v156 · scroll-snap-type: pair · geometry & N²−N analysis

Diagonal gallery & phantom-intersection inspector

When a 2D scroll container holds N staggered items at distinct coordinates (X_i, Y_i), scroll-snap-type: both evaluates X and Y independently — creating N × N = N² total snap targets, of which N² − N are empty phantom intersections (X_i, Y_j) where i ≠ j. With scroll-snap-type: pair, only the N real element pairs exist.