:root {
  /* Colors: Neutral & High-Contrast Light Theme */
  --bg-primary: #F8FAFC;
  --bg-surface: #FFFFFF;
  --bg-surface-elevated: #FFFFFF;
  --bg-subtle: #F1F5F9;
  --bg-muted: #E2E8F0;
  
  /* Text Colors */
  --text-primary: #0F172A;     /* Deep slate for crisp readability */
  --text-secondary: #334155;   /* Neutral slate */
  --text-muted: #64748B;       /* Secondary details & captions */
  --text-subtle: #94A3B8;      /* Borders & disabled indicators */
  
  /* Accent Colors: Restrained Technical Cobalt & Indigo */
  --accent-primary: #2563EB;   /* Primary technical blue */
  --accent-hover: #1D4ED8;     /* Darker blue for interactions */
  --accent-subtle: #EFF6FF;    /* Light blue tint for tags and badges */
  --accent-border: #BFDBFE;    /* Soft blue border */
  
  /* Security & Status Accents */
  --security-accent: #0D9488;  /* Subtle teal for security/crypto topics */
  --security-bg: #F0FDFA;
  --security-border: #99F6E4;
  
  --status-active-bg: #ECFDF5;
  --status-active-text: #047857;
  --status-active-dot: #10B981;
  
  --status-planned-bg: #FFFBEB;
  --status-planned-text: #B45309;
  --status-planned-dot: #F59E0B;

  /* Borders & Dividers */
  --border-light: #E2E8F0;
  --border-subtle: #CBD5E1;
  --border-focus: #3B82F6;
  
  /* Header Glass */
  --header-bg: rgba(248, 250, 252, 0.9);
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  
  /* Spacing */
  --space-2xs: 0.25rem;  /* 4px */
  --space-xs: 0.5rem;    /* 8px */
  --space-sm: 0.75rem;   /* 12px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  --space-3xl: 4.5rem;   /* 72px */
  --space-4xl: 6rem;     /* 96px */
  
  /* Layout */
  --max-width-content: 1120px;
  --max-width-narrow: 780px;
  --header-height: 4.25rem;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(15, 23, 42, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.07), 0 2px 4px -2px rgba(15, 23, 42, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(15, 23, 42, 0.08), 0 4px 6px -4px rgba(15, 23, 42, 0.04);
  --shadow-card: 0 1px 3px rgba(15, 23, 42, 0.06), 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-card-hover: 0 8px 20px -4px rgba(15, 23, 42, 0.09), 0 3px 6px -2px rgba(15, 23, 42, 0.04);

  /* Transitions */
  --transition-fast: 0.18s ease;
  --transition-normal: 0.25s ease;
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

/* 2. Dark Mode Theme System */
[data-theme="dark"] {
  /* Page & Surface Colors */
  --bg-primary: #0B0F14;          /* Deep neutral dark */
  --bg-surface: #111822;          /* Card & elevated surface */
  --bg-surface-elevated: #151E2B; /* Lifted surface */
  --bg-subtle: #16202D;           /* Badges, tags, and pills */
  --bg-muted: #1E2B3C;            /* Dark dividers & borders */
  
  /* Text Colors */
  --text-primary: #F3F4F6;        /* High-contrast crisp light text */
  --text-secondary: #A7B0BC;      /* Muted cool gray for paragraphs */
  --text-muted: #828E9E;          /* Secondary captions & meta */
  --text-subtle: #4B5868;         /* Subtle borders & disabled indicators */
  
  /* Accent Colors: High Contrast Technical Blue */
  --accent-primary: #3B82F6;      /* High contrast bright blue */
  --accent-hover: #60A5FA;        /* Bright blue hover */
  --accent-subtle: rgba(59, 130, 246, 0.12); /* Soft blue tint */
  --accent-border: rgba(59, 130, 246, 0.32); /* Readable blue border */
  
  /* Security & Status Accents */
  --security-accent: #2DD4BF;     /* Readable teal */
  --security-bg: rgba(45, 212, 191, 0.1);
  --security-border: rgba(45, 212, 191, 0.28);
  
  --status-active-bg: rgba(16, 185, 129, 0.12);
  --status-active-text: #34D399;
  --status-active-dot: #10B981;
  
  --status-planned-bg: rgba(245, 158, 11, 0.12);
  --status-planned-text: #FBBF24;
  --status-planned-dot: #F59E0B;

  /* Borders & Dividers */
  --border-light: #202B39;        /* Subtle dark card & section border */
  --border-subtle: #2D3C4E;       /* Card hover border */
  --border-focus: #60A5FA;
  
  /* Header Glass */
  --header-bg: rgba(11, 15, 20, 0.88);
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.35);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.45), 0 2px 4px -2px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.4), 0 1px 2px rgba(0, 0, 0, 0.25);
  --shadow-card-hover: 0 8px 20px -4px rgba(0, 0, 0, 0.55), 0 3px 6px -2px rgba(0, 0, 0, 0.35);
}