<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>编程狮(w3cschool.cn)</title>
<style>
.Absolute-Center {
width: 50%;
height: 50%;
overflow: auto;
margin: auto;
position: absolute;
top: 0; left: 0; bottom: 0; right: 0;
}
</style>
<body>
<div class="Absolute-Center">你好 w3cschool</div>
</body>