4-3老师这样写可以吗

来源：4-3 编程练习

慕工程0065766

2018-07-17 21:49:38

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>position</title>
<style>

         {margin:0;
          padding:0;}

       .a{width:100%;
       height:4043px;
       background:url(http://climg.mukewang.com/59c9f7ce0001839219034033.png) top center no-repeat;}
       .b{width:224px;
         height:160px;
         background:url(http://climg.mukewang.com/5a3383c70001f1b702240364.png) top center no-repeat;
         position:fixed;
         left:0;
         top:50%;
         margin-top:-80px;}
         .c{width:224px;
         height:160px;
         background:url(http://climg.mukewang.com/5a3383d00001a3dd02240364.png) top center no-repeat;
         position:fixed;
         right:0;
         top:50%;
         margin-top:-80px;}

</style>
</head>
<body>