JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div {
  width: 30px;
  height: 200px;
  background: yellow;
  margin: 100px auto;
  position: relative;
}

div:before {
  content: '';
  position: absolute;
  border: 8px solid transparent;
  border-top: 8px solid yellow;
  border-right: 8px solid yellow;
  bottom: -16px;
  right: 0;
}

div:after {
  content: '';
  position: absolute;
  border: 8px solid transparent;
  border-top: 8px solid yellow;
  border-left: 8px solid yellow;
  bottom: -16px;
  left: 0;
}