JSFiddle - React, Tailwind, and code Playground

HTML

<div class="a">afsdf</div>

CSS

.a {
  background-color: red;
  height: 200px;
  width: 200px;
}
.rotated {
  opacity: .5;
  transform: rotateX(180deg)
}

JavaScript

var source = document.querySelector('.a')
var mirror = source.cloneNode(true)

mirror.classList.add('rotated')

document.body.appendChild(mirror)