JAVASCRIPT

tailwind css dark mode

<div class="bg-white dark:bg-gray-800">
  <h1 class="text-gray-900 dark:text-white">Dark Mode!!</h1>
  <p class="text-gray-600 dark:text-gray-300">
    Example Text
  </p>
</div>

<script>
  // Change in Tailwinds Config.
  module.exports = {
  darkMode: 'media',
}
</script>

detect system dark mode tailwind css

// toggle  
const darkTheme = window.matchMedia("(prefers-color-scheme: dark)");
  if (darkTheme.matches) {
       document.documentElement.classList.add("dark");
    } else {
      document.documentElement.classList.remove("dark");
       }