     <div class="collapse" id="menu-4" data-parent="#page-nav">
                    <div>
                      <ul class="nav flex-column">
                        <li class="nav-item">
                          <a class="nav-link" href="mvc.html#section-1">Domains</a>
                        </li>
                        <li class="nav-item">
                          <a class="nav-link" href="mvc.html#section-2">Controllers</a>
                        </li>
                      </ul>
                   