设计系统

/* ===== Design Tokens ===== */
:root {
  /* 颜色系统 - 语义化命名 */
  --color-primary-50: #ecfeff;
  --color-primary-100: #cffafe;
  --color-primary-200: #a5f3fc;
  --color-primary-300: #67e8f9;
  --color-primary-400: #22d3ee;
  --color-primary-500: #06b6d4;
  --color-primary-600: #0891b2;
  --color-primary-700: #0e7490;
  --color-primary-800: #155e75;
  --color-primary-900: #164e63;

  /* 语义色 */
  --color-bg-primary: #0f172a;
  --color-bg-secondary: #1e293b;
  --color-bg-elevated: #334155;
  --color-text-primary: #f1f5f9;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-border-default: #334155;
  --color-border-focus: #06b6d4;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;
  --color-info: #06b6d4;

  /* 间距系统 - 4px基数 */
  --space-0: 0;
  --space-1: 0.25rem;  /* 4px */
  --space-2: 0.5rem;   /* 8px */
  --space-3: 0.75rem;  /* 12px */
  --space-4: 1rem;     /* 16px */
  --space-5: 1.25rem;  /* 20px */
  --space-6: 1.5rem;   /* 24px */
  --space-8: 2rem;     /* 32px */
  --space-10: 2.5rem;  /* 40px */
  --space-12: 3rem;    /* 48px */
  --space-16: 4rem;    /* 64px */

  /* 排版系统 */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'Fira Code', 'Consolas', monospace;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* 圆角 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* 阴影 */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.3);

  /* 过渡 */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
  --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

// 组件规范：Button
import { forwardRef } from 'react';
import styles from './Button.module.css';

export interface ButtonProps extends React.ButtonHTMLAttributes<HTMLButtonElement> {
  variant?: 'primary' | 'secondary' | 'ghost' | 'danger';
  size?: 'sm' | 'md' | 'lg';
  loading?: boolean;
  icon?: ReactNode;
  fullWidth?: boolean;
}

export const Button = forwardRef<HTMLButtonElement, ButtonProps>(
  ({ variant = 'primary', size = 'md', loading, icon, children, disabled, ...props }, ref) => {
    return (
      <button
        ref={ref}
        className={styles.button}
        data-variant={variant}
        data-size={size}
        data-loading={loading}
        disabled={disabled || loading}
        {...props}
      >
        {loading && <Spinner className={styles.spinner} />}
        {!loading && icon && <span className={styles.icon}>{icon}</span>}
        {children && <span className={styles.label}>{children}</span>}
      </button>
    );
  }
);

/* Button.module.css */
/*
.button {
  display: inline-flex; align-items: center; justify-content: center; gap: var(--space-2);
  font-family: var(--font-sans); font-weight: 500; border: none; cursor: pointer;
  transition: all var(--transition-fast); border-radius: var(--radius-md);
}
.button[data-size="sm"] { padding: var(--space-1) var(--space-3); font-size: var(--font-size-sm); }
.button[data-size="md"] { padding: var(--space-2) var(--space-4); font-size: var(--font-size-base); }
.button[data-size="lg"] { padding: var(--space-3) var(--space-6); font-size: var(--font-size-lg); }
.button[data-variant="primary"] { background: var(--color-primary-500); color: white; }
.button[data-variant="primary"]:hover { background: var(--color-primary-600); }
.button[data-variant="secondary"] { background: var(--color-bg-elevated); color: var(--color-text-primary); }
.button[data-variant="ghost"] { background: transparent; color: var(--color-text-secondary); }
.button[data-variant="danger"] { background: var(--color-error); color: white; }
.button:disabled { opacity: 0.5; cursor: not-allowed; }
*/

// 主题切换系统
import { createContext, useContext } from 'react';

type Theme = 'light' | 'dark' | 'system';
const ThemeContext = createContext<{ theme: Theme; setTheme: (t: Theme) => void }>({} as any);

function ThemeProvider({ children }: { children: ReactNode }) {
  const [theme, setTheme] = useLocalStorage<Theme>('theme', 'system');

  const resolvedTheme = theme === 'system'
    ? window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'
    : theme;

  useEffect(() => {
    document.documentElement.setAttribute('data-theme', resolvedTheme);
  }, [resolvedTheme]);

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