:root {
  /* Common System Metrics & Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  
  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
  --radius-full: 9999px;

  --container-max: 1200px;
  --header-height: 68px;
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 350ms cubic-bezier(0.175, 0.885, 0.32, 1.275);

  /* Status & Brand Accents */
  --accent-emerald: #10b981;
  --accent-emerald-subtle: rgba(16, 185, 129, 0.12);
  --accent-amber: #f59e0b;
  --accent-amber-subtle: rgba(245, 158, 11, 0.12);
  --accent-red: #ef4444;
  --accent-red-subtle: rgba(239, 68, 68, 0.12);
  --accent-blue: #3b82f6;
  --accent-blue-subtle: rgba(59, 130, 246, 0.14);
  --accent-purple: #8b5cf6;
  --accent-purple-subtle: rgba(139, 92, 246, 0.14);
  --accent-cyan: #06b6d4;
  --accent-cyan-subtle: rgba(6, 182, 212, 0.14);
}

/* Dark Theme (Default) */
:root,
:root[data-theme="dark"] {
  --bg-canvas: #090d16;
  --bg-subtle: #0f1420;
  --bg-surface: #141b2a;
  --bg-surface-hover: #1a2336;
  --bg-elevated: #1e293d;
  --bg-card: rgba(20, 27, 42, 0.75);
  
  --border-color: #202b3f;
  --border-color-subtle: #172030;
  --border-color-focus: #3b82f6;
  --border-glass: rgba(255, 255, 255, 0.08);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --brand-primary: #3b82f6;
  --brand-primary-hover: #60a5fa;
  --brand-glow: rgba(59, 130, 246, 0.2);

  --card-shadow: 0 4px 20px -2px rgba(0, 0, 0, 0.5), 0 0 0 1px var(--border-color);
  --elevated-shadow: 0 14px 34px -4px rgba(0, 0, 0, 0.7), 0 0 0 1px var(--border-color);

  --nav-bg: rgba(9, 13, 22, 0.85);
  --code-highlight-bg: #1e293b;
  --modal-backdrop: rgba(0, 0, 0, 0.82);
}

/* Light Theme */
:root[data-theme="light"] {
  --bg-canvas: #f8fafc;
  --bg-subtle: #f1f5f9;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f8fafc;
  --bg-elevated: #ffffff;
  --bg-card: rgba(255, 255, 255, 0.85);
  
  --border-color: #e2e8f0;
  --border-color-subtle: #edf2f7;
  --border-color-focus: #2563eb;
  --border-glass: rgba(0, 0, 0, 0.06);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;

  --brand-primary: #2563eb;
  --brand-primary-hover: #1d4ed8;
  --brand-glow: rgba(37, 99, 235, 0.1);

  --card-shadow: 0 4px 14px -2px rgba(15, 23, 42, 0.06), 0 0 0 1px var(--border-color);
  --elevated-shadow: 0 12px 28px -4px rgba(15, 23, 42, 0.1), 0 0 0 1px var(--border-color);

  --nav-bg: rgba(248, 250, 252, 0.85);
  --code-highlight-bg: #f1f5f9;
  --modal-backdrop: rgba(15, 23, 42, 0.75);
}