This example displays a large, centered "Hello React!" message as a static text visualization. It demonstrates the fundamental pattern of a React application by defining an `App` component that renders a `div` with a CSS class, then mounting it to the DOM root via `ReactDOM.render`. The code imports `React` and `ReactDOM` directly from the React 16.10.0 UMD builds and uses JSX syntax inside the component. The styling, including the font size and text alignment, is applied through a global CSS rule in the HTML file.