A minimal web application renders the text “Hello React!” to the browser. The example combines React 17, ReactDOM, and D3 6.6 to demonstrate a basic setup. The `index.html` file loads these libraries from a content delivery network, while `index.js` imports React and ReactDOM, defines a simple arrow function component, and uses `ReactDOM.render` to mount it to the `#root` element. The page includes custom CSS to remove body margins and hide overflow.