Dark Mode

The Tailwind v4 package supports dark mode through its semantic token system. Since all colors reference CSS variables, switching to dark mode is simply a matter of redefining those variables.

How It Works

The components use semantic utility classes like bg-primary, text-foreground, and border-border. These resolve to CSS variables (--color-primary, --color-foreground, etc.) that you define in your project’s CSS. Dark mode works by providing alternate values for these variables under a dark selector.

Setup

Using `data-theme` Attribute

Define light and dark token values using data-theme selectors:

@theme {
  --color-background: oklch(1 0 0);
  --color-foreground: oklch(0.145 0.004 285.823);
  --color-popover: oklch(1 0 0);
  --color-popover-foreground: oklch(0.145 0.004 285.823);
  --color-primary: oklch(0.205 0.006 285.885);
  --color-primary-foreground: oklch(0.985 0.001 285.823);
  --color-muted-foreground: oklch(0.556 0.01 285.823);
  --color-accent: oklch(0.96 0.003 285.823);
  --color-accent-foreground: oklch(0.205 0.006 285.885);
  --color-destructive: oklch(0.577 0.245 27.325);
  --color-border: oklch(0.922 0.004 285.823);
  --color-input: oklch(0.922 0.004 285.823);
  --color-ring: oklch(0.87 0.006 285.823);
}

[data-theme="dark"] {
  --color-background: oklch(0.145 0.004 285.823);
  --color-foreground: oklch(0.985 0.001 285.823);
  --color-popover: oklch(0.145 0.004 285.823);
  --color-popover-foreground: oklch(0.985 0.001 285.823);
  --color-primary: oklch(0.985 0.001 285.823);
  --color-primary-foreground: oklch(0.205 0.006 285.885);
  --color-muted-foreground: oklch(0.556 0.01 285.823);
  --color-accent: oklch(0.269 0.006 285.885);
  --color-accent-foreground: oklch(0.985 0.001 285.823);
  --color-destructive: oklch(0.577 0.245 27.325);
  --color-border: oklch(0.269 0.006 285.885);
  --color-input: oklch(0.269 0.006 285.885);
  --color-ring: oklch(0.369 0.006 285.885);
}

Toggle dark mode by setting the attribute:

function App() {
  const [dark, setDark] = useState(false);

  return (
    <div data-theme={dark ? "dark" : "light"}>
      <button onClick={() => setDark(!dark)}>Toggle Theme</button>
      <DatePicker value={value} onChange={setValue} />
    </div>
  );
}

Using `.dark` Class

If your framework uses a .dark class (e.g., Next.js with next-themes), define tokens under that class:

@theme {
  /* Light tokens */
  --color-background: oklch(1 0 0);
  --color-foreground: oklch(0.145 0.004 285.823);
  /* ... */
}

.dark {
  --color-background: oklch(0.145 0.004 285.823);
  --color-foreground: oklch(0.985 0.001 285.823);
  /* ... */
}

Using System Preference

Use @media (prefers-color-scheme: dark) to follow the OS setting:

@theme {
  /* Light tokens */
  --color-background: oklch(1 0 0);
  --color-foreground: oklch(0.145 0.004 285.823);
  /* ... */
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-background: oklch(0.145 0.004 285.823);
    --color-foreground: oklch(0.985 0.001 285.823);
    /* ... */
  }
}

Integration with next-themes

A common pattern with Next.js and next-themes:

import { ThemeProvider } from "next-themes";

export default function RootLayout({ children }) {
  return (
    <html suppressHydrationWarning>
      <body>
        <ThemeProvider attribute="class" defaultTheme="system">
          {children}
        </ThemeProvider>
      </body>
    </html>
  );
}

@theme {
  --color-background: oklch(1 0 0);
  --color-foreground: oklch(0.145 0.004 285.823);
  --color-primary: oklch(0.205 0.006 285.885);
  --color-primary-foreground: oklch(0.985 0.001 285.823);
  /* ... all light tokens */
}

.dark {
  --color-background: oklch(0.145 0.004 285.823);
  --color-foreground: oklch(0.985 0.001 285.823);
  --color-primary: oklch(0.985 0.001 285.823);
  --color-primary-foreground: oklch(0.205 0.006 285.885);
  /* ... all dark tokens */
}

The picker will automatically pick up the correct token values as the theme changes.

Highlight Dot in Dark Mode

The highlight dot uses after:bg-amber-500 dark:after:bg-amber-400 (a concrete Tailwind color, not a token) to ensure good visibility in both modes. This is the only non-semantic color in the component. If you need to change it, use the Compound Component API with a custom Day render:

<DatePicker.Day date={date}>
  {(props) => (
    <button /* ... */>
      {props.day}
      {props.isHighlighted && (
        <span className="absolute bottom-0.5 w-1 h-1 rounded-full bg-emerald-500 dark:bg-emerald-400" />
      )}
    </button>
  )}
</DatePicker.Day>

Forcing a Specific Mode

To force light or dark mode regardless of system preference, set the theme explicitly:

{
  /* Always light */
}
<div data-theme="light">
  <DatePicker value={value} onChange={setValue} />
</div>;

{
  /* Always dark */
}
<div data-theme="dark">
  <DatePicker value={value} onChange={setValue} />
</div>;