This example renders a yellow smiley face as a full-screen SVG graphic using React. It computes dimensions from `window.innerWidth` and `window.innerHeight`, centers the face with a `g` transform, and draws a large circle for the head plus two eye circles. The code uses React 16.9.0 via UMD builds and ReactDOM for mounting to the `#root` element, with explicit constants for eye offset, eye radius, and stroke width. The mouth is not drawn.