GitHerb-Dark-OMV is "One More Variant" of GitHub Dark. The starting point for this theme was GitHub Dark Default.
Other cosmetics settings
I use Google Font 'Source Code Pro Medium'. You know the drill - web search for Google Fonts, find the font you want, download it's ttf file, and (on Windows machines) double click that file to install.
My cosmetics-related modifications to workspace file 'settings.json':
Feedback appreciated. Really.