:root {
  color-scheme: dark;
  /* Surface & Background (Pure Black Theme) */
  --color-bg: #000000;
  --color-surface: #000000;
  --color-surface-el: #0A0A0A;
  --color-surface-hover: #141414;
  --color-surface-active: #1F1F1F;

  /* Borders & Dividers */
  --color-border: #222222;
  --color-border-light: #181818;
  --color-border-subtle: rgba(255, 255, 255, 0.08);

  /* Typography */
  --color-text-primary: #FAFAFA;
  --color-text-secondary: #A3A3A3;
  --color-text-muted: #737373;
  --color-text-inverse: #000000;

  /* Brand Accents */
  --color-primary: #E0291D;
  --color-primary-hover: #FF3B2F;
  --color-primary-dim: rgba(224, 41, 29, 0.15);
  --color-primary-glow: rgba(224, 41, 29, 0.35);
  --color-secondary: #FAFAFA;

  /* Functional Semantic Statuses */
  --color-success: #10B981;
  --color-success-dim: rgba(16, 185, 129, 0.15);
  --color-warning: #F59E0B;
  --color-warning-dim: rgba(245, 158, 11, 0.15);
  --color-danger: #EF4444;
  --color-danger-dim: rgba(239, 68, 68, 0.15);
  --color-info: #0284C7;
  --color-info-dim: rgba(2, 132, 199, 0.15);

  /* Schedule Specific Semantic States */
  --status-on-track: #10B981;
  --status-in-progress: #0284C7;
  --status-completed: #6366F1;
  --status-at-risk: #F59E0B;
  --status-delayed: #EF4444;
  --status-pending-review: #EAB308;
  --status-ambiguous: #F97316;
  --status-unmatched: #EC4899;
  --status-rejected: #991B1B;
  --status-syncing: #38BDF8;
  --status-offline: #F59E0B;
  --status-sync-failed: #EF4444;

  /* Typography Scale */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "Cascadia Code", "Source Code Pro", Menlo, Monaco, Consolas, monospace;

  --text-xs: 0.75rem;    /* 12px */
  --text-sm: 0.8125rem;  /* 13px */
  --text-base: 0.875rem; /* 14px */
  --text-md: 1rem;       /* 16px */
  --text-lg: 1.125rem;   /* 18px */
  --text-xl: 1.25rem;    /* 20px */
  --text-2xl: 1.5rem;    /* 24px */
  --text-3xl: 1.875rem;  /* 30px */

  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  /* Spacing Scale (Base: 4px) */
  --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 */

  /* Borders & Radius */
  --radius-xs: 3px;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.35);
  --shadow-md: 0 4px 12px -1px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 10px 25px -3px rgba(0, 0, 0, 0.6);
  --shadow-glow: 0 0 15px rgba(224, 41, 29, 0.3);

  /* Layout Dimensions */
  --header-height: 56px;
  --sidebar-width: 250px;
  --sidebar-collapsed-width: 64px;
  --mobile-nav-height: 60px;
  --max-content-width: 1600px;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Z-Index Hierarchy */
  --z-base: 1;
  --z-sticky: 100;
  --z-header: 200;
  --z-drawer: 300;
  --z-modal: 400;
  --z-toast: 500;
}