JSFiddle - React, Tailwind, and code Playground

HTML

<div id="d1"></div>
<div id="d2"></div>

CSS

body {
  margin: 0;
  display: inline-block;
}

#d1 {
  background: red;
  position: sticky;
  top: 0;
  width: 2000px;
  height: 50px;
  opacity: 0.8;
}

#d2 {
  background: blue;
  position: sticky;
  left: 0;
  width: 50px;
  height: 2000px;
  opacity: 0.8;
}