<div class="row">
<div class="big diamond top"></div>
</div>
<div class="row">
<div class="small diamond"></div>
</div>
<div class="row">
<div class="big diamond bot"></div>
</div>
<style>
body {
background: #B8DCF0;
margin: 0;
}
.diamond {
background: #3F4869;
transform: rotate(45deg);
}
.big {
width: 8.7rem;
height: 8.7rem;
}
.top {translate: 0 -3rem}
.bot {translate: 0 3rem}
.small {
width: 4.45rem;
height: 4.45rem;
}
.row {
height: 33.3%;
display: grid;
place-content: center;
}
</style>