JSFiddle - React, Tailwind, and code Playground

HTML

<div id="watermark">
<p>WaterMark</p>
</div>

CSS

#watermark {
  color: #d0d0d0;
  font-size: 90pt;
  -webkit-transform: rotate(-45deg);
  -moz-transform: rotate(-45deg);
  transform: rotate(-45deg);
  position: fixed;
  width: 100%;
  height: 100%;
  margin: 0;
  z-index: 100;
  opacity: 0.5;
}