css position:absolute 水平垂直居中对齐

此实例将div元素相对屏幕居中，css代码如下：.class{ position: absolute; left: 50%; width: 980px; margin-left: -490px; text-algin:center}...

.class{
 position: absolute;
 left: 50%;
 width: 980px;
 margin-left: -490px;
 text-algin:center
}