Wrapped nav items in a container element

index.html

@@ -29,6 +29,7 @@
 
     <!-- Navigation -->
     <nav class="navbar navbar-expand-lg navbar-dark fixed-top" id="mainNav">
+      <div class="container">
         <a class="navbar-brand" href="#page-top">Start Bootstrap</a>
         <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarResponsive" aria-controls="navbarResponsive" aria-expanded="false" aria-label="Toggle navigation">
           Menu
@@ -53,6 +54,7 @@
             </li>
           </ul>
         </div>
+      </div>
     </nav>
 
     <!-- Header -->