This example renders a full-window smiley face as an SVG graphic using React 16.9. It positions a yellow circle with a black outline, two eyes, and a mouth via SVG `<circle>` elements. The code computes dimensions from `window.innerWidth` and `window.innerHeight`, centering the face and scaling its radius based on viewport height. ReactDOM renders the component into the `root` element, with all geometry defined through constants like `eyeOffsetX` and `mouthRadius`.