JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

.container {
  background-color: #eee;
  padding: 1em;
}
.container:after {
  content: "";
  width: 0;
  height: 0;
  border-style: solid;
  border-width: 20.4px 10px 0 10px;
  border-color: yellow transparent transparent transparent;
  margin-left: .25em;
  display: inline-block;
  filter: drop-shadow(-6px -4px 0 green) drop-shadow(6px -4px 0 red) drop-shadow(0 6px 0 blue);
}