JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<head>
<style>

</style>
</head>
<body>
  <main>
      <h1>My 2nd CSS Example</h1>
      <div class="fixed">
      	This is a paragraph.
        <br>This is a paragraph.
      </div>
      <div class="scrolled">
      	This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This is a paragraph.
        <br>This...

CSS

body {
  background-color: lightblue;
  padding: 15px;
}

main {
  background-color: #999;
}

h1 {
  text-align: center;
}

.fixed {
  background: #c0c;
}
.scrolled {
  background: #cc0;
  overflow-y: auto;
  height: 100%;
  max-height: 100%;
}