npub19kdxqvj7x7lnkq7quf2x7795cdx6z000zknqfs4tzjmqejdcreusnv4jdw (npub19kd…4jdw)
Somewhere in the Spec: https://www.w3.org/TR/css-grid-1/#algo-overview
> Note: Since formulas calculated using only definite sizes, such as the stretch fit formula, are also definite, the size of a grid item which is stretched is also considered definite.