An empty, rounded-rectangle SVG canvas fills the entire browser viewport. The example demonstrates a minimal D3 v5 setup where the `select` and `arc` functions are imported but unused, leaving the visualization intentionally blank. The code sets the SVG’s width and height attributes based on `document.body.clientWidth` and `clientHeight`, then appends a single `rect` with a 40-pixel corner radius. No data or interaction is present, showing the starting point for a blank visualization project.