A web page displays a grid of horizontal and vertical black bars overlaid with two circular SVG masks, creating a crosshatch pattern that is visible only within two intersecting circular regions. Using React 18 and D3's `select` and `range`, the code appends an SVG canvas sized to the viewport and generates 100 rectangles in each orientation. The masks, defined via `svg.append('mask')`, combine white and black circles to control visibility, producing a stark geometric composition centered on the screen.