2_columns_50_50 — left half
colPos 0, span 6 → 510px. Two equal halves: 510 + 60 gutter + 510 = 1080.
Right half
colPos 2, span 6 → 510px.
colPos 0, span 6 → 510px. Two equal halves: 510 + 60 gutter + 510 = 1080.
colPos 2, span 6 → 510px.