JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="box">This div occupies the left half.</div>
  <div class="box">This div occupies the right half.</div>
</div>

CSS

.container{
width:30em;
border:1em solid;
overflow: hidden;
}
.box{
box-sizing: border-box;
-moz-box-sizing: border-box; /* Firefox */
-webkit-box-sizing: border-box; /* Safari */
width:50%;
border:20px solid red;
float:left;
}