:root {
  --paper: #fbf7ee;
  --paper-strong: #f1e8d6;
  --ink: #22201b;
  --muted: #6a6458;
  --border: #d7c9ae;
  --accent: #9b5c2d;
  --accent-dark: #5f3318;
  --card: #fffdf8;
  --shadow: 0 16px 40px rgba(73, 46, 24, 0.08);
  --max-width: 1100px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(155, 92, 45, 0.11), transparent 28%),
    radial-gradient(circle at top right, rgba(95, 51, 24, 0.10), transparent 24%),
    linear-gradient(180deg, #f5efe2 0%, #fbf7ee 16%, #f9f2e3 100%);
  font-family: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Georgia, serif;
  line-height: 1.6;
}

a {
  color: var(--accent-dark);
}

a:hover {
  color: var(--accent);
}

code {
  font-family: "SFMono-Regular", Menlo, Consolas, "Liberation Mono", monospace;
  font-size: 0.95em;
  background: rgba(95, 51, 24, 0.06);
  padding: 0.12rem 0.34rem;
  border-radius: 0.3rem;
}

.page {
  width: min(var(--max-width), calc(100vw - 2rem));
  margin: 0 auto;
  padding: 1.25rem 0 4rem;
}

.hero {
  margin-top: 1rem;
  background: linear-gradient(135deg, rgba(155, 92, 45, 0.14), rgba(255, 255, 255, 0.78));
  border: 1px solid rgba(95, 51, 24, 0.12);
  border-radius: 1.5rem;
  padding: 1.6rem 1.6rem 1.3rem;
  box-shadow: var(--shadow);
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-dark);
  font-size: 0.82rem;
  margin: 0 0 0.3rem;
}

h1 {
  margin: 0;
  line-height: 1.12;
  font-size: clamp(2rem, 4vw, 3.3rem);
}

.subtitle {
  color: var(--muted);
  max-width: 70ch;
  margin-top: 0.9rem;
  font-size: 1.02rem;
}

.top-nav,
.chapter-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1rem;
}

.nav-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  text-decoration: none;
  border-radius: 999px;
  padding: 0.55rem 0.9rem;
  background: rgba(255, 255, 255, 0.76);
  border: 1px solid rgba(95, 51, 24, 0.12);
  color: var(--accent-dark);
  font-size: 0.95rem;
}

.nav-pill.active {
  background: rgba(155, 92, 45, 0.18);
  font-weight: 700;
}

.grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  margin-top: 1.2rem;
}

.card,
.panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 1.25rem;
  box-shadow: var(--shadow);
  padding: 1.2rem 1.2rem 1rem;
}

.card h3,
.panel h2 {
  margin-top: 0;
  line-height: 1.18;
}

.card p,
.panel p,
.panel li {
  max-width: 74ch;
}

.sections {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.formula {
  margin: 0.8rem 0;
  padding: 0.8rem 0.95rem;
  border-left: 4px solid var(--accent);
  background: linear-gradient(90deg, rgba(155, 92, 45, 0.09), rgba(255, 255, 255, 0.96));
  border-radius: 0.8rem;
  overflow-x: auto;
}

.formula mjx-container {
  margin: 0 !important;
  font-size: 1.1rem !important;
}

.source-note {
  margin-top: 0.9rem;
  padding: 0.8rem 0.95rem;
  background: rgba(241, 232, 214, 0.75);
  border-radius: 0.9rem;
  border: 1px solid var(--border);
  color: var(--accent-dark);
  font-size: 0.95rem;
}

.source-list,
.toc,
.must-know-list {
  padding-left: 1.2rem;
}

.chapter-links {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  margin-top: 1.1rem;
}

.chapter-link {
  text-decoration: none;
  color: inherit;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 1.2rem;
  padding: 1rem;
  box-shadow: var(--shadow);
  transition: transform 0.16s ease, border-color 0.16s ease;
}

.chapter-link:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
}

.chapter-number {
  color: var(--accent-dark);
  font-size: 0.84rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.tool-links,
.recap-toc {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1rem;
}

.tool-link {
  text-decoration: none;
  color: inherit;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 1.2rem;
  padding: 1rem;
  box-shadow: var(--shadow);
  min-width: min(100%, 290px);
  flex: 1 1 290px;
}

.recap-entry {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 1.2rem;
  box-shadow: var(--shadow);
  padding: 1.1rem 1.15rem 1rem;
}

.entry-head,
.question-top {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  align-items: flex-start;
  flex-wrap: wrap;
}

.question-number {
  color: var(--accent-dark);
  font-size: 0.84rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 0 0 0.35rem;
}

.badge-row,
.question-tags,
.chapter-ref-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.6rem;
}

.badge,
.tag,
.status-chip {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  padding: 0.18rem 0.6rem;
  font-size: 0.83rem;
  border: 1px solid rgba(95, 51, 24, 0.15);
  background: rgba(95, 51, 24, 0.07);
  color: var(--accent-dark);
}

.badge.lecture-backed {
  background: rgba(86, 124, 73, 0.14);
  color: #355127;
  border-color: rgba(53, 81, 39, 0.18);
}

.badge.mixed {
  background: rgba(155, 92, 45, 0.12);
}

.badge.correction-only,
.badge.terse-correction {
  background: rgba(168, 62, 35, 0.12);
  color: #7a2712;
  border-color: rgba(122, 39, 18, 0.2);
}

.warning-box,
.reveal-box {
  margin-top: 0.9rem;
  padding: 0.85rem 0.95rem;
  border-radius: 0.95rem;
  border: 1px solid var(--border);
  background: rgba(241, 232, 214, 0.58);
}

.warning-box {
  border-color: rgba(122, 39, 18, 0.22);
  background: rgba(168, 62, 35, 0.08);
}

.meta-list,
.answer-checklist,
.chapter-ref-list {
  padding-left: 1.2rem;
  margin: 0.65rem 0 0;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 0.9rem;
  font-size: 0.95rem;
  background: rgba(255, 255, 255, 0.75);
  border-radius: 0.85rem;
  overflow: hidden;
}

.comparison-table th,
.comparison-table td {
  text-align: left;
  padding: 0.7rem 0.75rem;
  border-bottom: 1px solid rgba(95, 51, 24, 0.1);
  vertical-align: top;
}

.comparison-table th {
  background: rgba(155, 92, 45, 0.08);
  color: var(--accent-dark);
  font-weight: 700;
}

.quiz-toolbar {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  margin-top: 1rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.field label {
  font-weight: 700;
  color: var(--accent-dark);
  font-size: 0.92rem;
}

.field select,
.field input,
.text-answer,
.fill-answer {
  width: 100%;
  border: 1px solid rgba(95, 51, 24, 0.18);
  border-radius: 0.9rem;
  background: rgba(255, 255, 255, 0.88);
  color: var(--ink);
  font: inherit;
  padding: 0.65rem 0.8rem;
}

.text-answer {
  min-height: 8rem;
  resize: vertical;
}

.quiz-actions,
.question-actions,
.mark-group {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
  margin-top: 0.85rem;
}

.button {
  cursor: pointer;
  border: 1px solid rgba(95, 51, 24, 0.15);
  border-radius: 999px;
  padding: 0.56rem 0.9rem;
  background: rgba(255, 255, 255, 0.9);
  color: var(--accent-dark);
  font: inherit;
}

.button.primary {
  background: rgba(155, 92, 45, 0.14);
  font-weight: 700;
}

.stats-grid {
  display: grid;
  gap: 0.8rem;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  margin-top: 1rem;
}

.stat-card {
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid rgba(95, 51, 24, 0.12);
  border-radius: 1rem;
  padding: 0.85rem 0.95rem;
}

.stat-card strong {
  display: block;
  font-size: 1.25rem;
  line-height: 1.1;
  color: var(--accent-dark);
}

.question-list {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.quiz-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 1.2rem;
  box-shadow: var(--shadow);
  padding: 1.05rem 1.1rem 1rem;
}

.quiz-card.correct {
  border-color: rgba(53, 81, 39, 0.35);
}

.quiz-card.partial {
  border-color: rgba(155, 92, 45, 0.35);
}

.quiz-card.missed {
  border-color: rgba(122, 39, 18, 0.3);
}

.question-meta {
  color: var(--muted);
  font-size: 0.92rem;
  margin-top: 0.35rem;
}

.choice-list {
  display: grid;
  gap: 0.65rem;
  margin-top: 0.8rem;
}

.choice-row {
  display: flex;
  gap: 0.6rem;
  align-items: flex-start;
  padding: 0.65rem 0.7rem;
  border-radius: 0.9rem;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid rgba(95, 51, 24, 0.08);
}

.status-line {
  margin-top: 0.75rem;
  color: var(--accent-dark);
  font-size: 0.92rem;
  font-weight: 700;
}

.small-note {
  color: var(--muted);
  font-size: 0.92rem;
}

footer {
  color: var(--muted);
  font-size: 0.92rem;
  margin-top: 1.2rem;
  padding-top: 0.3rem;
}

@media (max-width: 720px) {
  .page {
    width: min(var(--max-width), calc(100vw - 1rem));
  }

  .hero,
  .panel,
  .card,
  .chapter-link {
    border-radius: 1rem;
  }
}