This example shows a customizable smiley face built from modular React components, with a yellow circular background, two black eyes, and a curved mouth drawn using the D3 arc generator. The face is centered within an SVG via a transformed group, and all dimensions—such as eye offset, eye radius, mouth radius, and stroke width—are passed as props from the main App component. React 16.9 and D3 v5 handle the rendering, with the mouth path computed by `d3.arc` using specified inner and outer radii and angular ranges. The code demonstrates composing reusable SVG elements through React’s component architecture.