Fix bookmarks menu on current Firefox (124)

This MR fixes the bookmarks popup on current Firefox. It was intended to be a pure port-over of user0's fixes (which worked fine on Plasma Mobile). In last minute testing, it turned out to be broken on Sxmo, as it kept covering the keyboard there.

This implementation is closer to the previous implementation and does not have the issue.

Find attached the before and after for current (124) and (ESR):

Screenshots: Dark ESR, bright 124

Before:

After: