This example shows a React application that renders a simple message, “Hello React!”, centered on the page using large, bold text. It demonstrates how to set up a React component and mount it to the DOM via `ReactDOM.render`. The code uses `React` and `ReactDOM` from the UMD production builds loaded via CDN, with the app defined as a functional component returning a `<div>` element with a CSS class. No data source or external visualization library is used; the example only displays static text styled through the `message` class.