<div class="container">
  <div class="box-1">1</div>
  <div class="box-2">2</div>
  <div class="box-3">3</div>
  <div class="box-4">4</div>
</div>
/* PARENT ELEMENT */
.container {
  border: 5px solid orange;
  background-color: black;
  display: flex;
  /*     justify-content: space-between; */
}

/* CHILDREN ELEMENTS */
.box-1,
.box-2,
.box-3,
.box-4 {
  width: 10%;
  height: 80vh;
  text-align: center;
  font-weight: bold;
  font-size: 1.5rem;
  color: lightgray;
}

.box-1 {
  background-color: red;
}

.box-2 {
  background-color: blue;
}

.box-3 {
  background-color: purple;
}

.box-4 {
  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.