How to animate the appearance of scrolledwindow > overshoot/undershoot?

[p3732 (Peter Eisenmann)]

Hej, I was wondering if there is a (preferably simple) way to animate displaying an undershoot. In my CSS I currently have this (GTK4 + libadwaita):

.scrollable-container > scrolledwindow undershoot.bottom {
  background: linear-gradient(to top, alpha(@shaded_card_bg_color, 1) 0px, alpha(@shaded_card_bg_color, 0) 18px);
}

Setting a transition property does not do anything, I suppose that is because the undershoot is shown by toggling a visibility flag.

Does anyone know a way of how to achieve this? Or does it require upstream changes?

[alicem (Alice Mikhaylenko)]

You can’t atm, it needs to be ported to a widget instead of a CSS node. Shouldn’t be a big change, but someone needs to do it.