index.html

<div class="collapse navbar-collapse" id="navbarSupportedContent">
  <ul class="navbar-nav mr-auto">
    <li class="nav-item active" data-route="#">
      <a class="nav-link" href="#">Home</a>
    </li>
    <li class="nav-item active" data-route="#">
      <a class="nav-link" href="#">Messages</a>
    </li>
    <li class="nav-item active" data-route="#">
      <a class="nav-link" href="#">Notifications</a>
    </li>
  </ul>
  <form class="form-inline">
    <button class="btn my-2 my-sm-0" data-toggle="modal" data-target="#loginModal" type="button" id="loginModalBtn">Login</button>&nbsp;
    <button class="btn btn-outline-danger d-none" id="logoutBtn">Logout</button>
  </form>
</div>