JSFiddle - React, Tailwind, and code Playground

HTML

<div class="mydiv">hello</div>

CSS

.mydiv{
    position:absolute;
    top:0;
    left:0;
    width: 100%;
    background-color:#aaaaaa;
    padding:7px;
    -moz-box-sizing: padding-box;
    -webkit-box-sizing: padding-box; 
    box-sizing: padding-box;    
}