JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

.test-wrapper {
  align-items: center;
  background: aqua;
  display: flex;
  height: 100vh;
  justify-content: center;
  
}

.test-wrapper::after {
  border-left: 30px solid #000;
  border-top: 30px solid transparent;
  border-bottom: 30px solid transparent;
  content: '';
  display: flex;
}