This example renders a single large circle inside an SVG canvas. The visualization uses D3’s selection API to append a circle element to an existing `<svg>` tag and sets its radius to 200 pixels. The circle occupies most of the 690×500 pixel viewport, with the page margin removed via CSS for a full-bleed display. React manages the DOM container, while the direct SVG manipulation happens through D3’s `select` and `append` methods. The data source is minimal, showing a static geometric shape rather than a dynamic dataset.