This is a Plasma panel at height 30:
This is a Noctalia panel at the same height:
I think the latter looks better, with tray icons in smaller size.
The panel separator seems to stop increasing margins for tray below height 30. Maybe we can tune the threshold down a bit (e.g. 20)? Or maybe we can make the “icon size: small” option in the tray to be always at least one size smaller than the “fit panel” option?

