JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div {
    height: 30px;
    width: 30px;
    background: #f00;
}

div:before {
    content: "";
    display: block;
    height: 30px;
    width: 30px;
    background: #0f0;
}

div:after {
    content: "";
    display: block;
    height: 30px;
    width: 30px;
    background: #00f;
}