This example renders two alternating grids of horizontal and vertical bars, each masked by different geometric symbols to create a layered composition. Using React with D3 v7, it generates SVG rectangles based on window dimensions and applies SVG masks containing D3’s built-in symbol shapes. The code defines a `renderMask` function that creates white or black mask backgrounds with inverted symbol fills, then applies these masks to the bar groups. The visualization demonstrates how D3 selections, data joins, and mask operations combine multiple images into a single viewport.