React Starter
A React starter example renders a static "Hello React!" message centered on the page using a large font size. The code imports React and ReactDOM, defines a functional component that returns a div with a CSS class, and mounts it to a root element via `ReactDOM.render`. The HTML loads React and ReactDOM from unpkg CDN, while the bundled JavaScript is built with webpack and Babel, as indicated by the `bundle.js` reference.