JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
  <div class="child">
    chto-to
  </div>
</div>

CSS

div {
    width: 50px;
    height: 50px;
}
.parent {
  z-index: 1;
  background: #f00;
}
.child {
  z-index: 2;
  position: fixed;
  background: #333;
  top: 30px;
  left: 3px;
}