Dark Mode

[mattloose]

Is your feature request related to a problem in existing functionality or a lack thereof? Please describe.
I'm always frustrated when I can't turn on dark mode.

Describe the solution you'd like.
I'd like to be able to turn on dark mode.

Describe alternatives you've considered
I've tried switching off my screen and it does, indeed, go dark. But I can no longer see any of my lovely content.

Additional context
See https://dev.to/sbrevolution5/creating-a-toggleable-dark-mode-theme-ned