This example renders a stylized smiley face using SVG, built with React and D3. The code defines a yellow circle with a black stroke as the head, positions two small circles for eyes, and uses `d3.arc()` to create a mouth arc with specified inner and outer radii and angle parameters. It employs ReactDOM to render the SVG into a `#root` div, with all geometry computed from width, height, and offset constants. The drawing is entirely programmatic, generated from numeric values rather than external data.