JSFiddle - React, Tailwind, and code Playground

HTML

<div class="ramka"></div>

CSS

body{
margin:0;
padding:0;
height:100%;
background:#ccc;
}

.ramka{
margin:100px auto;
width:300px;
height:300px;
background:#ccc;
outline:2px solid #fff;
border:2px solid #000;
position:relative;
}

.ramka:before{
content:'';
position:absolute;
left:1px;
right:1px;
top:1px;
bottom:1px;
border:2px solid #fff; 
}