A blank, interactive canvas fills the browser window, rendered as a single rounded rectangle sized to the full viewport. The visualization demonstrates a minimal SVG setup using D3 v5, where the `select` function targets the empty `<svg>` element and dynamically sets its width and height attributes based on `document.body.clientWidth` and `clientHeight`. A single `<rect>` is appended and styled with a corner radius of 40 pixels. No data is loaded or transformed; the piece exists purely as a static starting point for further layering.