This example demonstrates how SVG masks can create intersecting geometric patterns. Two sets of thin, full-length rectangles—horizontal and vertical—are drawn across the entire viewport using d3.range and d3.selectAll. Each set applies a different circular mask: one reveals a white circle against a black background, while the other inverts the mask, hiding the circle. The result is a crosshatched grid with a central circular region where the two masked layers visibly interact. The code uses D3 v6 selections and the SVG `<mask>` element.