This example builds a stylized smiley face from modular SVG components, with a yellow circular background, two eyes, and a curved mouth. The face is composed using React components such as `BackgroundCircle`, `Eyes`, and `Mouth`, which are assembled inside a `FaceContainer` SVG group. The mouth is generated with the `d3.arc()` API, using a specified radius and width to create a semi-circular path. The rendering uses React and D3 v7, with all elements drawn in SVG.