Using Tailwind CSS to style your site in dark mode.
Now that dark mode is a first-class feature of many operating systems, it’s becoming more and more common to design a dark version of your website to go along with the default design.
To make this as easy as possible, Tailwind includes a dark variant that lets you style your site differently when dark mode is enabled:
<div class="bg-white dark:bg-gray-800">
<h1 class="text-gray-900 dark:text-white">Dark mode is here!</h1>
<p class="text-gray-600 dark:text-gray-300">
Lorem ipsum...
</p>
</div>It’s important to note that because of file size considerations, the dark mode variant is not enabled in Tailwind by default.
To enable it, set the darkMode option in your tailwind.config.js file to media:
// tailwind.config.js
module.exports = {
darkMode: 'media',
// ...
}Now whenever dark mode is enabled on the user’s operating system, dark:{class} classes will take precedence over unprefixed classes. The media strategy uses the prefers-color-scheme media feature under the hood, but if you’d like to support toggling dark mode manually, you can also use the ‘class’ strategy for more control.
By default, when darkMode is enabled dark variants are only generated for color-related classes, which includes text color, background color, border color, gradients, and placeholder color.
The dark variant can be combined with both responsive variants and state variants (like hover and focus):
<button class="lg:dark:hover:bg-white ...">
<!-- ... -->
</button>The responsive variant needs to come first, then dark, then the state variant for this to work.
To enable the dark variant for other utilities, add dark to the variants list for whatever utility you’d like to enable it for:
// tailwind.config.js
module.exports = {
// ...
variants: {
extend: {
textOpacity: ['dark']
}
}
}By default, the dark variant is enabled for backgroundColor, borderColor, gradientColorStops, placeholderColor, and textColor.
If you want to support toggling dark mode manually instead of relying on the operating system preference, use the class strategy instead of the media strategy:
// tailwind.config.js
module.exports = {
darkMode: 'class',
// ...
}Now instead of dark:{class} classes being applied based on prefers-color-scheme, they will be applied whenever dark class is present earlier in the HTML tree.
<!-- Dark mode not enabled -->
<html>
<body>
<!-- Will be white -->
<div class="bg-white dark:bg-black">
<!-- ... -->
</div>
</body>
</html>
<!-- Dark mode enabled -->
<html class="dark">
<body>
<!-- Will be black -->
<div class="bg-white dark:bg-black">
<!-- ... -->
</div>
</body>
</html>How you add the dark class to the html element is up to you, but a common approach is to use a bit of JS that reads a preference from somewhere (like localStorage) and updates the DOM accordingly.
Here’s a simple example of how you can support light mode, dark mode, as well as respecting the operating system preference:
// On page load or when changing themes, best to add inline in `head` to avoid FOUC
if (localStorage.theme === 'dark' || (!('theme' in localStorage) && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
document.documentElement.classList.add('dark')
} else {
document.documentElement.classList.remove('dark')
}
// Whenever the user explicitly chooses light mode
localStorage.theme = 'light'
// Whenever the user explicitly chooses dark mode
localStorage.theme = 'dark'
// Whenever the user explicitly chooses to respect the OS preference
localStorage.removeItem('theme')Again you can manage this however you like, even storing the preference server-side in a database and rendering the class on the server — it’s totally up to you.
When using the class strategy, the specificity of dark mode utilities will be higher than regular utilities because the selector contains an extra class. This means that in certain situations the behavior of some combination of utilities can be slightly different in class mode than it is in media mode.
For example, consider this HTML:
<div class="text-black text-opacity-50 dark:text-white">
<!-- ... -->
</div>When using the media strategy, dark:text-white has the same specificity as text-black and text-opacity-50. Because text-opacity-50 is defined later in the generated CSS than dark:text-white, the white text will have 50% opacity.
When using the class strategy, dark:text-white has a higher specificity, so even though it is defined sooner, it will actually override text-opacity-50 and reset the opacity back to 1. So when using the class strategy, you’ll need to re-specify the opacity in dark mode:
<div class="text-black text-opacity-50 dark:text-white dark:text-opacity-50">
<!-- ... -->
</div>