This example renders a generative geometric composition inspired by Sol LeWitt, using D3.js to create intersecting grids of thin horizontal and vertical rectangles. A circular mask, defined with SVG `mask` elements and `circle` shapes, reveals the grid pattern in the center while hiding it elsewhere. The code uses `select`, `range`, and `join` from D3 to efficiently generate and bind data to SVG `rect` elements, with the second mask inverting the visibility to produce a layered effect. The visualization fills the browser window and updates with the viewport size.