Use headline ID instead of class

web/app/templates/corpora/analyse_corpus.html.j2

@@ -361,7 +361,7 @@ document.addEventListener("DOMContentLoaded", () => {
   }
 
   // enable scroll to Top
-  scrollToTop('.headline', '#menu-scroll-to-top-div');
+  scrollToTop('#headline', '#menu-scroll-to-top-div');
 });
 </script>
 {% endblock %}

web/app/templates/nopaque.html.j2

@@ -231,7 +231,7 @@
         <div class="container">
         {% endif %}
         <div class="row">
-          <div class="col s12 headline">
+          <div class="col s12" id="headline">
             <h2>{{ headline }}</h2>
           </div>
           {{ insert_content() }}