This example shows a minimal React application that renders the text “Hello React!” centered on the page. It demonstrates the basic structure of a React project using React 16.10.0 and ReactDOM, with the `ReactDOM.render` method mounting an `App` component into a `#root` div. The component is a simple functional component that returns a styled div with the message, and the styling is defined in an external CSS rule. The code is bundled into `bundle.js` for the browser to load.