Smily Face Part I
This example renders a yellow smiley face using React and D3.js. It draws the face with SVG circles for the head, eyes, and mouth, all positioned relative to the center of a 960x500 canvas. The mouth uses D3's `arc` generator to create a path, while the head and eyes are plain SVG circle elements. The code sets explicit `strokeWidth`, `eyeOffset`, and `eyeRadius` constants to control the composition.