This visualization presents a blank, rounded rectangle filling the entire viewport, sized to match the browser window’s dimensions. The example serves as a minimal D3.js canvas setup, demonstrating how to establish an SVG coordinate space that adapts to the screen. Built with D3 v5, the code uses the `select` function to target the SVG element and `append` to add the rectangle shape. The fixed CSS positioning and hidden overflow ensure the canvas remains flush with the viewport edges, creating a pure foundation for subsequent drawing operations.