This example reproduces a Sol LeWitt-inspired geometric composition using D3 v6. It displays a grid of horizontal and vertical lines that remain visible only within two circular regions, creating a layered visual effect through masking. The code uses `d3.select` to create SVG elements and `d3.range` with `join('rect')` to generate 100 line strips in each direction. Two SVG masks (`circle-mask` and `circle-mask-2`) alternate black and white fills to reveal or hide the lines within the circles, all rendered with dynamic window dimensions.