How to reflow the layout on screen orientation change

Hi !
A quick question - how can I make the layout to reflow, when I change my screen orientation?
I understand the logic of Groups, Containers, Columns, Rows and different Alignment and Distribution options, yet I can’t achieve this. It seems I’m missing something.
Example - a Group with two subgroups, each containing three boxes. How can I make the two subgroups to reflow from side-by-side to top-bottom depending of the screen orientation :