<div class =“nav-collapse collapse”>链接未显示。一个月的Rails课程</div>

Question

我正在研究One Month Rails课程并且遇到了障碍。我正在观看＆＃34;添加Bootstrap＆＃34;我正在尝试将导航栏添加到页面顶部。当我添加代码时，Home＆amp;关于链接消失。请查看代码并让我知道是否有任何错误，如果其他文件夹中有其他错误，那么它是否也可能是Bootrap的版本？

<div class="navbar">
  <div class="navbar-inner">
    <div class="container">

      <!-- .btn-navbar is used as the toggle for collapsed navbar content -->
      <a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </a>

      <!-- Be sure to leave the brand out there if you want it shown -->
      <a class="brand" href="#">Project name</a>

      <!-- Everything you want hidden at 940px or less, place within here -->
      <div class="nav-collapse collapse">
        <ul class="nav">
            <li><%= link_to "Home", root_path %></li>
            <li><%= link_to "About", about_path %></li>
        </ul>
        <ul class="nav pull-right">
                <li><%= link_to 'Login', '#' %></li>
        </ul>
      </div>

    </div>
  </div>
</div>