li {
    list-style-type: none;
}
.sublist:nth-child(1) {
    background-color: red;
    width: 100px;
    height: 100px;
}
.sublist:nth-child(2) {
    z-index: 2;
    position: relative;
    bottom: 30px;
    left: 30px;
    background-color: blue;
    width: 100px;
    height: 100px;
}
.sublist:nth-child(3) {
    z-index: 1;
    background-color: green;
    width: 100px;
    height: 100px;
    position: relative;
    bottom: 50px;
    left: 70px;
}