More than half of users prefer dark mode for reduced eye strain, especially in low-light environments. Users with photosensitivity rely on it. Implementing dark mode via prefers-color-scheme respects the user's OS preference without them needing to find a toggle, and CSS custom properties make it a clean, maintainable addition rather than a disruptive refactor.
Quick Reference
- Use @media (prefers-color-scheme: dark) to apply dark mode styles
- Define light/dark colors as CSS custom properties on :root for easy switching
- Support a manual toggle by storing preference in localStorage and setting a data-theme attribute
- Ensure dark mode colors maintain WCAG contrast ratios
Check
Check if this CSS supports dark mode. Look for prefers-color-scheme usage or a data-theme attribute pattern. Identify any hard-coded colors that would look wrong in dark mode.
Fix
Implement dark mode by extracting colors to CSS custom properties and redefining them inside a prefers-color-scheme: dark media query.
Explain
Explain how to implement dark mode with CSS custom properties, the prefers-color-scheme media query, and a JavaScript toggle for user preference.
Code Review
Review stylesheets, component styles, and responsive states related to Support dark mode with prefers-color-scheme. Flag exact selectors, declarations, or breakpoints that violate the rule in the rendered UI.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/css/dark-mode-css