This example creates a grid of horizontal and vertical stripes whose visibility is selectively revealed through two SVG masks, positioned over symbol-shaped cutouts. The mask pattern is generated using D3’s `range` and `symbol` APIs, alternating between normal and inverted masks to produce a complementary crossover effect. The visualization renders entirely with SVG, using dynamic `mask` URLs applied to each rectangle. The code leverages D3 v7 selections, joins, and the `symbol` generator to construct geometric shapes across the full viewport.