;-)

www/index.html

@@ -109,7 +109,7 @@
         <div class="modal-dialog modal-xl modal-dialog-centered" role="document">
           <div class="modal-content">
             <div class="modal-header">
-              <div class="modal-title">Document</div>
+              <h5 class="modal-title">Document</h5>
               <div class="col align-self-center">
                 <div class="btn-group" role="group" aria-label="Basic example">
                   <button type="button" class="btn btn-secondary">S</button>