This example demonstrates a minimal React application that renders a static message, “Hello React!”, centered on the page. The app component is defined inline using React’s JSX syntax and is mounted into the DOM via `ReactDOM.render`. The page loads React and ReactDOM from CDN links in `index.html`, while the core application logic resides in `index.js`. The styling is applied through a CSS rule targeting the `.message` class, showcasing a basic React setup without any data processing or interaction.