<div class="box">
  <div class="blue"></div>
  <div class="green"></div>
    <div class="blue"></div>
  <div class="green"></div>
 <div class="blue"></div>
    <div class="green"></div>
  <div class="blue"></div>
</div>
      
.box {
  display: flex;
  align-items: center;

  justify-content: center;
  height: 200px;
  
  flex-wrap: wrap;
  flex-direction: column;

}

.box div {
  width: 100px;
  height: 100px;
  margin:5px;

}

.blue {
    background-color:blue;
}

.green {
    background-color:green;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.