<div class="container">
  <div class="item">1</div>
  <div class="item">2</div>
  <div class="item">3</div>
</div>
.container {
  border: 4px solid;
  display: flex;
  flex-direction: column;
}

.container .item {
  width: 100px;
  height: 100px;
  background-color: orange;
  font-size: 40px;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.