This example renders a full-screen smiley face using React and D3, centered within an SVG canvas sized to the browser window. The face consists of reusable components: a yellow background circle with a black stroke, two eyes positioned symmetrically, and a mouth drawn with a D3 arc path. A polygon forms a nose above the mouth. The layout positions all features relative to the window center, with radii and offsets calculated dynamically from the viewport height.