This example renders a full-screen smiley face using React and SVG. It draws a yellow circle with a black stroke as the face, then places two smaller circles for eyes at fixed offsets from the center. The SVG is generated declaratively through React components, with dimensions and positions calculated from `window.innerWidth` and `window.innerHeight`. The code uses React’s `ReactDOM.render` to mount the SVG into the DOM, and the face scales to fit the viewport height.