Smiley Face
A yellow smiley face rendered with React and D3 occupies a fixed 960 by 500 SVG canvas. The code builds the face manually using SVG circles for the head and eyes, and a D3 arc generator (`arc()`) with a `path` element to create the mouth. The face is centered with a group transform, and React manages the component structure using JSX. The example demonstrates simple, declarative SVG composition within a React component, using D3 solely for generating the arc path data.