/* ========================================
   CSS Variables / Design Tokens
   ======================================== */

:root {
  /* Colors */
  --color-primary: #1a2a3a;
  --color-secondary: #3a5a7c;
  --color-accent: #4a9eff;
  --color-accent-hover: #6bb3ff;
  --color-background: #0d1117;
  --color-surface: #161b22;
  --color-surface-hover: #21262d;
  --color-border: #30363d;
  --color-text-primary: #e6edf3;
  --color-text-secondary: #8b949e;
  --color-text-muted: #6e7681;
  --color-success: #3fb950;
  --color-warning: #d29922;
  --color-error: #f85149;

  /* Spacing (8px grid) */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.5rem;    /* 24px */
  --space-6: 2rem;      /* 32px */
  --space-7: 2.5rem;    /* 40px */
  --space-8: 3rem;      /* 48px */
  --space-9: 4rem;      /* 64px */
  --space-10: 5rem;     /* 80px */

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --font-family-heading: 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;    /* 20px */
  --font-size-2xl: 1.5rem;    /* 24px */
  --font-size-3xl: 1.875rem;  /* 30px */
  --font-size-4xl: 2.25rem;   /* 36px */
  --font-size-5xl: 3rem;      /* 48px */
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

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

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.6);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;

  /* Layout */
  --container-max-width: 1200px;
  --header-height: 64px;
  --sidebar-width: 240px;

  /* Z-index scale */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-fixed: 300;
  --z-modal-backdrop: 400;
  --z-modal: 500;
  --z-tooltip: 600;
}

/* Light theme support */
[data-theme="light"] {
  --color-background: #f6f8fa;
  --color-surface: #ffffff;
  --color-surface-hover: #f3f4f6;
  --color-border: #d0d7de;
  --color-text-primary: #1f2328;
  --color-text-secondary: #656d76;
  --color-text-muted: #8c959f;
}