Dark Mode support

[MoOx]

Hi,

I never used your lib yet, but very interested to (as I was starting to do a similar thing). One thing I noticed is that I don't see dark colors (eg: iOS Colors have light & dark values, which are different, same for grey, see https://developer.apple.com/design/human-interface-guidelines/ios/visual-design/color/)

Is there any plan to handle that? Might be a bit breaking change for color as the api should change (or we could add new api & keep legacy one for backward compat).

[HigorAlves]

@hectahertz Please assign this to me