<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<div onclick="GoTop();" style="width:50px;height:50px;background: white;
position:fixed;
bottom:20px;
right:20px;
">返回顶部</div>
<div style="height:5000px; background: #dddddd;"></div>
<Script>
function GoTop(){
document.body.scrollTop = 0;
}
</Script>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.pg-header{
height:48px;
background-color: black;
color:#dddddd;
position: fixed;
top:0;
right:0;
left:0;
}
.pg-body{
height:5000px;
background-color: #dddddd;
margin-top: 50px;
}
</style>
</head>
<body>
<div class="pg-header">头部</div>
<div class="pg-body">内容</div>
</body>
</html>