This example shows two items that stack vertically on small screens and become side-by-side on screens 'sm' (640px) and wider.
Resize your browser window to see the effect.
On small screens, "Item 1" and "Item 2" are stacked vertically.
On screens 640px wide or larger, they appear side-by-side.
Key classes used:
flex
,
flex-col
,
sm:flex-row
on the parent container.