This example demonstrates a minimal React application that renders a static “Hello React!” message inside a root `<div>` element. It uses React 16.9.0 and ReactDOM, both loaded via UMD builds from unpkg, with the component defined as a simple functional arrow function. The application is mounted by calling `ReactDOM.render()` on the `<App />` component, targeting the `#root` DOM node. No data visualization logic is present; it solely serves as a starter template for integrating React into a gallery environment.