JSFiddle - React, Tailwind, and code Playground

HTML

<div>hello
</div>

CSS

div:before{
    position: absolute;
    width:3px;height:3px;
    background:red;
    content:'';
}
div {
    position: relative;
    border:1px solid green;
    height:200px;
    background-color:yellow;
}