and ASE users will be asking me to support it, etc. Not worth the effort for the ‘cool’ of dark mode. I prefer dedicating time and effort to improve other areas of WordPress.

There are already dark mode plugins, and I guess some of them would work nicely for people who need it.