Vimium: Add dark theme

[Semro]

Since a lot of web pages have a dark theme it's good for Vimium to have that too. Opening vomnibar or help page on the dark page is painful.

[qx-775]

It is already possible to theme Vimium.

Have you tried reading the wiki? It is possible to theme vimium using custom themes https://github.com/philc/vimium/wiki/Theme
There is a dark theme included. Just copy paste into the CSS pane, just go to Vimium options -> Show Advanced Options -> Paste in CSS for Vimium UI

[Semro]

Thank you!

There is another problem that I am encountering on GitHub dark layout. Vimium UI elements background are white:

OS: Windows 10
Browser: Chrome Version 87.0.4280.88 (Official Build) (64-bit)
Vimium 1.66

The solutions found so far:
Add style:

iframe.vimiumUIComponentVisible {
    color-scheme: none;
}

(what can't be done through Vimium custom CSS)

or with some other extension make the same change to the html element of the GitHub page.

[BachoSeven]

@Semro

Regarding the dark theme: in addition to the already present possibility for manual theming, this PR implemented a global dark mode for vimium which respects the CSS prefers-color-scheme: dark, set by the OS. The feature has not been released in a new version yet, but you use the master version.

Your second issue is the same as #3732, this comment has the solution as yours :)

Feel free to close this if your issue is solved.