.map-wrapper{
    position:relative;
}

.over {
    overflow-y: auto;
    background: white;
    position: absolute;
    z-index: 99;
    width: 22%;
    top: 0;
    height: 400px;
    opacity: 0.90;
    filter: alpha(opacity=90);
    color: #ffffff;
    /*extra stuff you need*/
    height: auto;
    top: 16px;
    bottom: 16px;
    left: 16px; /*or if you want to go to the edges switch from 16px to 0*/
}