This example displays the text “Hello React!” centered in large type on a plain white background. It shows how React renders a single functional component into a DOM node. The code uses React and ReactDOM from the UMD production builds, defining an `App` component that returns a `<div>` with a CSS class controlling font size and alignment. The `ReactDOM.render` method mounts the component to the `#root` element. No data source or interaction is present, serving as a minimal starter template.