19.相对定位

.box{
    width: 500px;
    height: 300px;
    border: solid;
    margin:50px auto;
}
.sub-box{
    width: 100px;
    height: 100px;
}
.bgc1{
    background-color: darkorange;
}
.bgc2{
    background-color: blue;
}
.bgc3{
    background-color: firebrick;
}
.po2{
    position: relative;
    left: 100px;
    top: -100px;
}
.po3{
    position: relative;
    left: 200px;
    top: -200px;
}

<div class="box">
    <div class="sub-box bgc1"></div>
    <div class="sub-box bgc2 po2"></div>
    <div class="sub-box bgc3 po3"></div>
</div>