JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <span></span>
</div>

CSS

div{
    position: relative;
    width: 300px;
    height: 300px;
    background: #00f;
}
span{
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border: 10px solid rgba(255, 255, 255, 0.5);
}