Add custom css to site

[GorlikItsMe]

Feature request

It would be great if you could add your own css e.g. to make the code white and not gray etc.

Summary

Community would like to create its styles that will make the documentation more enjoyable. Adding a textarea field in the settings where you can paste the css would be good.

[simon04]

For injecting custom JS/CSS, I suggest Greasemonkey or similar extensions: https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/

If you'd like to contribute a new theme (in addition to the light/dark themes), I'm happy to review.

I personally will not implement the requested feature in devdocs, but I'm happy to review a PR.