This example displays a blank canvas that fills the entire browser viewport. The visualization uses a simple SVG rectangle with rounded corners, rendered in a fixed-position body that prevents scrolling. The code relies on D3 v5's selection API (`select`) to target the SVG element and sets its dimensions based on the document's `clientWidth` and `clientHeight` properties. The rectangle’s `rx` attribute gives it a subtle rounded appearance, creating an empty but intentional visual space.