<div class="box"></div>
<div class="box"></div>
<div class="box"></div>
body{
  margin: 0;
}

.box{
  width: 150px;
  height: 150px;
}

.box:nth-child(1){
  background: green;
}

.box:nth-child(2){
  background: red;
  width: 100px;
  height: 100px;
}

.box:nth-child(3){
  background: blue;
  width: 50px;
  height: 50px;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.