This example creates a blank, rounded rectangle that fills the entire browser window, providing a simple, empty SVG canvas. The visualization uses the d3.select API to target the SVG element and dynamically sets its width and height based on the current document body dimensions. A single rectangle is appended and styled with a 40-pixel corner radius, while CSS positions the body to cover the viewport with hidden overflow. The result is a minimal, functional starting point for further D3 development, rendered entirely through vector graphics.