How does the config folder "gtk-4.0" work?

You can put gtk.css in there and it changes the colors of the style sheet. But my question: does there exist a way to target dark and light separately?

At the moment if I were to target certain elements, it would change them regardless of the dark/light style selected in gnome-control-center.

That does not exist. See Federico’s blog for a status report on the current state, and a description of how that could be done.

Please also note that gtk.css is a poor way to apply themes, it is only really useful for testing. Generally it is not possible to write one global CSS file that will apply correctly to every app.

that was a good and informative read. thanks :slight_smile: