This example shows a smiley face composed of SVG shapes, built with React components and D3’s arc generator. The background circle and eyes are rendered as JSX elements, while the mouth uses the `d3.arc()` API from `mouthArc.js` to define a path with inner and outer radii and angled endpoints. All shapes are centered via a translated `<g>` group inside a fixed-width SVG. The code separates reusable pieces like `BackgroundCircle` into distinct modules, combining React’s declarative structure with D3’s geometry helpers.