鼠标过导航标签时，无效果，请问如何查找问题
<!DOCTYPE html>
<html>
<head>
<meat charset="utf-8">
<title>块级元素和行内元素相互转换</title>
<link rel="shortcut icon" type="image/x-icon" href="images/favicon.ico">
<style type="text/css">
p{display:inline;width:200px;height:200px;backgroud-color:#ccc;}
b{display:block;}
/*div{display:inline-block;height:30px;width:400px;background-color:pink;}*/
.box{width:100px;height:40px;background-color:#ccc;line-height: 40px;text-align: center;}
.main{width:100px;height:100px;background-color:pink;line-height:100px; text-align:center;display:none;}
.box:hover .main{display:block;}
</style>
</head>
<body>
<p>块级元素转为行内元素</p><span>123</span>
<b>行内元素主为块级元素</b>
<div>将标答转换为行内块元素</div><span>123</span>
<div class="box">导航</div>
<div class="main">小菜单</div>
</body>
</html>
