Dark Mode — Implementing Themes the Right Way
Implement a complete dark mode system with CSS variables, next-themes, and system preference detection.
13 min readdark-mode, theming, css, next-themes, web-dev
Dark mode isn't a trend — it's an expectation. Users want it, operating systems support it, and every major application offers it. But implementing dark mode poorly leads to flash-of-wrong-theme on page load, colors that don't work in both modes, and maintenance headaches where every new component needs two sets of colors.
This lesson covers the approach that actually works: CSS custom properties for theming, next-themes for state management, and Tailwind's dark mode utilities for styling.
The Architecture
A proper dark mode implementation has three layers:
- Theme state — tracks which theme is active (light, dark, or system)
- CSS variables — define the color values for each theme
- Component styles — reference variables instead of hardcoded colors
When the theme
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