A blank, rounded-rectangle canvas fills the entire browser viewport, with its width and height set to the document’s client dimensions. The example demonstrates a minimal SVG setup using D3 v5, where the `select` and `arc` functions are imported but only `select` is used to append a single styled `<rect>`. The visualization shows no data or interaction, serving purely as an empty starting point. It relies on the D3 selection API and SVG attributes, with CSS fixed positioning to prevent page scrolling.