This example renders a full-screen yellow smiley face using React and SVG. The face is centered on the window, with its radius determined by the viewport height, and includes black stroke outlines, two circular eyes, and a curved mouth. The code defines reusable constants for dimensions and positions, then constructs the SVG elements through React's JSX, using the `ReactDOM.render` API to mount the component into the DOM. It relies on the React 16.9 production build loaded via CDN.