Two sets of 100 striped rectangles overlay each other at right angles, revealing a circular window at the center through SVG masks. Built with d3.select and d3.range, the code generates horizontal and vertical bars filled with alternating colors. Each set applies a mask combining a full-screen rect with a 200-pixel-radius circle, one using a white circle on black and the other inverting the colors. The result forms a crosshatched grid visible only inside the overlapping circular region, rendered as vector SVG graphics scaled to the full browser viewport.