JSFiddle - React, Tailwind, and code Playground

HTML

<div class="red">
  <div class="blue-transparent">
    
  </div>
</div>

CSS

.red {
  width: 100px;
  height: 100px;
  background-color: rgba(204, 51, 0, 1)
}

.blue-transparent {
    width: 100px;
  height: 100px;
  background-color: rgba(77, 148, 255, 0.4)
}