.left{background:blue;width:200px;height:190px;position:absolute;left:0;top:0; }在left選擇器中為什么用“left:0,top:0”來設置位置，而在right選擇器中用“margin-left”設置？
<!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>混合布局編程挑戰</title>
<style type="text/css">
body{ margin:0; padding:0; font-size:30px; color:#fff}
.top{background:#ccc;height:50px;}
.main{width:100%;background:red;height:190px;position:relative;}
.left{background:blue;width:200px;height:190px;position:absolute;left:0;top:0; }
.right{background:green;height:190px;margin-left:210px;}
.foot{background:orange;height:30px;}
</style>
</head>
<body>
<div class="top">top</div>
<div class="main">
??? <div class="right">right</div>
??? <div class="left">left</div>
</div>
<div class="foot">foot</div>
</body>
</html>
2016-03-18
右邊div不設寬度，要自適應。不設margin會自動跳到下一行，跟屏幕同寬