loading上下左右居中

.loading {
50px;
height: 60px;
text-align: center;
font-size: 10px;
position:fixed;
left:50%;
top:50%;
margin-top:-30px;
margin-left:-25px;
}

http://www.cnblogs.com/lhb25/p/loading-spinners-animated-with-css3.html

loading各种效果