JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box_parent">
      <div class="box" style="background:red">50vw</div>
      <div class="box" style="background:green">50vw</div>
    </div>

CSS

*{
  box-sizing:border-box;
  margin:0;
}
.box_parent{
  width:100vw;
}
.box{
  display:block; 
  background:black; 
  height:100vh; 
  width:50%;
  float:left;
}