I used to use an Electron wrapper for Google Play Music (may it rest in peace) and the developer of that did this. The default colour scheme for that product wa

I used to use an Electron wrapper for Google Play Music (may it rest in peace) and the developer of that did this. The default colour scheme for that product was a harsh orange, but the Electron client allowed you to override the CSS to change that base color, as well as switch between light/dark mode.