Next.js with Tailwind Design System

# Next.js with Tailwind Design System

Build scalable design systems with Next.js and Tailwind CSS using Google Antigravity IDE. This comprehensive guide covers component architecture, theming, and accessibility patterns.

## Why Tailwind Design Systems?

Tailwind provides utility-first CSS with excellent customization. Google Antigravity IDE's Gemini 3 engine suggests component patterns and accessibility improvements.

## Theme Configuration

```typescript
// tailwind.config.ts
import type { Config } from "tailwindcss";

const config: Config = {
  content: ["./src/**/*.{js,ts,jsx,tsx,mdx}"],
  darkMode: "class",
  theme: {
    extend: {
      colors: {
        primary: {
          50: "#eff6ff",
          100: "#dbeafe",
          200: "#bfdbfe",
          300: "#93c5fd",
          400: "#60a5fa",
          500: "#3b82f6",
          600: "#2563eb",
          700: "#1d4ed8",
          800: "#1e40af",
          900: "#1e3a8a",
        },
        neutral: {
          50: "#fafafa",
          100: "#f5f5f5",
          200: "#e5e5e5",
          300: "#d4d4d4",
          400: "#a3a3a3",
          500: "#737373",
          600: "#525252",
          700: "#404040",
          800: "#262626",
          900: "#171717",
        },
      },
      fontFamily: {
        sans: ["Inter", "system-ui", "sans-serif"],
        mono: ["JetBrains Mono", "monospace"],
      },
      spacing: {
        "4.5": "1.125rem",
        "18": "4.5rem",
      },
      borderRadius: {
        "4xl": "2rem",
      },
      animation: {
        "fade-in": "fadeIn 0.2s ease-in-out",
        "slide-up": "slideUp 0.3s ease-out",
      },
      keyframes: {
        fadeIn: {
          "0%": { opacity: "0" },
          "100%": { opacity: "1" },
        },
        slideUp: {
          "0%": { transform: "translateY(10px)", opacity: "0" },
          "100%": { transform: "translateY(0)", opacity: "1" },
        },
      },
    },
  },
  plugins: [
    require("@tailwindcss/forms"),
    require("@tailwindcss/typography"),
  ],
};

export default config;
```

## Base Button Component

```typescript
// components/ui/Button.tsx
import { forwardRef, ButtonHTMLAttributes } from "react";
import { cva, type VariantProps } from "class-variance-authority";
import { cn } from "@/lib/utils";

const buttonVariants = cva(
  "inline-flex items-center justify-center rounded-lg font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50",
  {
    variants: {
      variant: {
        primary: "bg-primary-600 text-white hover:bg-primary-700 focus-visible:ring-primary-500",
        secondary: "bg-neutral-100 text-neutral-900 hover:bg-neutral-200 focus-visible:ring-neutral-500 dark:bg-neutral-800 dark:text-neutral-100",
        outline: "border border-neutral-300 bg-transparent hover:bg-neutral-100 focus-visible:ring-neutral-500 dark:border-neutral-700 dark:hover:bg-neutral-800",
        ghost: "hover:bg-neutral-100 dark:hover:bg-neutral-800",
        destructive: "bg-red-600 text-white hover:bg-red-700 focus-visible:ring-red-500",
        link: "text-primary-600 underline-offset-4 hover:underline",
      },
      size: {
        sm: "h-8 px-3 text-sm",
        md: "h-10 px-4 text-sm",
        lg: "h-12 px-6 text-base",
        icon: "h-10 w-10",
      },
    },
    defaultVariants: {
      variant: "primary",
      size: "md",
    },
  }
);

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

export const Button = forwardRef<HTMLButtonElement, ButtonProps>(
  ({ className, variant, size, loading, children, disabled, ...props }, ref) => {
    return (
      <button
        ref={ref}
        className={cn(buttonVariants({ variant, size }), className)}
        disabled={disabled || loading}
        {...props}
      >
        {loading && (
          <svg
            className="mr-2 h-4 w-4 animate-spin"
            xmlns="http://www.w3.org/2000/svg"
            fill="none"
            viewBox="0 0 24 24"
          >
            <circle
              className="opacity-25"
              cx="12"
              cy="12"
              r="10"
              stroke="currentColor"
              strokeWidth="4"
            />
            <path
              className="opacity-75"
              fill="currentColor"
              d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z"
            />
          </svg>
        )}
        {children}
      </button>
    );
  }
);

Button.displayName = "Button";
```

## Input Component

```typescript
// components/ui/Input.tsx
import { forwardRef, InputHTMLAttributes } from "react";
import { cn } from "@/lib/utils";

interface InputProps extends InputHTMLAttributes<HTMLInputElement> {
  label?: string;
  error?: string;
  hint?: string;
}

export const Input = forwardRef<HTMLInputElement, InputProps>(
  ({ className, label, error, hint, id, ...props }, ref) => {
    const inputId = id || props.name;
    
    return (
      <div className="w-full">
        {label && (
          <label
            htmlFor={inputId}
            className="mb-1.5 block text-sm font-medium text-neutral-700 dark:text-neutral-300"
          >
            {label}
          </label>
        )}
        <input
          ref={ref}
          id={inputId}
          className={cn(
            "flex h-10 w-full rounded-lg border bg-white px-3 py-2 text-sm",
            "placeholder:text-neutral-400",
            "focus:outline-none focus:ring-2 focus:ring-offset-2",
            error
              ? "border-red-500 focus:ring-red-500"
              : "border-neutral-300 focus:ring-primary-500 dark:border-neutral-700",
            "disabled:cursor-not-allowed disabled:opacity-50",
            "dark:bg-neutral-900 dark:text-white",
            className
          )}
          aria-invalid={error ? "true" : "false"}
          aria-describedby={error ? `${inputId}-error` : hint ? `${inputId}-hint` : undefined}
          {...props}
        />
        {error && (
          <p id={`${inputId}-error`} className="mt-1.5 text-sm text-red-600">
            {error}
          </p>
        )}
        {hint && !error && (
          <p id={`${inputId}-hint`} className="mt-1.5 text-sm text-neutral-500">
            {hint}
          </p>
        )}
      </div>
    );
  }
);

Input.displayName = "Input";
```

## Card Component

```typescript
// components/ui/Card.tsx
import { HTMLAttributes, forwardRef } from "react";
import { cn } from "@/lib/utils";

const Card = forwardRef<HTMLDivElement, HTMLAttributes<HTMLDivElement>>(
  ({ className, ...props }, ref) => (
    <div
      ref={ref}
      className={cn(
        "rounded-xl border border-neutral-200 bg-white shadow-sm",
        "dark:border-neutral-800 dark:bg-neutral-900",
        className
      )}
      {...props}
    />
  )
);

const CardHeader = forwardRef<HTMLDivElement, HTMLAttributes<HTMLDivElement>>(
  ({ className, ...props }, ref) => (
    <div ref={ref} className={cn("p-6 pb-0", className)} {...props} />
  )
);

const CardContent = forwardRef<HTMLDivElement, HTMLAttributes<HTMLDivElement>>(
  ({ className, ...props }, ref) => (
    <div ref={ref} className={cn("p-6", className)} {...props} />
  )
);

export { Card, CardHeader, CardContent };
```

## Best Practices

- Use CVA for variant management
- Apply proper dark mode support
- Implement accessible form controls
- Create consistent spacing tokens
- Use semantic color naming
- Add proper focus indicators

Google Antigravity IDE provides Tailwind component suggestions and automatically ensures accessibility compliance in your design system.