/* CSS Document */
#mydiv {
position:absolute;
top: 60%;
left: 50%;
width:31em;
height:auto;
margin-top: -9em; /*set to a negative number 1/2 of your height*/
margin-left: -15em; /*set to a negative number 1/2 of your width*/
border: 1px solid #ccc;
background-color: #02599E;
z-index:10;}