JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<body>
    
<div id="over">
Hello Hello HelloHelloHelloHelloHello Hello Hello Hello Hello Hello Hello Hello Hello Hello Hello
</div>  

<div id="under">
 
</div>
</body>
</html>





</body>
</html>

CSS

#over {
  width: 600px;
  z-index: 10;
  position: relative;    
}

#under {
  position: fixed;
  top: 5px;
  width: 420px;
  left: 20px;
  border: 1px solid;
  height: 10%;
  background: #fff;
  z-index: 1;
}