JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div {
    position: relative;
    width: 100px;
    height: 50px;
    border-top: 2px solid black;
    border-left: 2px solid black;
}

div:before {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 50%;
    height: 2px;
    background: black;
}

div:after {
    content: '';
    position: absolute;
    right: 0;
    top: 0;
    height: 50%;
    width: 2px;
    background: black;
}