shadcn-customization

name	shadcn-customization
description	Shadcn/ui theming and component customization — CSS variables, OKLCH colors, dark mode, variants, wrappers. Load for any ticket involving colors, theme, UI layout, or component styling.

Customization & Theming

Components reference semantic CSS variable tokens. Change the variables to change every component.

---

How It Works

1. CSS variables defined in :root (light) and .dark (dark mode).
2. Tailwind maps them to utilities: bg-primary, text-muted-foreground, etc.
3. Components use these utilities — changing a variable changes all components that reference it.

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Color Variables

Every color follows the name / name-foreground convention. The base variable is for backgrounds, -foreground is for text/icons on that background.

Variable	Purpose
--background / --foreground	Page background and default text
--card / --card-foreground	Card surfaces
--primary / --primary-foreground	Primary buttons and actions
--secondary / --secondary-foreground	Secondary actions
--muted / --muted-foreground	Muted/disabled states
--accent / --accent-foreground	Hover and accent states
--destructive / --destructive-foreground	Error and destructive actions
--border	Default border color
--input	Form input borders
--ring	Focus ring color
--chart-1 through --chart-5	Chart/data visualization
--sidebar-*	Sidebar-specific colors
--surface / --surface-foreground	Secondary surface

Colors use OKLCH: --primary: oklch(0.205 0 0) where values are lightness (0–1), chroma (0 = gray), and hue (0–360).

---

Dark Mode

Class-based toggle via .dark on the root element. In Next.js, use next-themes:

import { ThemeProvider } from "next-themes"

<ThemeProvider attribute="class" defaultTheme="system" enableSystem>
  {children}
</ThemeProvider>

---

Changing the Theme

# Apply a preset from ui.shadcn.com.
npx shadcn@latest apply --preset a2r6bw

# Positional shorthand also works.
npx shadcn@latest apply a2r6bw

# Switch to a named preset, overwrite existing components.
npx shadcn@latest apply --preset nova

# Preserve existing components instead.
npx shadcn@latest init --preset nova --force --no-reinstall

# Use a custom theme URL.
npx shadcn@latest apply --preset "https://ui.shadcn.com/init?base=radix&style=nova&theme=blue&..."

Or edit CSS variables directly in globals.css.

---

Adding Custom Colors

Add variables to the file at tailwindCssFile from npx shadcn@latest info (typically globals.css). Never create a new CSS file for this.

/* 1. Define in the global CSS file. */
:root {
  --warning: oklch(0.84 0.16 84);
  --warning-foreground: oklch(0.28 0.07 46);
}
.dark {
  --warning: oklch(0.41 0.11 46);
  --warning-foreground: oklch(0.99 0.02 95);
}

/* 2a. Register with Tailwind v4 (@theme inline). */
@theme inline {
  --color-warning: var(--warning);
  --color-warning-foreground: var(--warning-foreground);
}

When tailwindVersion is "v3" (check via npx shadcn@latest info), register in tailwind.config.js instead:

// 2b. Register with Tailwind v3 (tailwind.config.js).
module.exports = {
  theme: {
    extend: {
      colors: {
        warning: "oklch(var(--warning) / <alpha-value>)",
        "warning-foreground": "oklch(var(--warning-foreground) / <alpha-value>)",
      },
    },
  },
}

// 3. Use in components.
<div className="bg-warning text-warning-foreground">Warning</div>

---

Border Radius

--radius controls border radius globally. Components derive values from it (rounded-lg = var(--radius), rounded-md = calc(var(--radius) - 2px)).

---

Customizing Components

Prefer these approaches in order:

1. Built-in variants

<Button variant="outline" size="sm">Click</Button>

2. Tailwind classes via className

<Card className="mx-auto max-w-md">...</Card>

3. Add a new variant

Edit the component source to add a variant via cva:

// components/ui/button.tsx
warning: "bg-warning text-warning-foreground hover:bg-warning/90",

4. Wrapper components

Compose shadcn/ui primitives into higher-level components:

export function ConfirmDialog({ title, description, onConfirm, children }) {
  return (
    <AlertDialog>
      <AlertDialogTrigger asChild>{children}</AlertDialogTrigger>
      <AlertDialogContent>
        <AlertDialogHeader>
          <AlertDialogTitle>{title}</AlertDialogTitle>
          <AlertDialogDescription>{description}</AlertDialogDescription>
        </AlertDialogHeader>
        <AlertDialogFooter>
          <AlertDialogCancel>Cancel</AlertDialogCancel>
          <AlertDialogAction onClick={onConfirm}>Confirm</AlertDialogAction>
        </AlertDialogFooter>
      </AlertDialogContent>
    </AlertDialog>
  )
}

---

Checking for Updates

npx shadcn@latest add button --diff
npx shadcn@latest add button --dry-run        # see all affected files
npx shadcn@latest add button --diff button.tsx # diff for a specific file