未知长宽元素在已知300px*300px的容器中垂直居（IE6/7/8/FF）
上次电话面试没答出来，今天重新记录一下。FF下的确难搞...郁闷
加了很多HACK，顺便复习一下！
*+property:value; /* IE7 */
_property:value; /* IE6 */
*property:value; /*IE6、IE7 共用*/
<!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>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>IE6/7/8/FF垂直居中</title>
<style>
* { margin:0; padding:0; }
#out { display:table; background-color:#F00; width:300px; height:300px; _position:relative; overflow:hidden; }
#mid { vertical-align:middle; display:table-cell; _position:absolute; _top:50%; -left:50%; }
#in { _position:relative; _top:-50%; _left:-50%; text-align: center; }
*+html #out { background-color:#F00; width:300px; height:300px; position:relative; overflow:hidden; }
*+html #mid { position:absolute; top:50%; left:50%; }
*+html #in { position:relative; top:-50%; left:-50%; }
</style>
</head>
<body>
<div class="container">
<div id="out">
<div id="mid">
<div id="in"> FF垂直居中FF直居中<br />
FF垂直居中F直居中<br />
FF垂直居中F直居中<br />
FF垂直居中F直居中<br />
</div>
</div>
</div>
</body>
</html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>IE6/7/8/FF垂直居中</title>
<style>
* { margin:0; padding:0; }
#out { display:table; background-color:#F00; width:300px; height:300px; _position:relative; overflow:hidden; }
#mid { vertical-align:middle; display:table-cell; _position:absolute; _top:50%; -left:50%; }
#in { _position:relative; _top:-50%; _left:-50%; text-align: center; }
*+html #out { background-color:#F00; width:300px; height:300px; position:relative; overflow:hidden; }
*+html #mid { position:absolute; top:50%; left:50%; }
*+html #in { position:relative; top:-50%; left:-50%; }
</style>
</head>
<body>
<div class="container">
<div id="out">
<div id="mid">
<div id="in"> FF垂直居中FF直居中<br />
FF垂直居中F直居中<br />
FF垂直居中F直居中<br />
FF垂直居中F直居中<br />
</div>
</div>
</div>
</body>
</html>
