/* ============================================
   StudyHub - Design System Variables
   Inspired by Universal Tools Reference
   ============================================ */

:root {
  /* === Brand Color - Professional Blue === */
  --color-brand: #3b82f6;
  --color-brand-hover: #2563eb;
  --color-brand-light: #eff6ff;
  --color-brand-dark: #1e3a8a;

  /* === Category Colors (for icons only) === */
  --color-pdf: #ef4444;
  /* Red */
  --color-text: #8b5cf6;
  /* Purple */
  --color-math: #3b82f6;
  /* Blue */
  --color-productivity: #f97316;
  /* Orange */
  --color-convert: #10b981;
  /* Green */

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

  /* === Light Mode (Default) === */
  --bg-body: #f9fafb;
  --bg-body-rgb: 249, 250, 251;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f3f4f6;
  --bg-elevated: #ffffff;
  --bg-muted: #f3f4f6;

  --text-primary: #111827;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;

  --border-color: #e5e7eb;
  --border-color-hover: #d1d5db;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

  /* === Spacing === */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* === Typography === */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;

  /* === Border Radius === */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1rem;
  --radius-full: 9999px;

  /* === Transitions === */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease-in-out;

  /* === Z-Index === */
  --z-sticky: 50;
  --z-modal: 100;
}

/* === Dark Mode === */
[data-theme="dark"] {
  --bg-body: #0f1117;
  --bg-body-rgb: 15, 17, 23;
  --bg-surface: #1f2937;
  --bg-surface-hover: #374151;
  --bg-elevated: #1f2937;
  --bg-muted: rgba(31, 41, 55, 0.5);

  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;

  --border-color: #374151;
  --border-color-hover: #4b5563;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
}