This example renders a full-screen, yellow smiley face using React and SVG. It draws a large circle for the head centered on the window, two smaller circles for eyes, and leaves space for a mouth that is not implemented. The code uses React’s `ReactDOM.render` to mount an `App` component that generates an `<svg>` with calculated dimensions from `window.innerWidth` and `window.innerHeight`. All shapes are positioned via a `<g>` transform, with fixed offsets for the eyes and a yellow fill with a black stroke.