JSFiddle - React, Tailwind, and code Playground

HTML

<div class="foo"></div>

CSS

.foo {
  width: 50px;
  height: 90px;
  background: red;
  display: flex;
  align-items: center;
}

.foo::before {
  content: '';
  display: block;
  height: 20px;
  width: 30px;
  flex: 5;
  background: black;
}