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<html> <head> <meta charset="UTF-8"> <title></title> <style type="text/css"> .divWrap{ width: 500px; height: 800px; background: red; margin: 20px auto; position: relative; } .div{ position: absolute; width: 30%; height: 30%; margin: auto; top: 0; left: 0; bottom: 0; right: 0; background: green; } </style> </head> <body> <div class="divWrap"> <div class="div"> </div> </div> </body></html>