/* ==========================================================================
   Alternivite Design System — CSS Custom Properties
   Color palette, semantic tokens, typography, spacing, shadows, z-index
   ========================================================================== */

:root {
   /* --------------------------------------------------------------------------
      COLOR PALETTE — Light Mode
      Primary: Indigo (AI/Innovation)
      Secondary: Violet (Premium/Creative)
      Accent: Cyan (Tech/Modern)
      Success: Emerald (Trust/Compliance)
      Warning: Amber (Attention)
      Error: Rose (Alerts)
      Neutral: Slate (UI chrome)
      -------------------------------------------------------------------------- */

   /* Brand — Primary (Indigo) */
   --color-primary-50: #eef2ff;
   --color-primary-100: #e0e7ff;
   --color-primary-200: #c7d2fe;
   --color-primary-300: #a5b4fc;
   --color-primary-400: #818cf8;
   --color-primary-500: #6366f1;
   --color-primary-600: #4f46e5;
   --color-primary-700: #4338ca;
   --color-primary-800: #3730a3;
   --color-primary-900: #312e81;
   --color-primary-950: #1e1b4b;

   /* Brand — Secondary (Violet) */
   --color-secondary-50: #f5f3ff;
   --color-secondary-100: #ede9fe;
   --color-secondary-200: #ddd6fe;
   --color-secondary-300: #c4b5fd;
   --color-secondary-400: #a78bfa;
   --color-secondary-500: #8b5cf6;
   --color-secondary-600: #7c3aed;
   --color-secondary-700: #6d28d9;
   --color-secondary-800: #5b21b6;
   --color-secondary-900: #4c1d95;
   --color-secondary-950: #2e1065;

   /* Accent (Cyan) */
   --color-accent-50: #ecfeff;
   --color-accent-100: #cffafe;
   --color-accent-200: #a5f3fc;
   --color-accent-300: #67e8f9;
   --color-accent-400: #22d3ee;
   --color-accent-500: #06b6d4;
   --color-accent-600: #0891b2;
   --color-accent-700: #0e7490;
   --color-accent-800: #155e75;
   --color-accent-900: #164e63;
   --color-accent-950: #083344;

   /* Success (Emerald) */
   --color-success-50: #ecfdf5;
   --color-success-100: #d1fae5;
   --color-success-200: #a7f3d0;
   --color-success-300: #6ee7b7;
   --color-success-400: #34d399;
   --color-success-500: #10b981;
   --color-success-600: #059669;
   --color-success-700: #047857;
   --color-success-800: #065f46;
   --color-success-900: #064e3b;
   --color-success-950: #022c22;

   /* Warning (Amber) */
   --color-warning-50: #fffbeb;
   --color-warning-100: #fef3c7;
   --color-warning-200: #fde68a;
   --color-warning-300: #fcd34d;
   --color-warning-400: #fbbf24;
   --color-warning-500: #f59e0b;
   --color-warning-600: #d97706;
   --color-warning-700: #b45309;
   --color-warning-800: #92400e;
   --color-warning-900: #78350f;
   --color-warning-950: #451a03;

   /* Error (Rose) */
   --color-error-50: #fff1f2;
   --color-error-100: #ffe4e6;
   --color-error-200: #fecdd3;
   --color-error-300: #fda4af;
   --color-error-400: #fb7185;
   --color-error-500: #f43f5e;
   --color-error-600: #e11d48;
   --color-error-700: #be123c;
   --color-error-800: #9f1239;
   --color-error-900: #881337;
   --color-error-950: #4c0519;

   /* Neutral (Slate) */
   --color-neutral-50: #f8fafc;
   --color-neutral-100: #f1f5f9;
   --color-neutral-200: #e2e8f0;
   --color-neutral-300: #cbd5e1;
   --color-neutral-400: #94a3b8;
   --color-neutral-500: #64748b;
   --color-neutral-600: #475569;
   --color-neutral-700: #334155;
   --color-neutral-800: #1e293b;
   --color-neutral-900: #0f172a;
   --color-neutral-950: #020617;

   /* --------------------------------------------------------------------------
      SEMANTIC TOKENS — Light Mode
      -------------------------------------------------------------------------- */

   /* Backgrounds */
   --bg-primary: #ffffff;
   --bg-secondary: var(--color-neutral-50);
   --bg-tertiary: var(--color-neutral-100);
   --bg-inverse: var(--color-neutral-900);
   --bg-brand: var(--color-primary-500);
   --bg-brand-subtle: var(--color-primary-50);
   --bg-success-subtle: var(--color-success-50);
   --bg-warning-subtle: var(--color-warning-50);
   --bg-error-subtle: var(--color-error-50);

   /* Text / Foreground */
   --text-primary: var(--color-neutral-900);
   --text-secondary: var(--color-neutral-600);
   --text-tertiary: var(--color-neutral-500);
   --text-inverse: #ffffff;
   --text-brand: var(--color-primary-600);
   --text-brand-strong: var(--color-primary-700);
   --text-success: var(--color-success-700);
   --text-warning: var(--color-warning-700);
   --text-error: var(--color-error-700);

   /* Borders */
   --border-primary: var(--color-neutral-200);
   --border-secondary: var(--color-neutral-100);
   --border-focus: var(--color-primary-500);
   --border-success: var(--color-success-500);
   --border-warning: var(--color-warning-500);
   --border-error: var(--color-error-500);

   /* Interactive */
   --interactive-primary: var(--color-primary-600);
   --interactive-primary-hover: var(--color-primary-700);
   --interactive-primary-active: var(--color-primary-800);
   --interactive-secondary: var(--color-neutral-100);
   --interactive-secondary-hover: var(--color-neutral-200);
   --interactive-secondary-active: var(--color-neutral-300);

   /* Overlay */
   --overlay-bg: rgba(15, 23, 42, 0.5);
   --overlay-bg-heavy: rgba(15, 23, 42, 0.8);

   /* --------------------------------------------------------------------------
      TYPOGRAPHY
      -------------------------------------------------------------------------- */

   /* Font Stacks */
   --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
   --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Consolas', monospace;

   /* Font Sizes — Modular scale (1.25) */
   --text-xs: 0.75rem;       /* 12px */
   --text-sm: 0.875rem;      /* 14px */
   --text-base: 1rem;        /* 16px */
   --text-lg: 1.125rem;      /* 18px */
   --text-xl: 1.25rem;       /* 20px */
   --text-2xl: 1.5rem;       /* 24px */
   --text-3xl: 1.875rem;     /* 30px */
   --text-4xl: 2.25rem;      /* 36px */
   --text-5xl: 3rem;         /* 48px */
   --text-6xl: 3.75rem;      /* 60px */
   --text-7xl: 4.5rem;       /* 72px */

   /* Font Weights */
   --font-regular: 400;
   --font-medium: 500;
   --font-semibold: 600;
   --font-bold: 700;
   --font-extrabold: 800;

   /* Line Heights */
   --leading-none: 1;
   --leading-tight: 1.25;
   --leading-snug: 1.375;
   --leading-normal: 1.5;
   --leading-relaxed: 1.625;
   --leading-loose: 2;

   /* Letter Spacing */
   --tracking-tighter: -0.05em;
   --tracking-tight: -0.025em;
   --tracking-normal: 0;
   --tracking-wide: 0.025em;
   --tracking-wider: 0.05em;
   --tracking-widest: 0.1em;

   /* --------------------------------------------------------------------------
      SPACING
      -------------------------------------------------------------------------- */

   --space-0: 0;
   --space-px: 1px;
   --space-0-5: 0.125rem;    /* 2px */
   --space-1: 0.25rem;       /* 4px */
   --space-1-5: 0.375rem;    /* 6px */
   --space-2: 0.5rem;        /* 8px */
   --space-2-5: 0.625rem;    /* 10px */
   --space-3: 0.75rem;       /* 12px */
   --space-3-5: 0.875rem;    /* 14px */
   --space-4: 1rem;          /* 16px */
   --space-5: 1.25rem;       /* 20px */
   --space-6: 1.5rem;        /* 24px */
   --space-7: 1.75rem;       /* 28px */
   --space-8: 2rem;          /* 32px */
   --space-9: 2.25rem;       /* 36px */
   --space-10: 2.5rem;       /* 40px */
   --space-12: 3rem;         /* 48px */
   --space-14: 3.5rem;       /* 56px */
   --space-16: 4rem;         /* 64px */
   --space-20: 5rem;         /* 80px */
   --space-24: 6rem;         /* 96px */
   --space-28: 7rem;         /* 112px */
   --space-32: 8rem;         /* 128px */

   /* --------------------------------------------------------------------------
      BORDER RADIUS
      -------------------------------------------------------------------------- */

   --radius-none: 0;
   --radius-sm: 0.25rem;     /* 4px */
   --radius-md: 0.375rem;    /* 6px */
   --radius-lg: 0.5rem;      /* 8px */
   --radius-xl: 0.75rem;     /* 12px */
   --radius-2xl: 1rem;       /* 16px */
   --radius-3xl: 1.5rem;     /* 24px */
   --radius-full: 9999px;

   /* --------------------------------------------------------------------------
      SHADOWS
      -------------------------------------------------------------------------- */

   --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
   --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
   --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
   --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
   --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
   --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
   --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.05);

   /* Brand Shadows */
   --shadow-brand: 0 4px 14px 0 rgba(99, 102, 241, 0.39);
   --shadow-brand-lg: 0 10px 40px 0 rgba(99, 102, 241, 0.3);
   --shadow-success: 0 4px 14px 0 rgba(16, 185, 129, 0.39);
   --shadow-error: 0 4px 14px 0 rgba(244, 63, 94, 0.39);

   /* --------------------------------------------------------------------------
      TRANSITIONS
      -------------------------------------------------------------------------- */

   --duration-fast: 100ms;
   --duration-normal: 200ms;
   --duration-slow: 300ms;
   --duration-slower: 500ms;

   --ease-default: cubic-bezier(0.4, 0, 0.2, 1);
   --ease-in: cubic-bezier(0.4, 0, 1, 1);
   --ease-out: cubic-bezier(0, 0, 0.2, 1);
   --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
   --ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);

   /* --------------------------------------------------------------------------
      Z-INDEX SCALE
      -------------------------------------------------------------------------- */

   --z-behind: -1;
   --z-base: 0;
   --z-raised: 10;
   --z-dropdown: 100;
   --z-sticky: 200;
   --z-overlay: 300;
   --z-modal: 400;
   --z-popover: 500;
   --z-toast: 600;
   --z-max: 9999;

   /* --------------------------------------------------------------------------
      LAYOUT CONSTANTS
      -------------------------------------------------------------------------- */

   --container-sm: 640px;
   --container-md: 768px;
   --container-lg: 1024px;
   --container-xl: 1280px;
   --container-2xl: 1440px;

   --nav-height: 4rem;
   --nav-height-scrolled: 3.5rem;

   /* Breakpoints (reference only — use in @media)
      --bp-sm: 640px
      --bp-md: 768px
      --bp-lg: 1024px
      --bp-xl: 1280px
      --bp-2xl: 1536px */
}

/* ==========================================================================
   DARK MODE — Explicit [data-theme="dark"]
   ========================================================================== */

[data-theme="dark"] {
   /* Backgrounds */
   --bg-primary: var(--color-neutral-900);
   --bg-secondary: var(--color-neutral-800);
   --bg-tertiary: var(--color-neutral-700);
   --bg-inverse: #ffffff;
   --bg-brand: var(--color-primary-600);
   --bg-brand-subtle: rgba(99, 102, 241, 0.15);
   --bg-success-subtle: rgba(16, 185, 129, 0.15);
   --bg-warning-subtle: rgba(245, 158, 11, 0.15);
   --bg-error-subtle: rgba(244, 63, 94, 0.15);

   /* Text */
   --text-primary: var(--color-neutral-50);
   --text-secondary: var(--color-neutral-400);
   --text-tertiary: var(--color-neutral-500);
   --text-inverse: var(--color-neutral-900);
   --text-brand: var(--color-primary-400);
   --text-brand-strong: var(--color-primary-300);
   --text-success: var(--color-success-400);
   --text-warning: var(--color-warning-400);
   --text-error: var(--color-error-400);

   /* Borders */
   --border-primary: var(--color-neutral-700);
   --border-secondary: var(--color-neutral-800);
   --border-focus: var(--color-primary-500);
   --border-success: var(--color-success-500);
   --border-warning: var(--color-warning-500);
   --border-error: var(--color-error-500);

   /* Interactive */
   --interactive-primary: var(--color-primary-500);
   --interactive-primary-hover: var(--color-primary-400);
   --interactive-primary-active: var(--color-primary-300);
   --interactive-secondary: var(--color-neutral-800);
   --interactive-secondary-hover: var(--color-neutral-700);
   --interactive-secondary-active: var(--color-neutral-600);

   /* Overlay */
   --overlay-bg: rgba(0, 0, 0, 0.6);
   --overlay-bg-heavy: rgba(0, 0, 0, 0.8);

   /* Shadows (deeper for dark backgrounds) */
   --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
   --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.4), 0 1px 2px -1px rgba(0, 0, 0, 0.3);
   --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
   --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
   --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
   --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.6);
   --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.3);
   --shadow-brand: 0 4px 14px 0 rgba(99, 102, 241, 0.25);
   --shadow-brand-lg: 0 10px 40px 0 rgba(99, 102, 241, 0.2);
   --shadow-success: 0 4px 14px 0 rgba(16, 185, 129, 0.25);
   --shadow-error: 0 4px 14px 0 rgba(244, 63, 94, 0.25);
}

/* ==========================================================================
   SYSTEM DARK MODE — Auto-detect via prefers-color-scheme
   Only applies when no explicit [data-theme] attribute is set
   ========================================================================== */

@media (prefers-color-scheme: dark) {
   :root:not([data-theme="light"]) {
      --bg-primary: var(--color-neutral-900);
      --bg-secondary: var(--color-neutral-800);
      --bg-tertiary: var(--color-neutral-700);
      --bg-inverse: #ffffff;
      --bg-brand: var(--color-primary-600);
      --bg-brand-subtle: rgba(99, 102, 241, 0.15);
      --bg-success-subtle: rgba(16, 185, 129, 0.15);
      --bg-warning-subtle: rgba(245, 158, 11, 0.15);
      --bg-error-subtle: rgba(244, 63, 94, 0.15);

      --text-primary: var(--color-neutral-50);
      --text-secondary: var(--color-neutral-400);
      --text-tertiary: var(--color-neutral-500);
      --text-inverse: var(--color-neutral-900);
      --text-brand: var(--color-primary-400);
      --text-brand-strong: var(--color-primary-300);
      --text-success: var(--color-success-400);
      --text-warning: var(--color-warning-400);
      --text-error: var(--color-error-400);

      --border-primary: var(--color-neutral-700);
      --border-secondary: var(--color-neutral-800);
      --border-focus: var(--color-primary-500);
      --border-success: var(--color-success-500);
      --border-warning: var(--color-warning-500);
      --border-error: var(--color-error-500);

      --interactive-primary: var(--color-primary-500);
      --interactive-primary-hover: var(--color-primary-400);
      --interactive-primary-active: var(--color-primary-300);
      --interactive-secondary: var(--color-neutral-800);
      --interactive-secondary-hover: var(--color-neutral-700);
      --interactive-secondary-active: var(--color-neutral-600);

      --overlay-bg: rgba(0, 0, 0, 0.6);
      --overlay-bg-heavy: rgba(0, 0, 0, 0.8);

      --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
      --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.4), 0 1px 2px -1px rgba(0, 0, 0, 0.3);
      --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
      --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
      --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
      --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.6);
      --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.3);
      --shadow-brand: 0 4px 14px 0 rgba(99, 102, 241, 0.25);
      --shadow-brand-lg: 0 10px 40px 0 rgba(99, 102, 241, 0.2);
      --shadow-success: 0 4px 14px 0 rgba(16, 185, 129, 0.25);
      --shadow-error: 0 4px 14px 0 rgba(244, 63, 94, 0.25);
   }
}