A grid of 16 by 8 rounded rectangles displays a random pattern of purple and yellow cells, where each cell’s color is determined by a Boolean value from `Math.random()`. The React components `CellMatrix` and `Cell` position each rect using computed `x` and `y` offsets based on the inner dimensions, while the `VizContainer` renders the SVG output with configurable margins and a neutral gray background. This example uses plain React state-free rendering, with no D3 API calls beyond the library’s inclusion in the HTML page.