/* ============================================
   EduCRS Flashcards — Design Tokens
   Strict monochrome theming
   ============================================ */

:root {
  /* Colors - Light Theme */
  --bg-primary: #ffffff;
  --bg-secondary: #fafafa;
  --bg-surface: #f2f2f2;
  --bg-surface-hover: #e8e8e8;
  --bg-surface-active: #dedede;
  --bg-overlay: rgba(0, 0, 0, 0.4);

  --text-primary: #000000;
  --text-secondary: #4a4a4a;
  --text-tertiary: #8a8a8a;
  --text-placeholder: #b0b0b0;

  --border: #e5e5e5;
  --border-strong: #cccccc;
  --border-subtle: #f0f0f0;

  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.12);

  /* Spacing */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
  --radius-full: 9999px;

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
  --dur-fast: 150ms;
  --dur-normal: 250ms;
  --dur-slow: 400ms;

  /* Layout */
  --sidebar-width: 280px;
  --header-height: 60px;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --fs-xs: 0.75rem;
  --fs-sm: 0.8125rem;
  --fs-base: 0.9375rem;
  --fs-md: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.25rem;
  --fs-2xl: 1.5rem;
  --fs-3xl: 2rem;
  --fs-4xl: 2.5rem;
  --fw-light: 300;
  --fw-normal: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;
}

[data-theme="dark"] {
  --bg-primary: #000000;
  --bg-secondary: #080808;
  --bg-surface: #121212;
  --bg-surface-hover: #1a1a1a;
  --bg-surface-active: #242424;
  --bg-overlay: rgba(0, 0, 0, 0.6);

  --text-primary: #ffffff;
  --text-secondary: #b0b0b0;
  --text-tertiary: #707070;
  --text-placeholder: #505050;

  --border: #1e1e1e;
  --border-strong: #333333;
  --border-subtle: #141414;

  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.6);
}