JSFiddle - React, Tailwind, and code Playground

HTML

<div class="b">
    <div class="a" ></div>
    <div class="a" ></div>
    <div class="a" ></div>
</div>

CSS

.b {
  height: 300px;   
}

.a {
  width: 100px;
  margin: 5px;
  background-color: black;
  height: 33.33%;
}