This example demonstrates a blank, responsive canvas that fills the entire browser window. The visualization is an empty SVG surface with a large rounded rectangle covering its full dimensions, creating a minimalist starting point. The code uses D3 v5's `select` function to target the SVG element, sets its width and height based on the viewport, and appends a `rect` with a corner radius of 40 pixels. The fixed positioning and hidden overflow in the CSS ensure the canvas remains stable and fully visible.