# Flex Grid: Unstack and Block Grid

The top-level row has the class `.medium-unstack`, which means child columns stack on small, and sit side-by-side on medium screens and up.

The nested row has the class `.up-3`, which means its columns are 33% width no matter the screen size.

These two features should not interact. The two top-level columns always stack on small, and the three nested columns always stay the exact same percentage width.

Column One
Block Grid Column One
Block Grid Column Two
Block Grid Column Three
Column Two