Bootstrap Modal的模态内容未显示在传单地图上

Question

插入“ Where M I”按钮（Prova按钮）中的模态，单击该按钮后无法显示，该如何解决？是地图问题还是只需要一些js解决？

<nav class="navbar navbar-expand-lg navbar-light bg-light">
 <a id="simbolo" href="#"><i class="material-icons">my_location &nbsp;</i></a>
 <div class="dropdown">
  <a class="btn btn-link dropdown-toggle navbar-brand" href="#" role="button" id="dropdownMenuLink"
    data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" style="font-size: 150%">
    Where M I?
  </a>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuLink">
    <!-- Button trigger modal -->
    <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
      Prova
    </button>

    <!-- Modal -->
    <div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel"
      aria-hidden="true">
      <div class="modal-dialog" role="document">
        <div class="modal-content">
          <div class="modal-header">
            <h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
            <button type="button" class="close" data-dismiss="modal" aria-label="Close">
              <span aria-hidden="true">&times;</span>
            </button>
          </div>
          <div class="modal-body">
            <p>Prova</p>
          </div>
          <div class="modal-footer">
            <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
            <button type="button" class="btn btn-primary">Save changes</button>
          </div>
        </div>
      </div>
    </div>
    <hr>
    <a class="dropdown-item" href="#">Playlist Audio</a>
    <hr>
    <a class="dropdown-item" href="#">Playlist Video</a>
    <hr style="margin-bottom: 10%">
    <a class="dropdown-item" href="./about.html"><small>About</small></a>
  </div>
</div>
</nav>

这是我的完整代码： https://codepen.io/anon/pen/WVZyEb#anon-signup