                        课程
                    
                        /前端开发
                        
                            /HTML/CSS
                        
                        /如何用CSS进行网页布局

main 不显示居中不管用为什么

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
body{margin::0;padding:0;}
.top{height:100px;backgrongd:blue;}/*宽度不定义，适应浏览器的通栏。*/
.main{width:800px;height:3oopx;background:#9F6;margin:0 auto;}
.foot{width:800px;height:100px;background:#FF0;margin:0 auto;}
</style>
</head>

<body>
<div class="top">
<p>nishuo</p>
</div>
<div class="main"></div>
<div class="foot"></div>
</body>
</html>