/* =========================================================
   NET Prep Desk — design tokens
   Palette: ledger/admit-card academic, modernised with more
   depth, motion, and a responsive nav/footer system.
   ========================================================= */
:root {
  --paper: #FBF8F1;
  --paper-line: #E4DCC8;
  --ink: #14213D;
  --ink-soft: #3B4A6B;
  --gold: #B08D57;
  --gold-deep: #8C6D3F;
  --teal: #2F6F63;
  --red: #A13D3D;
  --card-bg: #FFFFFF;
  --radius: 8px;
  --radius-lg: 14px;
  --font-display: "Source Serif 4", "Georgia", serif;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", "Courier New", monospace;
  --shadow-card: 0 1px 2px rgba(20, 33, 61, 0.06), 0 6px 16px rgba(20, 33, 61, 0.07);
  --shadow-card-hover: 0 4px 10px rgba(20, 33, 61, 0.10), 0 14px 32px rgba(20, 33, 61, 0.12);
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink);
  line-height: 1.2;
  margin: 0 0 0.5em;
}

a { color: var(--gold-deep); }
a:hover { color: var(--ink); }

:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 2px;
}

.container { max-width: 1120px; margin: 0 auto; padding: 0 20px; }

/* ---------- Announcement banner (configurable, dismissible) ---------- */
.announcement {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 10px 12px;
}
.announcement--info { background: #EAF1EF; color: var(--teal); }
.announcement--success { background: #E8F3EA; color: #2F6F45; }
.announcement--warning { background: #FBF1DD; color: var(--gold-deep); }
.announcement-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  position: relative;
}
.announcement-message a { font-weight: 600; text-decoration: underline; }
.announcement-dismiss {
  position: absolute;
  right: 20px;
  background: none;
  border: none;
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
  color: inherit;
  opacity: 0.7;
}
.announcement-dismiss:hover { opacity: 1; }

/* ---------- Header / nav ---------- */
.disclaimer-strip {
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.02em;
  text-align: center;
  padding: 6px 12px;
}
.disclaimer-strip a { color: var(--gold); }

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  border-bottom: 2px solid var(--ink);
  background: rgba(251, 248, 241, 0.92);
  backdrop-filter: blur(6px);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  padding-bottom: 14px;
  gap: 16px;
}
.brand {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  text-decoration: none;
  color: var(--ink);
  flex-shrink: 0;
}
.brand .tag {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.62rem;
  color: var(--ink-soft);
  letter-spacing: 0.07em;
  text-transform: uppercase;
}
.main-nav { display: flex; gap: 20px; flex-wrap: wrap; flex: 1; justify-content: center; }
.main-nav a {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  text-decoration: none;
  color: var(--ink-soft);
  padding: 6px 2px;
  border-bottom: 2px solid transparent;
  transition: color 0.15s var(--ease), border-color 0.15s var(--ease);
}
.main-nav a:hover, .main-nav a.active {
  color: var(--ink);
  border-bottom-color: var(--gold);
}
.nav-cta { flex-shrink: 0; }
.nav-toggle {
  display: none;
  background: none;
  border: 2px solid var(--ink);
  border-radius: var(--radius);
  font-size: 1.1rem;
  padding: 4px 10px;
  cursor: pointer;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  text-decoration: none;
  padding: 12px 22px;
  border-radius: var(--radius);
  border: 2px solid var(--ink);
  cursor: pointer;
  background: transparent;
  color: var(--ink);
  transition: background 0.18s var(--ease), color 0.18s var(--ease), transform 0.15s var(--ease), box-shadow 0.18s var(--ease);
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 6px 16px rgba(20,33,61,0.15); }
.btn-primary { background: var(--ink); color: var(--paper); }
.btn-primary:hover { background: var(--gold-deep); border-color: var(--gold-deep); color: #fff; }
.btn-ghost:hover { background: var(--ink); color: var(--paper); }
.btn-sm { padding: 8px 16px; font-size: 0.75rem; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; box-shadow: none; }

/* ---------- Hero ---------- */
.hero {
  padding: 64px 0 44px;
  border-bottom: 1px solid var(--paper-line);
  background: linear-gradient(180deg, rgba(176,141,87,0.06), transparent 60%);
}
.hero h1 {
  font-size: clamp(2.1rem, 4.2vw, 3.2rem);
  max-width: 20ch;
}
.hero p.lead {
  max-width: 62ch;
  color: var(--ink-soft);
  font-size: 1.08rem;
}
.hero-actions { display: flex; gap: 14px; margin-top: 24px; flex-wrap: wrap; }

/* ---------- Section headings ---------- */
.section { padding: 44px 0; }
.section-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  border-bottom: 1px solid var(--paper-line);
  padding-bottom: 10px;
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 8px;
}
.section-heading h2 { font-size: 1.55rem; }
.section-heading .meta { font-family: var(--font-mono); font-size: 0.75rem; color: var(--ink-soft); }

/* ---------- Unit index-card / admit-card tabs ---------- */
.unit-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}
.unit-card {
  position: relative;
  background: var(--card-bg);
  border: 1px solid var(--paper-line);
  border-left: 6px solid var(--gold);
  border-radius: var(--radius-lg);
  padding: 20px 20px 18px 22px;
  text-decoration: none;
  color: var(--ink);
  box-shadow: var(--shadow-card);
  transition: transform 0.22s var(--ease), box-shadow 0.22s var(--ease), border-left-color 0.22s var(--ease);
  display: flex;
  flex-direction: column;
  gap: 9px;
}
.unit-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-card-hover); border-left-color: var(--teal); }
.unit-card.is-locked { opacity: 0.5; pointer-events: none; }
.unit-card .unit-no {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  color: var(--ink-soft);
  text-transform: uppercase;
}
.unit-card h3 { font-size: 1.18rem; margin: 0; }
.unit-card .unit-meta {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
}
.status-pill {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 3px 9px;
  border-radius: 999px;
  border: 1px solid currentColor;
  width: fit-content;
}
.status-published { color: var(--teal); }
.status-draft, .status-review { color: var(--gold-deep); }
.status-archived { color: var(--ink-soft); }

.progress-bar { height: 6px; background: var(--paper-line); border-radius: 3px; overflow: hidden; }
.progress-bar > span { display: block; height: 100%; background: linear-gradient(90deg, var(--gold), var(--gold-deep)); transition: width 0.3s var(--ease); }

/* ---------- Subject cards (Paper II) ---------- */
.subject-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 18px; }
.subject-card {
  background: linear-gradient(155deg, var(--ink), #1E2E52);
  color: var(--paper);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-decoration: none;
  display: block;
  box-shadow: var(--shadow-card);
  transition: transform 0.22s var(--ease), box-shadow 0.22s var(--ease);
}
.subject-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-card-hover); }
.subject-card .code { font-family: var(--font-mono); font-size: 0.7rem; color: var(--gold); }
.subject-card h3 { color: var(--paper); margin-top: 6px; }

/* ---------- Markdown study content ---------- */
.study-content {
  background: var(--card-bg);
  border: 1px solid var(--paper-line);
  border-radius: var(--radius-lg);
  padding: 32px clamp(20px, 4vw, 48px);
  max-width: 760px;
  box-shadow: var(--shadow-card);
}
.study-content h2 { border-bottom: 1px solid var(--paper-line); padding-bottom: 8px; margin-top: 1.6em; }
.study-content table { border-collapse: collapse; width: 100%; margin: 1em 0; font-size: 0.92rem; }
.study-content th, .study-content td { border: 1px solid var(--paper-line); padding: 8px 10px; text-align: left; }
.study-content th { background: var(--paper); font-family: var(--font-mono); font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.04em; }
.study-content blockquote {
  margin: 1.2em 0;
  padding: 12px 16px;
  background: #FBF1DD;
  border-left: 4px solid var(--gold);
  border-radius: var(--radius);
}
.study-content code { font-family: var(--font-mono); background: var(--paper); padding: 1px 5px; border-radius: 3px; }

/* ---------- OMR-style quiz bubbles ---------- */
.question-card {
  background: var(--card-bg);
  border: 1px solid var(--paper-line);
  border-radius: var(--radius-lg);
  padding: 26px;
  max-width: 720px;
  box-shadow: var(--shadow-card);
}
.question-meta {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 10px;
}
.question-text { font-size: 1.08rem; margin-bottom: 18px; }

.omr-option {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 11px 8px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: background 0.15s var(--ease);
}
.omr-option:hover { background: var(--paper); }
.omr-bubble {
  flex: 0 0 auto;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 2px solid var(--ink);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink);
  background: var(--card-bg);
  transition: background 0.15s var(--ease), transform 0.15s var(--ease);
}
.omr-option input { position: absolute; opacity: 0; width: 0; height: 0; }
.omr-option input:checked + .omr-bubble {
  background: var(--ink);
  color: var(--paper);
  transform: scale(1.06);
}
.omr-option.is-correct .omr-bubble { background: var(--teal); border-color: var(--teal); color: #fff; }
.omr-option.is-incorrect .omr-bubble { background: var(--red); border-color: var(--red); color: #fff; }
.omr-option-label { font-size: 0.99rem; }

.explanation-box {
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: var(--radius);
  background: var(--paper);
  border-left: 4px solid var(--teal);
  font-size: 0.92rem;
  display: none;
}
.explanation-box.is-visible { display: block; animation: fade-in 0.25s var(--ease); }

@keyframes fade-in {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ---------- Flashcards ---------- */
.flashcard { perspective: 1000px; height: 180px; cursor: pointer; }
.flashcard-inner {
  position: relative;
  width: 100%; height: 100%;
  transition: transform 0.5s var(--ease);
  transform-style: preserve-3d;
}
.flashcard.is-flipped .flashcard-inner { transform: rotateY(180deg); }
.flashcard-face {
  position: absolute; inset: 0;
  backface-visibility: hidden;
  border-radius: var(--radius-lg);
  border: 1px solid var(--paper-line);
  display: flex; align-items: center; justify-content: center;
  padding: 18px; text-align: center;
  background: var(--card-bg);
  box-shadow: var(--shadow-card);
  font-size: 0.98rem;
}
.flashcard-back { transform: rotateY(180deg); background: var(--ink); color: var(--paper); }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 2px solid var(--ink);
  background: #F3EEE0;
  padding: 40px 0 20px;
  font-size: 0.88rem;
  color: var(--ink-soft);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr repeat(3, 1fr);
  gap: 28px;
  padding-bottom: 24px;
}
.footer-brand .brand-mini { font-family: var(--font-display); font-size: 1.15rem; color: var(--ink); font-weight: 700; }
.footer-col h4 {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink);
  margin-bottom: 10px;
}
.footer-col ul { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 8px; }
.footer-col a { color: var(--ink-soft); text-decoration: none; }
.footer-col a:hover { color: var(--ink); text-decoration: underline; }
.footer-meta {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  border-top: 1px solid var(--paper-line);
  padding-top: 14px;
}

/* ---------- Utility ---------- */
.badge-row { display: flex; gap: 8px; flex-wrap: wrap; margin: 10px 0 20px; }
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 720px) {
  .nav-toggle { display: inline-block; }
  .main-nav {
    display: none;
    width: 100%;
    order: 3;
    justify-content: flex-start;
    padding-top: 10px;
    border-top: 1px solid var(--paper-line);
    margin-top: 10px;
  }
  .main-nav.is-open { display: flex; }
  .site-header .container { flex-wrap: wrap; }
  .hero { padding: 40px 0 30px; }
  .footer-grid { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}