CSS custom properties enable powerful theming systems. Here's how to build flexible, maintainable themes.
Basic Custom Properties#
Dark Mode#
Color Scales#
Component Theming#
Dynamic Values with JavaScript#
Animation Variables#
Responsive Variables#
Scoped Themes#
Best Practices#
Organization:
✓ Use semantic variable names
✓ Create color scales
✓ Group related variables
✓ Document variable purpose
Theming:
✓ Support system preference
✓ Persist user choice
✓ Avoid flash of wrong theme
✓ Test both themes thoroughly
Performance:
✓ Define variables at :root
✓ Avoid excessive recalculation
✓ Use fallback values
✓ Minimize JavaScript updates
Conclusion#
CSS custom properties create flexible, maintainable theming systems. Define semantic variables, support dark mode with system preference detection, and use component-level variables for reusable patterns. The result is a theming system that's easy to extend and maintain.