I hope questions to Kvantum are not offtopic here....?

Software:

KDE/Plasma 5.18.6
Qt 5.12.7
kvantum-qt5 / kvantum-manager 0.19

I find the menu and selection bar a bit huge, even on a 1920x1080 display it used too much space IMHO, as you can see there:
https://ibb.co/M6S8Spj

How can I make the whole menu smaller, not necessarily the font, but the whole space between and that huge selection bar?

This is how I would like to have the menus, less space between:
https://ibb.co/YtgPGrj

I looked at ~/.config/Kvantum/KvCurvesLight#/KvCurvesLight#.kvconfig but there are so many options, with trial and error it would take ages to find out....

Thanks for any hint!