This example shows a yellow smiley face rendered as a scalable SVG, with the face centered and sized to fill the browser window. The face includes a circular head, two eyes, and a mouth, all constructed from basic SVG primitives. The implementation uses React 16.9.0 with ReactDOM to render the SVG elements dynamically, computing the center coordinates and dimensions from `window.innerWidth` and `window.innerHeight`. The code defines constants for eye offset, eye radius, mouth width, and mouth radius, though the mouth itself is not drawn in the visible output.