There seems to be a few similar questions about this, so here's mine...

I want to have two adjacent columns rearrange to be vertically stacked. I've figured out how to do it with media queries but I'm trying to see if there's a way to avoid how it breaks without the media queries for those clients that don't support it.

I think you can best see what I mean here: https://litmus.com/builder/2b65caf

Notice at 600px the top one behaves correctly as I want it (uses media queries). Between 600px and 580px the bottom collumns (I've removed the class that is used in the media query) lose the space between them (not using anything to define the space, only aligning one table left and one right). After 580px the collumns stack but since they are aligned left/right they sit on opposite sides of the table, not centered like the top one.

Any way to avoid this, or to get a responsive vertical stack without media queries?