当我在Mac上缩小窗口时，会出现汉堡菜单，但在移动设备上却没有。导航栏变得非常无格式。任何帮助将不胜感激。谢谢！
<nav class="navbar navbar-inverse">
<div class="container">
<div class = "row">
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
</button>
</div>
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li><%= link_to "HomePage", listings_path %></li>
<li><%= link_to "Reviews", reviews_path %> </li>
<li><%= link_to "My Personal Listings", mylistings_path %></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Admin<span class="caret"></span></a>
<ul class="dropdown-menu">
<%if user_signed_in? && current_user.admin? %>
<li><%= link_to "Admin Page", users_path %></li>
<li><%= link_to "Add a Personal Listing", new_mylisting_path %></li>
<%end%>
</ul>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Your Account <span class="caret"></span></a>
<ul class="dropdown-menu">
<li><%= link_to 'Sign In', new_user_session_path %></li>
<li><%= link_to 'Sign Up', new_user_registration_path %></li>
<li><%= link_to('Sign Out', destroy_user_session_path, :method => :delete) %></li>
</ul>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Additional Resources<span class="caret"></span></a>
<ul class="dropdown-menu">
<li><%= link_to 'Zillow', "http://www.zillow.com/", :target => "_blank"%></li>
<li><%= link_to 'Realtor.com', "https://www.realtor.com/", :target => "_blank"%></li>
<li><%= link_to "Multiple Listing Service", "http://www.mls.com/", :target => "_blank"%></li>
<li><%= link_to 'Trulia', "https://www.trulia.com/", :target => "_blank"%></li>
<li><%= link_to 'Redfin', "https://www.redfin.com/", :target => "_blank"%></li>
</ul>
</li>
</ul>
</div>
</div>
</div>
</nav>