Fraction Wars

grid-template-columns: 1fr 1fr 1fr

Pick a track strategy

Resize the container and switch templates. See which layouts adapt gracefully.

Rule: fixed tracks are calculated first. fr divides whatever space is left.

Stage

grid-template-columns: 1fr 1fr 1fr
Column AContent block
Column BContent block
Column CContent block
ExtraAuto-placement continues
ExtraGrid keeps flowing
ExtraUntil you take control

Pixels define. Fractions adapt.