This example renders 100 horizontal rectangles that span the full window width, each stacked at 20-pixel intervals. The rectangles are drawn as SVG elements using D3’s `select`, `join`, and attribute setters, with a `mask` attribute referencing a `circle-mask` defined elsewhere. Data is generated programmatically via `Array.from`, mapping index values to `y` positions and fixed widths and heights. The code demonstrates a minimal React-free workflow, appending an SVG to the body and sizing it to `window.innerWidth` and `window.innerHeight`.