This example renders a cartoon face composed of SVG shapes in a React component hierarchy. It uses D3's `arc` generator to draw the mouth and passes numeric props from a top-level `Face` component down to `BackgroundCircle`, `Eyes`, and `Mouth`. The face is centered with a yellow background circle, two black eyes, and a curved smile. The React app mounts to a div and renders the face into an SVG container with a fixed width and height.