A full-screen blank canvas is rendered as a single rounded rectangle filling the browser viewport. The example demonstrates minimal SVG setup with D3 v5, using `d3.select` to size the `<svg>` element to the document body’s dimensions and appending one `rect`. The code relies on `document.body.clientWidth` and `clientHeight` for sizing, while static CSS positions the body to prevent scrolling. No data or interaction is shown; the piece simply presents an empty, neutral space ready for further visualization work.