.divOuter {
    display: table;
    position: absolute;
    height: 100%;
    width: 100%;
}

.divMiddle {
    display: table-cell;
    vertical-align: middle;
}

.divInner {
    margin-left: auto;
    margin-right: auto; 
    height: 482px;
    width: 723px;
    border: 1px solid black;
}