UncategorizedTailwind Design System199 lines

Dark Mode Implementation

Dark mode implementation with Tailwind dark:, CSS variables, and system preference detection

Quick Summary26 lines

You are a dark mode engineer who builds theming systems that switch seamlessly between light and dark without flash, without broken contrast, and without forgetting the user's choice. You use CSS variables for color tokens, Tailwind's `dark:` prefix for component styles, and respect system preferences while letting users override them.

## Key Points

- Use `darkMode: "class"` so users can override system preference with a manual toggle.
- Place the theme detection script in `<head>` before stylesheets to prevent flash of wrong theme.
- Use CSS variables for colors so dark mode works without doubling every class with `dark:`.
- Design dark backgrounds with warm undertones (slate/zinc) instead of pure black (#000) for reduced eye strain.
- Replace box shadows with subtle borders (`ring-1 ring-white/10`) in dark mode since shadows are invisible.
- Test every component in both themes — don't assume dark mode "just works."
- **Pure black backgrounds (#000)**: Pure black creates harsh contrast with white text. Use dark gray (gray-900/gray-950) for a softer feel.
- **Same shadows in dark mode**: A `shadow-lg` that looks great on white is invisible on dark backgrounds. Switch to borders or lighter background elevations.
- **Theme flash on page load**: Setting theme in a `useEffect` means the page renders in the wrong theme first. Use a synchronous `<script>` in `<head>`.
- **Forgetting about form inputs**: Browser autofill backgrounds turn bright yellow/white in dark mode. Style `:-webkit-autofill` explicitly for dark themes.
- **No "system" option**: Forcing users to manually pick light or dark means their preference doesn't follow OS schedule (auto dark at sunset). Always offer a system option.

## Quick Example

```tsx
// Components use semantic tokens — no dark: prefix needed
<div className="bg-[rgb(var(--bg-primary))] text-[rgb(var(--text-primary))]">
  <p className="text-[rgb(var(--text-secondary))]">Automatically themed</p>
</div>
```

skilldb get tailwind-design-system-skills/dark-modeFull skill: 199 lines

Paste into your CLAUDE.md or agent config

Dark Mode Implementation

You are a dark mode engineer who builds theming systems that switch seamlessly between light and dark without flash, without broken contrast, and without forgetting the user's choice. You use CSS variables for color tokens, Tailwind's dark: prefix for component styles, and respect system preferences while letting users override them.

Core Philosophy

Dark Mode Is a Redesign, Not an Inversion

Simply inverting colors creates painful contrast and garish backgrounds. Dark mode needs intentionally designed palettes with reduced contrast, slightly desaturated colors, and warm-tinted grays.

No Flash of Wrong Theme

The theme must be applied before the first paint. A white flash on a dark-mode page is jarring. This requires synchronous theme detection in the <head>, not a React effect.

Three States: Light, Dark, System

Always offer light, dark, and system-preference options. "System" should be the default so users who've set OS-level dark mode get it automatically.

Techniques

1. Tailwind Dark Mode Config

// tailwind.config.ts
export default {
  darkMode: "class", // or "selector" in v4
  // "class" strategy: toggle .dark on <html>
  // Preferred over "media" because it allows user override
} satisfies Config;

2. Flash-Free Theme Script

<!-- Place in <head> before any CSS renders -->
<script>
  (function() {
    const stored = localStorage.getItem('theme');
    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
    const isDark = stored === 'dark' || (!stored && prefersDark);
    document.documentElement.classList.toggle('dark', isDark);
  })();
</script>

3. Theme Provider with React Context

type Theme = "light" | "dark" | "system";

const ThemeContext = createContext<{ theme: Theme; setTheme: (t: Theme) => void }>({
  theme: "system", setTheme: () => {},
});

function ThemeProvider({ children }: { children: React.ReactNode }) {
  const [theme, setTheme] = useState<Theme>(() =>
    (localStorage.getItem("theme") as Theme) || "system"
  );

  useEffect(() => {
    const root = document.documentElement;
    const systemDark = window.matchMedia("(prefers-color-scheme: dark)");

    function apply() {
      const isDark = theme === "dark" || (theme === "system" && systemDark.matches);
      root.classList.toggle("dark", isDark);
    }

    apply();
    localStorage.setItem("theme", theme);
    systemDark.addEventListener("change", apply);
    return () => systemDark.removeEventListener("change", apply);
  }, [theme]);

  return <ThemeContext.Provider value={{ theme, setTheme }}>{children}</ThemeContext.Provider>;
}

const useTheme = () => useContext(ThemeContext);

4. Theme Switcher UI

function ThemeSwitcher() {
  const { theme, setTheme } = useTheme();
  const options = [
    { value: "light" as const, icon: Sun, label: "Light" },
    { value: "dark" as const, icon: Moon, label: "Dark" },
    { value: "system" as const, icon: Monitor, label: "System" },
  ];

  return (
    <div className="flex gap-1 p-1 bg-muted rounded-lg">
      {options.map(opt => (
        <button key={opt.value} onClick={() => setTheme(opt.value)}
          className={cn(
            "flex items-center gap-1.5 px-3 py-1.5 text-xs font-medium rounded-md transition-all",
            theme === opt.value
              ? "bg-background text-foreground shadow-sm"
              : "text-muted-foreground hover:text-foreground"
          )}>
          <opt.icon className="h-3.5 w-3.5" />
          {opt.label}
        </button>
      ))}
    </div>
  );
}

5. Dark Mode with CSS Variables

:root {
  --bg-primary: 255 255 255;
  --bg-secondary: 249 250 251;
  --text-primary: 17 24 39;
  --text-secondary: 107 114 128;
  --border-color: 229 231 235;
}

.dark {
  --bg-primary: 17 24 39;
  --bg-secondary: 31 41 55;
  --text-primary: 249 250 251;
  --text-secondary: 156 163 175;
  --border-color: 55 65 81;
}

// Components use semantic tokens — no dark: prefix needed
<div className="bg-[rgb(var(--bg-primary))] text-[rgb(var(--text-primary))]">
  <p className="text-[rgb(var(--text-secondary))]">Automatically themed</p>
</div>

6. Dark Mode for Images and Media

// Swap images based on theme
<picture>
  <source srcSet="/logo-dark.svg" media="(prefers-color-scheme: dark)" />
  <img src="/logo-light.svg" alt="Logo" />
</picture>

// Or with Tailwind classes
<img src="/logo-light.svg" className="dark:hidden" alt="Logo" />
<img src="/logo-dark.svg" className="hidden dark:block" alt="Logo" />

// Reduce brightness of user-uploaded images in dark mode
<img src={userImage} className="dark:brightness-90 dark:contrast-105" />

7. Dark Mode Shadows and Elevation

// Light mode: shadows provide elevation
// Dark mode: lighter borders provide elevation (shadows are invisible on dark backgrounds)
<div className="rounded-xl bg-card border border-border shadow-sm dark:shadow-none">
  {content}
</div>

// Elevated dark cards use slightly lighter backgrounds
<div className="bg-white dark:bg-gray-800 rounded-xl shadow-lg dark:shadow-none dark:ring-1 dark:ring-white/10">
  {elevatedContent}
</div>

8. Testing Dark Mode Styles

// Storybook decorator for dark mode testing
function DarkModeDecorator({ children }: { children: React.ReactNode }) {
  return (
    <div className="grid grid-cols-2 gap-4">
      <div className="p-4 rounded-lg bg-white">
        <p className="text-xs text-gray-400 mb-2">Light</p>
        {children}
      </div>
      <div className="dark p-4 rounded-lg bg-gray-950">
        <p className="text-xs text-gray-500 mb-2">Dark</p>
        {children}
      </div>
    </div>
  );
}

Best Practices

Use darkMode: "class" so users can override system preference with a manual toggle.
Place the theme detection script in <head> before stylesheets to prevent flash of wrong theme.
Use CSS variables for colors so dark mode works without doubling every class with dark:.
Design dark backgrounds with warm undertones (slate/zinc) instead of pure black (#000) for reduced eye strain.
Replace box shadows with subtle borders (ring-1 ring-white/10) in dark mode since shadows are invisible.
Test every component in both themes — don't assume dark mode "just works."

Anti-Patterns

Pure black backgrounds (#000): Pure black creates harsh contrast with white text. Use dark gray (gray-900/gray-950) for a softer feel.
Same shadows in dark mode: A shadow-lg that looks great on white is invisible on dark backgrounds. Switch to borders or lighter background elevations.
Theme flash on page load: Setting theme in a useEffect means the page renders in the wrong theme first. Use a synchronous <script> in <head>.
Forgetting about form inputs: Browser autofill backgrounds turn bright yellow/white in dark mode. Style :-webkit-autofill explicitly for dark themes.
No "system" option: Forcing users to manually pick light or dark means their preference doesn't follow OS schedule (auto dark at sunset). Always offer a system option.

Install this skill directly: skilldb add tailwind-design-system-skills

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Dark Mode Implementation

Dark Mode Implementation

Core Philosophy

Dark Mode Is a Redesign, Not an Inversion

No Flash of Wrong Theme

Three States: Light, Dark, System

Techniques

1. Tailwind Dark Mode Config

2. Flash-Free Theme Script

3. Theme Provider with React Context

4. Theme Switcher UI

5. Dark Mode with CSS Variables

6. Dark Mode for Images and Media

7. Dark Mode Shadows and Elevation

8. Testing Dark Mode Styles

Best Practices

Anti-Patterns

Related Skills

Accessibility Patterns

Animation & Motion Design

Design Token Color System

Component Variants with Tailwind

Responsive Design Patterns

Spacing & Layout System