I think there are two ways to make a div center align through CSS.
.middleDiv {
position : absolute;
width : 200px;
height : 200px;
left : 50%;
top : 50%;
margin-left : -100px; /* half of the width */
margin-top : -100px; /* half of the height */
}
This is the simple and best way. for the demo please visit below link:
http://w3webpro.blogspot.in/2013/07/how-to-make-div-horizontally-and.html