.floaters {
    position: relative;
    width: 900px;
    height: 720px;
    margin: auto;
}

.floaters div {
    position: absolute;
    background-repeat: no-repeat;
    z-index: -100;
}

.floaters div.base {
    position: absolute;
    background-repeat: no-repeat;
    z-index: -101;
}