JSFiddle - React, Tailwind, and code Playground

HTML

<div id="box">Text will be here</div>

CSS

body, html {
     width: 100%;
     height: 100%;
     margin: 0;
 }

body
{
    padding: 20px;
    box-sizing: border-box;
}

 #box {
     width: 100%;
     height: 100%;
     border: 5px solid red;
     padding: 15px;
     /*margin: 20px;*/
     box-sizing: border-box;
 }