设置position：fiexd之后
不设置top,bottom,left,right位置样式,
通过margin间接调整
复制代码就是开干
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>Document</title>
<style>
.father {
width:300px;
height:300px;
margin-top: 200px;
margin-left: 200px;
background:green;
}
.son {
position:fixed;
margin-top: 140px;
width:150px;
height:150px;
background:red;
word-break: break-all;
}
</style>
</head>
<body>
<div class="father">
<div class="son">
son
</div>
</div>
<p style="height:10000px"></p>
</body>
</html>