<!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" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style type="text/css">
div{width: 500px;height: 100px;}
.box1{width: 100px;background: red; position: relative;top: 100px;left: 100px;}
.box2{background: green;}
.box3{background: blue;}
</style>
</head>
<body>
<!--positon:relative不改變文檔流：box2、box3不因box1的定位而受影響→→即box1原來的位置保留。-->
<div class="box1">box1</div>
<div class="box2">box2</div>
<div class="box3">box3</div>
</body>
</html>
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