A blank, rounded rectangle fills the entire browser window on a white background, creating a minimalist canvas with no data or marks. The visualization sets the SVG’s dimensions to match the viewport and draws a single `<rect>` with a corner radius of 40 pixels. It uses d3’s `select` to target the SVG element and sets its width and height via `document.body.clientWidth` and `clientHeight`, demonstrating a simple setup for an empty framing space.