Adwaita: avoid feeling dated
In a constant stream of interaction with @bertob and @Feichtmeier pushing for more contemporary elements, I think there's small gradual improvements how we can make Adwaita look less dated:
- Passive elements like progresbars, levebars etc can be flattened. They can also be a little rounder.
- Contrast/affordance of buttons can be make with fills as hovers are darkening now and buttons can be made lighter. What we raise in contrast we can tone down in gradient/bevel
- Text labels and buttons and headerbars don't need the embossed edge highlight.