<nav class="navbar navbar-default navbar-inverse navbar-fixed-top"> //navbar-inverse 設置背景                                                        //navbar-fixed-top 設置頭部固定在頂部,因此需要給body設置頂部padding,一般設置為padding-top:60px <div class="Container-fluid"> //container-fluid設置導航條內容是否有一定的內間距,如果class="container-fluid"則沒有內間距,內容緊貼左側        //如果設置class="container",則內容有一定的內間距,內容對稱居中  <!-- Brand and toggle get grouped for better mobile display -->  <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>    <span class="icon-bar"></span>    <span class="icon-bar"></span>   </button>   //這里是響應式的寫法,在小屏幕上回顯示三桿,無需改動   <a class="navbar-brand" href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >某管理系統</a>  </div>  <!-- Collect the nav links, forms, and other content for toggling -->  <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">   <ul class="nav navbar-nav">    <li class="active"><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >首頁 <span class="sr-only">(current)</span></a></li>    <li class="dropdown">     <a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">功能 <span class="caret"></span></a>     <ul class="dropdown-menu">      <li class="dropdown-header" >業務功能</li>      <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >信息建立</a></li>      <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >信息查詢</a></li>      <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >信息管理</a></li>      <li role="separator" class="divider"></li>      <li class="dropdown-header" >系統功能</li>      <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >設置</a></li>      <li role="separator" class="divider"></li>     </ul>    </li>    <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >幫助</a></li>   </ul>   <form class="navbar-form navbar-left pull-right">    <div class="form-group">     <input type="text" class="form-control" placeholder="username...">     <input type="password" class="form-control" placeholder="password...">    </div>    <button type="submit" class="btn btn-default">Login</button>   </form>  </div><!-- /.navbar-collapse --> </div><!-- /.container-fluid --></nav>