This example demonstrates a minimal React application that renders a "Hello React!" message to the page. It uses React 16.9.0 and ReactDOM to mount a single `App` component into a `#root` element. The code imports React and ReactDOM directly, defines the component as a simple function, and calls `ReactDOM.render` to display it. This starter serves as a baseline for building more complex React-based visualizations, with styling set to remove default body margins and hide overflow.