<div class="box1">
<div class="box2"></div>
<div class="box3"></div>
</div>
<style>
body {
background: #F3AC3C;
display: flex;
justify-content: center;
align-items: center;
}
.box1 {
width: 200px;
height: 200px;
background: #1A4341;
position: relative;
}
.box2, .box3 {
position: absolute;
bottom: 0;
}
.box2 {
background: #998235;
width: 100px;
height: 100px;
left: 0;
}
.box3 {
background: #F3AC3C;
width: 50px;
height: 50px;
left: 50px;
}
</style>