Applying Dark Mode Styles in CSS

Dark Mode in CSS is a feature that allows websites and web applications to adjust their appearance to a darker color scheme, making it easier on the eyes, especially in low-light environments. It's become increasingly popular due to its aesthetic appeal and its potential benefits for user experience. It offers several benefits, including:

  1. Reduced eye strain: Dark backgrounds are easier on the eyes in low-light environments.
  2. Improved battery life: On mobile devices, displaying fewer bright pixels can conserve battery life.
  3. Modern aesthetic: Dark mode can create a sleek and modern look for your website.

Dark Mode can be implemented using CSS media queries, CSS variables, or JavaScript, and it typically involves changing the colors of various elements on the webpage.

CSS Media Queries

Media queries are a powerful feature in CSS that allow you to apply different styles based on the characteristics of the device or viewport. With media queries, you can detect if the user's device has a preference for a dark color scheme and adjust the styles accordingly.

/* Define styles for light mode */ body { background-color: #ffffff; color: #333333; } /* Media query for dark mode */ @media (prefers-color-scheme: dark) { body { background-color: #333333; color: #ffffff; } }

In this example, the background color and text color of the webpage are adjusted based on the user's preference for a dark color scheme. The prefers-color-scheme media query checks if the user's device has a preference for dark mode.

CSS Variables

CSS variables, also known as custom properties, allow you to define reusable values in CSS. By using CSS variables, you can easily switch between light and dark modes by changing the values of these variables.

:root { --background-color: #ffffff; --text-color: #333333; } body { background-color: var(--background-color); color: var(--text-color); } /* Dark mode */ @media (prefers-color-scheme: dark) { :root { --background-color: #333333; --text-color: #ffffff; } }

Here, CSS variables --background-color and --text-color are defined at the :root level and used throughout the stylesheet. Dark mode is implemented by changing the values of these variables within a media query.

Using light-dark() color function

This function returns the first color for light mode and the second for dark mode:

body { background-color: light-dark(#fff, #222); color: light-dark(#333, #fff); }


While CSS alone can handle most cases of Dark Mode implementation, JavaScript can be used to provide additional flexibility and control, especially in more complex scenarios or for browsers that don't support certain CSS features.

// Check if the user prefers dark mode if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) { document.documentElement.classList.add('dark-mode'); } // CSS rules for dark mode .dark-mode { background-color: #333333; color: #ffffff; }

This JavaScript code checks if the user prefers dark mode using window.matchMedia and adds a class dark-mode to the html element if the condition is met. Then, CSS rules for dark mode are defined to style the webpage accordingly.

Using a framework

Many CSS frameworks like Bootstrap and Materialize offer built-in dark mode support.

Additional Notes:

When implementing dark mode in CSS, it's crucial to do more than simply swapping black and white colors. To ensure good readability, it's essential to use contrasting colors that maintain clarity. Adjusting text weight or line-height can also enhance the reading experience in dark mode, ensuring that text remains legible against darker backgrounds. Additionally, considering accessibility when selecting colors and contrasts is vital to ensure that all users, including those with visual impairments, can comfortably navigate the content. Thoroughly testing your dark mode implementation across various devices and screen sizes is necessary to confirm its effectiveness and usability in different contexts.


Dark Mode in CSS involves adjusting the color scheme of a webpage to a darker palette, typically with dark backgrounds and light text. It's important to consider readability by using contrasting colors, adjusting text weight or line-height, and ensuring accessibility for all users. Thorough testing is essential to verify the effectiveness and usability of the dark mode implementation across various devices and screen sizes.