<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>浮动元素居中</title>
<style type="text/css">
<!--
#hezi {
position:absolute;
left:50%;
top: 50%;
}
.s_cell {
float:left;
position:relative;
right:50%;
bottom: 50%;
background: red;
}
-->
</style>
<meta http-equiv="Content-Type" content="text/html; charset=uft-8"></head>
<body>
<div id="hezi">
<div class="s_cell">
<span class="font_style">浮动元素内容1浮动元素内容1浮动元素内容1浮动元素内容1</span>
</div>
</div>
</body>
</html>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>子盒子绝对居中</title>
</head>
<style>
html,body{height: 100%;}
*{margin: 0px;padding: 0px;}
#big {
margin: 0 auto;
position: relative;
width: 100%;
height: 100%;
background: #5B5757;
}
.small {
width: 500px;
height: 200px;
position: absolute;
top: 50%;
left: 50%;
margin-left: -250px;
/*设置负值，为要定为子盒子的一半宽度*/
margin-top: -100px;
/*设置负值，为要定位子盒子的一半高度*/
background: green;
}
</style>
<div id="big">
<div class="small"></div>
</div>
</html>