design-system-patterns

name	design-system-patterns
description	Build scalable design systems with design tokens, theming infrastructure, and component architecture patterns. Use when creating design tokens, implementing theme switching, building component libraries, or establishing design system foundations.

Design System Patterns

Master design system architecture to create consistent, maintainable, and scalable UI foundations across web and mobile applications.

When to Use This Skill

• Creating design tokens for colors, typography, spacing, and shadows
• Implementing light/dark theme switching with CSS custom properties
• Building multi-brand theming systems
• Architecting component libraries with consistent APIs
• Establishing design-to-code workflows with Figma tokens
• Creating semantic token hierarchies (primitive, semantic, component)
• Setting up design system documentation and guidelines

Core Capabilities

1. Design Tokens

• Primitive tokens (raw values: colors, sizes, fonts)
• Semantic tokens (contextual meaning: text-primary, surface-elevated)
• Component tokens (specific usage: button-bg, card-border)
• Token naming conventions and organization
• Multi-platform token generation (CSS, iOS, Android)

2. Theming Infrastructure

• CSS custom properties architecture
• Theme context providers in React
• Dynamic theme switching
• System preference detection (prefers-color-scheme)
• Persistent theme storage
• Reduced motion and high contrast modes

3. Component Architecture

• Compound component patterns
• Polymorphic components (as prop)
• Variant and size systems
• Slot-based composition
• Headless UI patterns
• Style props and responsive variants

4. Token Pipeline

• Figma to code synchronization
• Style Dictionary configuration
• Token transformation and formatting
• CI/CD integration for token updates

Quick Start

// Design tokens with CSS custom properties
const tokens = {
  colors: {
    // Primitive tokens
    gray: {
      50: "#fafafa",
      100: "#f5f5f5",
      900: "#171717",
    },
    blue: {
      500: "#3b82f6",
      600: "#2563eb",
    },
  },
  // Semantic tokens (reference primitives)
  semantic: {
    light: {
      "text-primary": "var(--color-gray-900)",
      "text-secondary": "var(--color-gray-600)",
      "surface-default": "var(--color-white)",
      "surface-elevated": "var(--color-gray-50)",
      "border-default": "var(--color-gray-200)",
      "interactive-primary": "var(--color-blue-500)",
    },
    dark: {
      "text-primary": "var(--color-gray-50)",
      "text-secondary": "var(--color-gray-400)",
      "surface-default": "var(--color-gray-900)",
      "surface-elevated": "var(--color-gray-800)",
      "border-default": "var(--color-gray-700)",
      "interactive-primary": "var(--color-blue-400)",
    },
  },
};

Key Patterns

Pattern 1: Token Hierarchy

/* Layer 1: Primitive tokens (raw values) */
:root {
  --color-blue-500: #3b82f6;
  --color-blue-600: #2563eb;
  --color-gray-50: #fafafa;
  --color-gray-900: #171717;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-4: 1rem;

  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;

  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
}

/* Layer 2: Semantic tokens (meaning) */
:root {
  --text-primary: var(--color-gray-900);
  --text-secondary: var(--color-gray-600);
  --surface-default: white;
  --interactive-primary: var(--color-blue-500);
  --interactive-primary-hover: var(--color-blue-600);
}

/* Layer 3: Component tokens (specific usage) */
:root {
  --button-bg: var(--interactive-primary);
  --button-bg-hover: var(--interactive-primary-hover);
  --button-text: white;
  --button-radius: var(--radius-md);
  --button-padding-x: var(--space-4);
  --button-padding-y: var(--space-2);
}

Pattern 2: Theme Switching with React

import { createContext, useContext, useEffect, useState } from "react";

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

interface ThemeContextValue {
  theme: Theme;
  resolvedTheme: "light" | "dark";
  setTheme: (theme: Theme) => void;
}

const ThemeContext = createContext<ThemeContextValue | null>(null);

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

  const [resolvedTheme, setResolvedTheme] = useState<"light" | "dark">("light");

  useEffect(() => {
    const root = document.documentElement;

    const applyTheme = (isDark: boolean) => {
      root.classList.remove("light", "dark");
      root.classList.add(isDark ? "dark" : "light");
      setResolvedTheme(isDark ? "dark" : "light");
    };

    if (theme === "system") {
      const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)");
      applyTheme(mediaQuery.matches);

      const handler = (e: MediaQueryListEvent) => applyTheme(e.matches);
      mediaQuery.addEventListener("change", handler);
      return () => mediaQuery.removeEventListener("change", handler);
    } else {
      applyTheme(theme === "dark");
    }
  }, [theme]);

  useEffect(() => {
    localStorage.setItem("theme", theme);
  }, [theme]);

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

export const useTheme = () => {
  const context = useContext(ThemeContext);
  if (!context) throw new Error("useTheme must be used within ThemeProvider");
  return context;
};

Pattern 3: Variant System with CVA

import { cva, type VariantProps } from "class-variance-authority";
import { cn } from "@/lib/utils";

const buttonVariants = cva(
  // Base styles
  "inline-flex items-center justify-center rounded-md font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 disabled:pointer-events-none disabled:opacity-50",
  {
    variants: {
      variant: {
        default: "bg-primary text-primary-foreground hover:bg-primary/90",
        destructive:
          "bg-destructive text-destructive-foreground hover:bg-destructive/90",
        outline:
          "border border-input bg-background hover:bg-accent hover:text-accent-foreground",
        secondary:
          "bg-secondary text-secondary-foreground hover:bg-secondary/80",
        ghost: "hover:bg-accent hover:text-accent-foreground",
        link: "text-primary underline-offset-4 hover:underline",
      },
      size: {
        sm: "h-9 px-3 text-sm",
        md: "h-10 px-4 text-sm",
        lg: "h-11 px-8 text-base",
        icon: "h-10 w-10",
      },
    },
    defaultVariants: {
      variant: "default",
      size: "md",
    },
  },
);

interface ButtonProps
  extends
    React.ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof buttonVariants> {
  asChild?: boolean;
}

export function Button({ className, variant, size, ...props }: ButtonProps) {
  return (
    <button
      className={cn(buttonVariants({ variant, size, className }))}
      {...props}
    />
  );
}

Pattern 4: Style Dictionary Configuration

// style-dictionary.config.js
module.exports = {
  source: ["tokens/**/*.json"],
  platforms: {
    css: {
      transformGroup: "css",
      buildPath: "dist/css/",
      files: [
        {
          destination: "variables.css",
          format: "css/variables",
          options: {
            outputReferences: true, // Preserve token references
          },
        },
      ],
    },
    scss: {
      transformGroup: "scss",
      buildPath: "dist/scss/",
      files: [
        {
          destination: "_variables.scss",
          format: "scss/variables",
        },
      ],
    },
    ios: {
      transformGroup: "ios-swift",
      buildPath: "dist/ios/",
      files: [
        {
          destination: "DesignTokens.swift",
          format: "ios-swift/class.swift",
          className: "DesignTokens",
        },
      ],
    },
    android: {
      transformGroup: "android",
      buildPath: "dist/android/",
      files: [
        {
          destination: "colors.xml",
          format: "android/colors",
          filter: { attributes: { category: "color" } },
        },
      ],
    },
  },
};

Best Practices

1. Name Tokens by Purpose: Use semantic names (text-primary) not visual descriptions (dark-gray)
2. Maintain Token Hierarchy: Primitives > Semantic > Component tokens
3. Document Token Usage: Include usage guidelines with token definitions
4. Version Tokens: Treat token changes as API changes with semver
5. Test Theme Combinations: Verify all themes work with all components
6. Automate Token Pipeline: CI/CD for Figma-to-code synchronization
7. Provide Migration Paths: Deprecate tokens gradually with clear alternatives

Common Issues

• Token Sprawl: Too many tokens without clear hierarchy
• Inconsistent Naming: Mixed conventions (camelCase vs kebab-case)
• Missing Dark Mode: Tokens that don't adapt to theme changes
• Hardcoded Values: Using raw values instead of tokens
• Circular References: Tokens referencing each other in loops
• Platform Gaps: Tokens missing for some platforms (web but not mobile)