JSFiddle - React, Tailwind, and code Playground

HTML

<div class="diagonal_line"></div>

CSS

.diagonal_line {
  border-bottom: 50px solid #212121;
  border-left: 8px solid rgba(255, 255, 255, 0);
  display: inline-block;
-webkit-transform: translate3d(0,0,0);
  -moz-transform: translate3d(0,0,0);
  -ms-transform: translate3d(0,0,0);
  -o-transform: translate3d(0,0,0);
  transform: translate3d(0,0,0);
}