https://chrome.google.com/webstore/detail/github-dark-theme-one-dar/nibmbfkmlnfmkfohcejnncjonfepppkk
This package will change appearance of all Github pages to dark theme, mostly based on Atom One Dark. Also changed font for code to support ligatures (requires https://github.com/tonsky/FiraCode installed locally).
yarn run build
Use Codemirror styles from https://github.com/StylishThemes/GitHub-Dark/tree/master/themes/codemirror