/* ============================================================
   CSS Design Tokens - Single Source of Truth
   ============================================================ */

:root {
  /* ========== Primary Colors ========== */
  --color-primary: #667eea;
  --color-secondary: #764ba2;
  --color-accent: #00d4ff;

  /* ========== Semantic Colors ========== */
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;
  --color-danger: #ef4444;

  /* ========== Gradients ========== */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-primary-vertical: linear-gradient(180deg, #764ba2 0%, #667eea 100%);
  --gradient-primary-vertical-hover: linear-gradient(180deg, #764ba2 0%, #6f7ef0 65%, #6f7ef0 100%);
  --gradient-primary-horizontal: linear-gradient(90deg, #667eea, #764ba2);
  --gradient-text: linear-gradient(135deg, #8197f7 0%, #9d6ece 100%);
  --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
  --gradient-accent: linear-gradient(135deg, #00d4ff 0%, #667eea 100%);
  --gradient-dark: linear-gradient(180deg, #0a0a0a 0%, #1a1a2e 100%);
  --gradient-card: linear-gradient(145deg, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0.02) 100%);

  /* ========== Backgrounds - General ========== */
  --bg-dark: #0a0a0a;
  --bg-darker: #0d0d0d;
  --bg-dark-alt: #1a1a1a;
  --bg-dark-subtle: #111111;
  --bg-dark-muted: #121212;
  --bg-card: rgba(255, 255, 255, 0.03);
  --bg-card-hover: rgba(255, 255, 255, 0.05);
  --bg-overlay: rgba(0, 0, 0, 0.8);

  /* ========== Backgrounds - App Specific ========== */
  --bg-app: #0a0b0d;
  --bg-sidebar: #161D26;
  --bg-sidebar-dark: #131920;
  --bg-input: #1E2631;
  --bg-hover: rgba(255, 255, 255, 0.03);
  --bg-hover-strong: rgba(255, 255, 255, 0.1);
  --bg-modal: rgba(0, 0, 0, 0.97);
  --gradient-scrollbar: linear-gradient(to bottom, #1E2631, #131920);
  --gradient-sidebar: linear-gradient(to bottom, #161D26 0%, #131920 100%);
  --gradient-sidebar-reverse: linear-gradient(to bottom, #131920 0%, #161D26 100%);

  /* ========== Backgrounds - Semantic ========== */
  --bg-danger: rgba(239, 68, 68, 0.1);
  --bg-danger-hover: rgba(239, 68, 68, 0.15);

  /* ========== Text Colors ========== */
  --text-primary: #ffffff;
  --text-secondary: #e0e0e0;
  --text-muted: #9ca3af;
  --text-dim: #b0b0b0;
  --text-placeholder: rgba(226, 227, 224, 0.4);
  --text-gray: #a0a0a0;

  /* ========== Borders ========== */
  --border-subtle: rgba(255, 255, 255, 0.05);
  --border-light: rgba(255, 255, 255, 0.1);
  --border-medium: rgba(255, 255, 255, 0.2);
  --border-dark: #333;

  /* ========== Shadows ========== */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.5);
  --shadow-card: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-soft: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-elevated: 0 30px 60px rgba(0, 0, 0, 0.9);
  --shadow-primary: 0 4px 20px rgba(102, 126, 234, 0.3);
  --shadow-primary-hover: 0 6px 25px rgba(102, 126, 234, 0.4);
  --shadow-primary-lg: 0 8px 30px rgba(102, 126, 234, 0.4);

  /* ========== Spacing ========== */
  --space-xs: 0.25rem;   /* 4px */
  --space-sm: 0.5rem;    /* 8px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  --space-3xl: 4rem;     /* 64px */

  /* ========== Border Radius ========== */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;

  /* ========== Transitions ========== */
  --transition-fast: 0.15s ease;
  --transition-base: 0.2s ease;
  --transition-slow: 0.3s ease;

  /* ========== Typography ========== */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --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: 2rem;      /* 32px */
  --font-size-4xl: 2.5rem;    /* 40px */

  /* ========== Z-Index Scale ========== */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-navbar: 1000;
  --z-modal-backdrop: 1100;
  --z-modal: 1200;
  --z-tooltip: 1300;
  --z-toast: 1400;

  /* ========== Light Theme (About Page) ========== */
  --light-bg: #fafafa;
  --light-bg-white: #ffffff;
  --light-bg-gray: #f7fafc;
  --light-text-dark: #1a202c;
  --light-text-body: #2d3748;
  --light-text-muted: #4a5568;
  --light-text-gray: #718096;
  --light-border: #e2e8f0;
  --light-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);

  /* ========== Agreement/Login Theme ========== */
  --color-blue: #3b82f6;
  --color-purple: #8b5cf6;
  --gradient-blue-purple: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
}

/* Animatable CSS Custom Properties */
@property --gradient-angle {
  syntax: '<angle>';
  initial-value: 140deg;
  inherits: false;
}