This example builds a data-driven face using React and SVG primitives. It composes a yellow circular background, two eyes, and an arc-based mouth into a reusable `Face` component. The `Mouth` component uses `d3.arc` to generate a path, while a separate SVG tracks mouse movement, drawing a red circle that follows the cursor. The app renders via `ReactDOM.render`, with all geometry defined by explicit parameters like `eyeOffsetX` and `mouthRadius`.