A blank, rounded rectangle fills the entire browser viewport as the sole visual element. The piece demonstrates a minimalist SVG canvas setup using D3 v5, where the `d3.select` method targets the empty `<svg>` element and sets its dimensions to match the viewport's client width and height. A single `rect` is appended with a 40-pixel corner radius, creating a simple framed shape against the white background. The fixed-position CSS ensures the canvas remains stable within the browser window.