shell: use CSS variables instead of GTK named colours
With libadwaita 1.6, CSS variables are used for colour variables, making it possible to override them in CSS. As such, this clean-up provides the practical improvment that it will pick up accent colour overrides.
This needs GNOME/gtk!7306 (merged)
that is not yet in a release
Signed-off-by: default avatarMarkus Göllnitz camelcasenick@bewares.it Signed-off-by: default avatarPablo Correa Gomez ablocorrea@hotmail.com