This example demonstrates a bare minimum HTML page that renders static text and a dynamically inserted message using vanilla JavaScript. The page structure is defined in `index.html`, with `style.css` applying centered, large-scale typography. The JavaScript file `app.js` uses `document.getElementById('app')` to select a div element and sets its `innerHTML` property to display the text "Ok geht doch gut". No external libraries are used; the example solely relies on core HTML, CSS, and JavaScript APIs to show basic DOM manipulation and styling.