JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    
    <div id="left">
        <p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p><p>Left contents</p>
    </div>
    
    <div id="right">
        <p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right contents</p><p>Right...

CSS

body, html {
  margin: 0;
  overflow: hidden;
}

#left {
  position: absolute;
  top: 0px;
  bottom: 0;
  left: 0;
  width: 75%;
  overflow-y: scroll;
  background-color: #FC6E51;
  text-align: center;
}

#right {
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  overflow-y: scroll;
  width: 25%;
  background-color: #4FC1E9;
  text-align: center;
}

*, *:before, *:after {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}