What I am trying to do for desktop is to display the left column on the left, the right column on the right and the full width column under the left and right. Then on tablet and mobile have the left column full width followed by the full width column and then the right column full width.
I suppose that’s a hack with floats, the script just alters the class, right?
I was just trying a Pen with the html above, but I don’t think it will work with that structure.
This one is old-skool floats, without any new-fangled flex box:-
They seem to behave the same, but that may alter with “real” content.
But this may not help the OP as it requires to change the html structure and may not fit in with the framework which makes RWD so simple and easy.