A full-screen yellow smiley face, drawn with black outlines, is rendered across the entire browser viewport. The face dynamically centers itself and scales its radius relative to the window’s height, while the eyes and mouth are positioned at fixed offsets from the center. Built with React and react-dom, the example uses SVG circle elements within a transformed group. The code explicitly references `window.innerWidth` and `window.innerHeight` to set the canvas size, and it uses `ReactDOM.render` to insert the component into the page.