JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="pairsWithinContainer">
        <div>
        </div>
        <div>
        </div>
    </div>
    <div class="pairsWithinContainer">
        <div>
        </div>
        <div>
        </div>
    </div>
</div>

CSS

.container {
  width: 100%;
  height: 200px;
  background-color: blue;
  padding: 2px;
}

.container > div {
  display: inline-block;
  width: 49.5%;
  height: 200px;
  background-color: yellow; 
}

.pairsWithinContainer > div {
  display: inline-block;
  background-color: green;
  width: 50px;
  height: 100%;
}