Insert the following HTML code into your file. You can customize it to your liking using Bootstrap, Tailwind or simply CSS.

<!-- Datei-Upload -->
<div class="mb-4">
    <label for="csvFileInput" class="block text-lg font-semibold">CSV-Datei auswählen:</label>
    <input type="file" id="csvFileInput" accept=".csv" class="mt-2 p-2 border rounded bg-white shadow">
</div>

<!-- Konvertieren Button -->
<button onclick="convertCSVtoJSON()" class="bg-blue-500 hover:bg-blue-600 text-white font-bold py-2 px-4 rounded shadow mb-4">
    CSV in JSON konvertieren
</button>

<!-- JSON-Download Button -->
<button onclick="downloadJSON()" id="jsonDownloadButton" class="bg-green-500 hover:bg-green-600 text-white font-bold py-2 px-4 rounded shadow mb-4" disabled>
    JSON herunterladen
</button>

<!-- JSON-Ausgabe -->
<pre id="output" class="mt-4 p-4 bg-white rounded shadow overflow-auto max-h-96"></pre>