This example displays a large, centered “Hello React!” message in a full-page browser view. It demonstrates a minimal React application by rendering a single component into the document’s root element. The code imports React and ReactDOM, defines a functional `App` component that returns a styled `<div>`, and calls `ReactDOM.render` to mount it. The styling is applied through a CSS class defined in the accompanying HTML file, and the bundle is loaded via a separate `bundle.js` script.