错在那里？
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<title></title>
<style>
div {
width: 100px;
height: 90px;
float: left;
padding: 5px;
margin: 5px;
background-color: #EEEEEE;
}
</style>
<script src="http://libs.baidu.com/jquery/1.9.1/jquery.js"></script>
</head>
<body>
<div id="aaron">
<p>id="aaron"</p>
<p>选中</p>
</div>
<div id="imooc">
<p>id="imooc"</p>
<p>jQuery选中</p>
</div>
<div class="imooc">
<p>class="imooc"</p>
<p>jQuery未选中</p>
</div>
<div class="imooc">
<p>class="imooc"</p>
<p>jQuery未选中</p>
</div>
<div class="imooc">
<p>class="imooc"</p>
<p>jQuery未选中</p>
</div>
<script type="text/javascript">
//通过原生方法处理
var div = document.getElementById('aaron');
div.style.border = "3px solid blue";
</script>
<script type="text/javascript">
//通过jQuery直接传入id
//id的唯一，只选择到了第一个匹配的id为imooc的div节点
$("#imooc").css("border", "3px solid red");
$('.imooc').css('border'.'3px solid yellow');
</script>
</body>
</html>
