Support dark mode with prefers-color-scheme

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.