此代码无法正确格式化，标签为2 cols宽，输入为10 cols宽。
我是初学者，我不确定是什么问题。请帮忙
<!DOCTYPE html>
<html>
<head>
<link rel='stylesheet' href='/stylesheets/style.css'>
<link rel='stylesheet' href="/bootstrap/css/bootstrap.min.css" media="screen">
</head>
<body>
<script src='//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js'></script>
<script src="/bootstrap/js/bootstrap.min.js"></script>
<form class="form-horizontal" role="form" method="POST" action="/addPerson">
<div class="form-group">
<label for="name_first" class="col-sm-2 control-label">First:</label>
<div class="col-sm-10">
<input class="form-control"
id="name_first"
type="text"
placeholder="First Name"
required/>
</div>
</div>
</form>
</body>
</html>
