This example draws a classic smiley face using React and D3’s `arc` generator to create the mouth path. The SVG renders a yellow circle with black stroke, two eye pairs (black outer and white inner circles), and a red nose positioned at the center. All shapes are placed inside a `<g>` transform for offset, with coordinates computed from fixed dimensions. The code uses React components for the background circle and ReactDOM to mount the app to a `#root` element.