This example shows a React component rendering a single, large “Hello D3 & React” message centered on the page. It demonstrates the minimal integration between React and D3 by using the `useRef` and `useEffect` hooks to access a DOM node, then calling `d3.select` from D3 v7 to set the text content. The app is mounted with `createRoot` from `react-dom/client`, and React 19 is loaded via an import map. The code contains no data sources or complex visualizations, focusing purely on the starter setup.