Main Smiley
A stylized smiley face rendered as an SVG using React components, with D3’s `arc` generator drawing the mouth. The face is composed of reusable pieces—a yellow background circle, two dark eyes with white highlights, and an arc-based smile—all positioned relative to a central coordinate system. React props control geometry like eye offset, radius, and stroke width, while the D3 arc’s `innerRadius`, `outerRadius`, and start/end angles define the mouth’s curvature. The final shape is assembled through nested React components and mounted into the DOM via ReactDOM.