This example renders a full-screen smiley face using React with SVG elements. It computes the width and height from `window.innerWidth` and `window.innerHeight`, centers the face at the middle of the screen, and draws a yellow circle with a black stroke as the head, plus two eyes positioned via `eyeOffsetX` and `eyeOffsetY`. The code uses React’s `createElement` and `ReactDOM.render` to mount the SVG dynamically, with the face scaling based on viewport dimensions.