JSFiddle - React, Tailwind, and code Playground

HTML

<div id="doubleBorder">
  a double border
</div>

CSS

#doubleBorder {
   text-align:center;
   position:relative;
   z-index:10;
   padding:100px;
   background:#fff;
   border:6px solid red; 
}

#doubleBorder:before {
   content:"";
   display:block;
   position:absolute;
   z-index:-1;
   top:3px;
   left:3px;
   right:3px; 
   bottom:3px;
   border:6px solid blue;
}