/*fixed定位：相对于浏览器窗口*/
position: fixed;
<html>
<head>
<meta charset="utf-8">
<title>绝对定位、相对定位</title>
<style>
#d{
width: 200px;
height: 200px;
background: red;
}
#d1{
width: 50px;
height: 50px;
background: yellow;
/*相对定位:相对于元素本身应该在的位置移动*/
position: relative;
left: 20px;
bottom: 20px;
}
#d2{
width: 50px;
height: 50px;
background: pink;
}
#dd{
width: 200px;
height: 200px;
background: blue;
position: relative;
}
#dd1{
width: 50px;
height: 50px;
background: orange;
left: 20px;
bottom: 20px;
/*绝对定位：距离父类（有position样式的父类）...body*/
position: absolute;
left: 20px;top: 50px;
z-index: 100;
}
#dd2{
width: 50px;
height: 50px;
background: grey;
position: absolute;
left: 30px;
top: 60px;
z-index: 50;
}
</style>
</head>
<body>
<div id="d">
<div id="d1"></div>
sadassafasf
<div id="d2"></div>
</div>
<div id="dd">
<div id="dd1"></div>
<div id="dd2"></div>
</div>
</body>
</html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
#d{
width: 200px;
height: 200px;
background: red;
/*fixed定位：相对于浏览器窗口*/
position: fixed;
left: 20px;
top: 50px;
}
</style>
</head>
<body>
<div id="d"></div>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
</body>
</html>
原文：https://www.cnblogs.com/boss-H/p/10645852.html