<script src="https://cdn.tailwindcss.com"></script>
<style>
  /* button.css */
  .btn-primary {
    @apply bg-teal-500 text-white py-2 px-4 rounded hover:bg-blue-700;
  }
  /* It will work using npm, or simply on localhost, codepen unfortunately cannot interpret this in separate css. */
</style>
<main class="max-w-4xl mx-auto py-8 px-4">
  <!-- Content here -->
  <button class="btn-primary">Click here</button>
</main>