This example shows a React-rendered smiley face that scales to fill the browser window. The face consists of a yellow circle with a black outline, two eye circles, and no mouth. It uses React and ReactDOM to create SVG elements, with the face centered using a `<g>` transform and dimensions calculated from `window.innerWidth` and `window.innerHeight`. The face’s size adapts dynamically to the viewport, and the code defines the props for each circle explicitly.