JSFiddle - React, Tailwind, and code Playground

HTML

<div class="contact-form"></div>

CSS

.contact-form {
  height: 320px;
  max-width: 500px;
  margin: 0 auto;
  position: relative;
}

.contact-form::after {
    position:absolute;
    content:"";
    left: 0;
    top:0;
    width: 90%;
    height: 98%;
    float: left;
    border-bottom: 4px solid #000;
}

.contact-form::before {
    position:absolute;
    content:"";
    right: 0;
    top:-2px;
    width: 90%;
    height: 80%;
    float: left;
    border-right: 4px solid #000;
    border-top: 4px solid #000;
}