Long dropdowns in 3 levels

Have a problem on a client site where they have very long drop downs and in three levels that I can't figure out. It works in full desktop mode, i.e. from 1920 resolution, but on smaller screens, i.e. 1440 x 900, the drop down goes below the view.

I don't want the drop downs in two columns because the third level drop downs make no sense then, i.e. confusing where to hover.

And making a scroll on the second level only make the third level not show at all.

It's the menu under the header link Produkter. And it's built dynamically as the actual product categories comes in through their business system (Visma).

Have been searching and searching but can't find a solution for it. Anyone have any ideas?

The dev site is at https://intrado.firstvisiondev.se/