This blank Canvas.js example uses D3 v6 to create a full-window, rounded-rectangle canvas. It selects the SVG element, sets its dimensions to the browser viewport, and appends a single rectangle covering the entire area. The code relies on D3’s `select` and `attr` APIs, with the rectangle’s corner radius set via the `rx` attribute. No data or interaction is present; the visualization merely demonstrates a minimal setup for a fixed, frameless plotting surface using the body’s CSS to fill the screen.