This example presents a minimal React application that renders a static message to the browser. It shows the text “Hello React!” centered on the page with a large font size, demonstrating the basic structure of a React project. The code uses `ReactDOM.render` from the `react-dom` library to mount an `App` component that returns a `<div>` with a CSS class, onto the `#root` element in the HTML. The page loads React and ReactDOM via UMD scripts from unpkg, and the styling is defined in an inline style block within the HTML.