JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test"></div>

CSS

.test {
    width:150px;
    height:150px;
    background:yellow;
    border:1px solid #000;
    margin:3px;
    position:relative;
}
.test:before {
    position:absolute;

left:-3px;

bottom:-3px;
    outline:3px solid #000;
    content:"";
}