Centering div element onto the window.

gistfile1.css

div.classname {
    position:    absolute;
    left:        50%;        /* Start with top left in the center */
    top:         50%;
    width:       200px;      /* The div fixed width... */
    height:      100px;      /* ...and height */
    margin-left: -100px;     /* Shift over half the width */
    margin-top:  -50px;      /* Shift up half the height */
}

// Reference : http://stackoverflow.com/questions/2956671/how-to-keep-a-floating-div-centered-on-window-resize-jquery-css