col 1→4
row auto

col 5→8
row auto

col 9→12
row auto

col 1→6
row auto

col 7→12
row auto

z:0 BACKGROUND — col 1→12, row_start:3, row_span:2

z-index overlay works ✓

This text is col 2→9, row_start:3 z:1 — sitting above the dark bg block

z:2 TOP
CTA — row 4, col 2→5

← col 2-5 · This is col 6→11, row_start:4, z:1