NG: grid-column has no effect without display: grid on the parent
span 2 specified (not working)
Child 2
Child 3
OK: add display: grid to the parent first
span 2 specified (spans 2 columns)
Child 2
Child 3
NG: without grid-template-columns, everything stacks in one column
Child 1
Child 2
Child 3
OK: grid-template-columns creates horizontal columns
Child 1
Child 2
Child 3