Support dark mode brighening based on elevation

[cmeeren]

• I have searched the issues of this repository and believe that this is not a duplicate.

Summary 💡

According to the MD spec, for dark mode, surfaces with higher elevation should use lighter grays.

Examples 🌈

MD spec

Relevant screenshot of spec:

[oliviertassinari]

@cmeeren Thank you for opening an issue. Yes, we will have to rework this point for v5 :)

[miquelvir]

Any update? Is there any known workaround for now?

[oliviertassinari]

@miquelvir Do you want to resume the effort of #21748?

[miquelvir]

I would love to, but i am not qualified to... I am learning js and React right now so I am a beginner here (I have more xp in Java and Python)