Shadcn Patterns

shadcn/ui Patterns

Beautifully designed, accessible components you own and customize.

Core Pattern: CVA (Class Variance Authority)

Declarative, type-safe variant definitions:

import { cva, type VariantProps } from 'class-variance-authority'

const buttonVariants = cva(
  // Base classes (always applied)
  'inline-flex items-center justify-center rounded-md font-medium transition-colors',
  {
    variants: {
      variant: {
        default: 'bg-primary text-primary-foreground hover:bg-primary/90',
        destructive: 'bg-destructive text-destructive-foreground',
        outline: 'border border-input bg-background hover:bg-accent',
        ghost: 'hover:bg-accent hover:text-accent-foreground',
      },
      size: {
        default: 'h-10 px-4 py-2',
        sm: 'h-9 px-3',
        lg: 'h-11 px-8',
        icon: 'h-10 w-10',
      },
    },
    compoundVariants: [
      { variant: 'outline', size: 'lg', className: 'border-2' },
    ],
    defaultVariants: {
      variant: 'default',
      size: 'default',
    },
  }
)

// Type-safe props
interface ButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof buttonVariants> {}

Core Pattern: cn() Utility

Combines clsx + tailwind-merge for conflict resolution:

import { clsx, type ClassValue } from 'clsx'
import { twMerge } from 'tailwind-merge'

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs))
}

// Usage - later classes win
cn('px-4 py-2', 'px-6') // => 'py-2 px-6'
cn('text-red-500', condition && 'text-blue-500')

OKLCH Theming (2026 Standard)

Modern perceptually uniform color space:

:root {
  --background: oklch(1 0 0);
  --foreground: oklch(0.145 0 0);
  --primary: oklch(0.205 0 0);
  --primary-foreground: oklch(0.985 0 0);
  --destructive: oklch(0.577 0.245 27.325);
  --border: oklch(0.922 0 0);
  --ring: oklch(0.708 0 0);
  --radius: 0.625rem;
}

.dark {
  --background: oklch(0.145 0 0);
  --foreground: oklch(0.985 0 0);
  --primary: oklch(0.985 0 0);
  --destructive: oklch(0.396 0.141 25.723);
}

Why OKLCH?

• Perceptually uniform (equal steps look equal)
• Better dark mode contrast
• Wide gamut support
• Format: oklch(lightness chroma hue)

Component Extension Strategy

Wrap, don't modify source:

import { Button as ShadcnButton } from '@/components/ui/button'

// Extend with new variants
const Button = React.forwardRef<
  React.ElementRef<typeof ShadcnButton>,
  React.ComponentPropsWithoutRef<typeof ShadcnButton> & {
    loading?: boolean
  }
>(({ loading, children, disabled, ...props }, ref) => (
  <ShadcnButton ref={ref} disabled={disabled || loading} {...props}>
    {loading && <Spinner className="mr-2" />}
    {children}
  </ShadcnButton>
))

Quick Reference

# Add components
npx shadcn@latest add button
npx shadcn@latest add dialog

# Initialize in project
npx shadcn@latest init

Key Decisions

Related Skills

• radix-primitives - Underlying accessibility primitives
• design-system-starter - Design system patterns
• biome-linting - Code quality for components

References

• CVA Variant System - CVA patterns
• OKLCH Theming - Modern color space
• cn() Utility - Class merging
• Component Extension - Extending components
• Dark Mode - next-themes integration