Twitter引导程序导航栏在移动设备/平板电脑上自动扩展

Question

我正在使用Twitter Bootstrap。它工作得很好，导航栏运行良好。它具有响应性并相应地进行调整，但是当您在桌面上缩小屏幕或者在移动电话上拉起网站时，它开始扩展已经占用了一大堆屏幕。我希望它可以通过扩展选项开始折叠。

代码如下：

<div class="navbar navbar-fixed-top">
 <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>
    <span class="icon-bar"></span>
    <span class="icon-bar"></span>
    <span class="icon-bar"></span>
    </a>

    <a class="brand" href="/">My Site</a>
     <div class="nav-collapse collapse">
    <ul class="nav">

      <li <% if @league=='recruiting' %>class="active"<% end %>><%= link_to "Recruiting", :controller => "league", :action=>"index", :league=>"recruiting" %></li>
      <li <% if @league=='college' %>class="active"<% end %>><%= link_to "College", :controller => "league", :action=>"index", :league=>"college" %></li>
      <li <% if @league=='nfl' %>class="active"<% end %>><%= link_to "NFL", :controller => "league", :action=>"index", :league=>"nfl" %></li>

    </ul>


     <ul class="nav pull-right">
        <li><a href="/blog">Blog</a></li>
        <li <% if params[:controller]=='chart' %> class="active"<% end %>><a href="/data/all/hundred">Data</a></li>
        <% if user_signed_in? %>
            <li><%= link_to "My Profile", user_profile_path(:username => current_user.username) %></li><li><%= link_to('Logout', destroy_user_session_path, :method => :delete) %></li>
        <% else %>
            <li><%= link_to "Login", "#login-lightbox", 'data-toggle'=>"modal", 'id'=>'login-link' %></li>
        <% end %>
     </ul>
    </div>
    </div>
  </div>
</div>