This example demonstrates how D3.js mask elements can selectively hide or reveal overlapping shapes, creating a geometric grid pattern of 100 horizontal and vertical rectangles. The visualization uses two SVG masks with inverted color schemes—one black with white symbols and one white with black symbols—to control visibility across the layers. It employs `d3.select`, `d3.range`, `d3.symbol`, and `d3.symbols` to generate and position the mask paths, while SVG rects and mask attributes handle the rendering. The code adapts automatically to the browser viewport dimensions.