请问我这个左侧的垂直导航左边怎么有一段空
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Bootstrap 实例 - 默认的导航栏</title>
<link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>
<nav class="navbar navbar-inverse" role="navigation">
<div class="container-fluid">
<div class="navbar-header">
<a class="navbar-brand" href="#">菜鸟教程</a>
</div>
<div>
<ul class="nav navbar-nav">
<li class="active"><a href="#">iOS</a></li>
<li><a href="#">SVN</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">
Java
<b class="caret"></b>
</a>
<ul class="dropdown-menu">
<li><a href="#">jmeter</a></li>
<li><a href="#">EJB</a></li>
<li><a href="#">Jasper Report</a></li>
<li class="divider"></li>
<li><a href="#">分离的链接</a></li>
<li class="divider"></li>
<li><a href="#">另一个分离的链接</a></li>
</ul>
</li>
</ul>
<form class="navbar-form navbar-right" role="search">
<div class="form-group">
<input type="text" class="form-control" placeholder="Search">
<input type="text" class="form-control" placeholder="Search">
</div>
<button type="submit" class="btn btn-default">提交</button>
</form>
</div>
</div>
</div>
</nav>
<div class="container">
<div class="row">
<div class="col-lg-2 col-md-2">
<div class="container-fluid">
<ul class="nav nav-pills nav-stacked">
<li class="active"><a href="#">Home</a></li>
<li><a href="#">SVN</a></li>
<li><a href="#">iOS</a></li>
<li><a href="#">VB.Net</a></li>
<li><a href="#">Java</a></li>
<li><a href="#">PHP</a></li>
</ul>
</div>
</div>
<div class="col-lg-10 col-md-10">
<h1>控制管理台</h1>
<hr>
<button type="button" class="btn btn-default">默认按钮</button>
<button type="button" class="btn btn-primary">原始按钮</button>
<button type="button" class="btn btn-success">成功按钮</button>
<button type="button" class="btn btn-info">信息按钮</button>
<button type="button" class="btn btn-warning">警告按钮</button>
<button type="button" class="btn btn-danger">危险按钮</button>
<div class="container">
<div class="row">
<div class="col-md-6 col-lg-6">
</div>
<div class="col-lg-6 col-md-6">
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>