:root {
  /* Brand Palette */
  --color-primary: #1e40af;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-primary-dark: #1e3a8a;
  
  --color-secondary: #475569;
  --color-secondary-hover: #334155;
  --color-secondary-light: #f1f5f9;

  --color-accent: #0d9488;
  --color-accent-hover: #0f766e;
  --color-accent-light: #ccfbf1;

  /* Semantic Palette */
  --color-success: #15803d;
  --color-success-hover: #166534;
  --color-success-bg: #dcfce7;
  --color-success-border: #bbf7d0;

  --color-warning: #b45309;
  --color-warning-hover: #92400e;
  --color-warning-bg: #fef3c7;
  --color-warning-border: #fde68a;

  --color-danger: #b91c1c;
  --color-danger-hover: #991b1b;
  --color-danger-bg: #fee2e2;
  --color-danger-border: #fecaca;

  --color-info: #0369a1;
  --color-info-hover: #075985;
  --color-info-bg: #e0f2fe;
  --color-info-border: #bae6fd;

  /* Neutrals & Surfaces */
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-surface-hover: #f8fafc;
  --color-surface-alt: #f1f5f9;
  
  --color-border: #e2e8f0;
  --color-border-dark: #cbd5e1;
  --color-border-focus: #3b82f6;

  --color-text-main: #0f172a;
  --color-text-muted: #64748b;
  --color-text-light: #94a3b8;
  --color-text-inverse: #ffffff;

  /* Typography */
  --font-family-base: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  --font-family-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  
  --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-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  --line-height-tight: 1.25;
  --line-height-base: 1.5;
  --line-height-relaxed: 1.625;

  /* Spacing */
  --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 */

  /* Border Radii */
  --radius-sm: 0.25rem;  /* 4px */
  --radius-md: 0.375rem; /* 6px */
  --radius-lg: 0.5rem;   /* 8px */
  --radius-xl: 0.75rem;  /* 12px */
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Layout dimensions */
  --sidebar-width: 260px;
  --header-height: 64px;
  --bottom-nav-height: 60px;
  --touch-target-min: 44px;

  /* Layering / Z-Index */
  --z-base: 1;
  --z-header: 100;
  --z-bottom-nav: 200;
  --z-sidebar: 300;
  --z-modal-backdrop: 400;
  --z-modal: 500;
  --z-toast: 1000;
}