<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{margin: 0;padding: 0;}
.box{
width: 500px;
height: 400px;
background:red;
margin: 200px;
position: relative;
}
.con{
width: 100px;
height: 100px;
background: pink;
position: absolute;
top:0px;
bottom:0px;
left:0px;
right:0px;
margin:auto;
}
.box1{
width: 500px;
height: 400px;
background:red;
margin: 200px;
position:relative;
}
.con1{
width: 100px;
height: 100px;
background:pink;
position:absolute;
top:50%;
left:50%;
margin-left:-50px;
margin-top:-50px;
}
</style>
</head>
<body>
<div class="con"></div>
</body>
</html>
