Added main-tag

Semantic tags improve accessibility for screenreader-users.

radicale/web/internal_data/index.html

@@ -21,6 +21,7 @@
     </ul>
 </nav>
 
+<main>
 <section id="loadingscene">
     <h1>Loading</h1>
     <p>Please wait...</p>
@@ -131,6 +132,7 @@
         <button type="button" data-name="cancel">No</button>
     </form>
 </section>
+</main>
 </body>
 
 </html>