CSS 上下置中

<style>
html,body{
margin:0;
height:100%;
width:100%;
}
#in_wrap{
margin:0 auto;
text-align:center;
}
</style>


<div id="in_wrap" class="greenBorder" style="display: table; width:800px;height: 100%; #position: relative; overflow: hidden;">
<div style=" #position: absolute; #top: 50%;display: table-cell; vertical-align: middle;">
<div class="greenBorder" style="#position: relative; #top: -50%; ">
這裡寫要使用的吧
</div>
</div>
</div>