JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="top"></div>
  <div class="bottom"></div>
</div>

CSS

.container {
  padding: 20px;
  height: 100%;
}

.top {
  height: 100px;
  width: 50px;
  border-left: 1px solid darkgrey;
  border-bottom: 1px solid darkgrey;
  transform: skew(0, 45deg);
}

.bottom {
  margin-top: 50px;
  height: 100px;
  width: 50px;
  border-left: 1px solid darkgrey;
  border-top: 1px solid darkgrey;
  transform: skew(0, -45deg);
}