JSFiddle - React, Tailwind, and code Playground

by CntChen

HTML

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

CSS

.a {
  border: 1px solid green;
  width: 100%;
  height: 100%;
  position: absolute;
  z-index: 100;
}

.b {
  border: 1px solid red;
  width: 100%;
  height: 2000px;
}