This example renders a full-screen smiley face using React and SVG. The face consists of a yellow circle with a black stroke, two black eyes positioned symmetrically around the center, and no mouth, as the code only defines the face and eye circles. The SVG width and height are set to the browser window dimensions, with the face centered via a translation transform. The React component uses JSX to create the SVG elements, and ReactDOM renders the app into the root div. The eye positions and radii are computed from the viewport size.