JSFiddle - React, Tailwind, and code Playground

HTML

<div id="title">Two boxes with the same width and height :</div>
<div id="shadow_inner_border"></div>
<div id="normal_border"></div>

CSS

#shadow_inner_border
{
    width:100px;
    height:100px;
    background-color:yellow;
    box-shadow:0px 0px 0px 10px black inset;
    margin-bottom:20px;
}

#normal_border
{
    border:10px solid black;
    width:100px;
    height:100px;
    background-color:red;
}

#title{
    color:green;
    margin-bottom:10px;
    
}