滑鼠過導航標籤時，無效果，請問如何找出問題
<!DOCTYPE html>
<html>
<head>
<meat charset="utf-8">
<title>區塊級元素與行內元素相互轉換</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>區塊級元素轉為行內元素</p><span>123</span>
<b>行內元素主為區塊級元素</b>
<div>將標答轉換為行內塊元素</div><span>123</span>
<div class="box">導航</div>
#<div class ="main">小選單</div>
</body>
</html>
