A smiling face built from SVG primitives is drawn with yellow head, hat, eyes, nose, and mouth. The React components (`Hat`, `Eye`, `Eyes`, `Nose`, `Mouth`) construct the scene, while D3's `arc` API generates the mouth path. The viewport is fixed at 600×480, and the SVG uses a 960×500 canvas with a translated group. Custom CSS classes style each facial feature, and the code imports `arc` from `d3` and uses ReactDOM to render the app.