JSFiddle - React, Tailwind, and code Playground

HTML

<div  class="one-edge-shadow"></div>

CSS

.one-edge-shadow {
    width:200px;
    height:200px;
     border-style: solid; 
    border-width: 1px;
	box-shadow: 10px 0 0 black, -10px 0 0 black;
}