This example demonstrates a completely blank SVG canvas that scales to fill the browser window. The code uses D3 v5’s `select` method to target the SVG element, then sets its width and height based on the viewport dimensions. A single rectangle with rounded corners (`rx` set to 40) fills the entire space, styled by the accompanying CSS, which fixes the body to the viewport and removes margins. The visualization serves as a minimal starting point for any future D3 project.