JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

*{
  margin:0; 
  padding:0;
  box-sizing:border-box;
  -moz-box-sizing:border-box;
  -webkit-box-sizing:border-box;
}

div{
width: 100%;
height: 30px;
border:4px solid #000;
margin:20px;  
}