position(fixed)--定位

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>position_ example</title>
    <style>
        .div1{
            height:1500px;
            background-color:green;
        }
        .div2{
            height:1500px;
            background-color:red;
        }
        a{
            position: fixed;
            right:20px;
            bottom:20px;
        }
    </style>
</head>
<body>
<div class="div1"><a>return top</a></div><!--return top put in tag div also-->
<div class="div2"></div>
<!--<a>return top</a>-->
</body>
</html>
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原文地址：https://www.cnblogs.com/startl/p/12177929.html