[juped]

Interesting, I've always experienced everything under the sun depending on specifically adwaita (I don't use any DE).

[ColonelPhantom]

That's probably libadwaita (the successor to libhandy), which by the way also forces the Adwaita GTK theme. This post is about the Adwaita _icon_ theme. Those are 3 different components (solib, CSS, icons) that all happen to be called Adwaita.