/* ── QinYu — Academic identification key ── */

:root {
  --ink:         #1f2419;
  --ink-soft:    #3d4536;
  --forest:      #2d4a32;
  --forest-deep: #1e3422;
  --moss:        #6b8260;
  --paper:       #f7f3ea;
  --paper-warm:  #f1ead8;
  --rule:        #c9bfa6;
  --accent:      #8a3a2a;

  --radius:      4px;
  --transition:  0.15s ease;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: 'Lora', 'Noto Serif SC', 'Songti SC', Georgia, serif;
  background: var(--paper);
  background-image:
    radial-gradient(ellipse 800px 600px at 10% 0%, rgba(107,130,96,0.06), transparent 70%),
    radial-gradient(ellipse 600px 800px at 95% 100%, rgba(138,58,42,0.04), transparent 60%);
  color: var(--ink);
  min-height: 100vh;
  line-height: 1.75;
}

/* ── Layout ── */

.app {
  max-width: 680px;
  margin: 0 auto;
  padding: 0 20px 100px;
}

/* ── Header ── */

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px 0 18px;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 2px;
}

.logo {
  font-family: 'Cormorant Garamond', serif;
  font-size: 1.35rem;
  font-weight: 500;
  color: var(--forest-deep);
  letter-spacing: 0.04em;
}

.logo span {
  color: var(--moss);
}

.lang-btn {
  background: none;
  border: 1px solid var(--rule);
  border-radius: 2px;
  padding: 4px 14px;
  font-size: 0.8rem;
  font-family: 'Noto Serif SC', serif;
  color: var(--moss);
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 0.05em;
}

.lang-btn:hover {
  border-color: var(--moss);
  color: var(--forest);
}

/* ── Section transitions ── */

.section {
  display: none;
  animation: fadeIn 0.2s ease;
}

.section.active { display: block; }

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

/* ── Landing ── */

.landing-hero {
  padding: 52px 0 36px;
  text-align: center;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 32px;
}

.landing-eyebrow {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.85rem;
  letter-spacing: 0.18em;
  color: var(--moss);
  text-transform: uppercase;
  margin-bottom: 14px;
}

.landing-hero h1 {
  font-family: 'Cormorant Garamond', serif;
  font-size: 2.6rem;
  font-weight: 500;
  color: var(--forest-deep);
  letter-spacing: 0.02em;
  margin-bottom: 10px;
  line-height: 1.2;
}

.landing-hero p {
  font-family: 'Lora', serif;
  font-style: italic;
  color: var(--ink-soft);
  font-size: 0.95rem;
  max-width: 400px;
  margin: 0 auto;
}

/* ── Key card (landing) ── */

.key-list { display: flex; flex-direction: column; gap: 10px; }

.key-card {
  background: rgba(255,255,255,0.55);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--moss);
  padding: 20px 24px;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  display: flex;
  align-items: center;
  gap: 18px;
  width: 100%;
}

.key-card:hover {
  border-color: var(--moss);
  border-left-color: var(--forest);
  background: rgba(255,255,255,0.8);
}

.key-card-body { flex: 1; }

.key-card-title {
  font-family: 'Noto Serif SC', serif;
  font-size: 1rem;
  font-weight: 500;
  color: var(--forest-deep);
  margin-bottom: 3px;
  letter-spacing: 0.03em;
}

.key-card-sub {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.85rem;
  color: var(--moss);
  letter-spacing: 0.03em;
}

.key-card-arrow {
  color: var(--moss);
  font-size: 1rem;
  flex-shrink: 0;
  font-family: 'Cormorant Garamond', serif;
}

.coming-soon {
  text-align: center;
  color: var(--rule);
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.82rem;
  margin-top: 28px;
  letter-spacing: 0.08em;
}

/* ── Back button ── */

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: none;
  color: var(--moss);
  font-family: 'Cormorant Garamond', serif;
  font-size: 0.9rem;
  cursor: pointer;
  padding: 8px 0;
  margin-bottom: 8px;
  transition: var(--transition);
  letter-spacing: 0.04em;
}

.back-btn:hover { color: var(--forest); }

/* ── Group selector ── */

.section-title {
  font-family: 'Cormorant Garamond', serif;
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--forest-deep);
  margin: 12px 0 22px;
  letter-spacing: 0.02em;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 10px;
}

.group-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.group-card {
  background: rgba(255,255,255,0.5);
  border: 1px solid var(--rule);
  padding: 16px 14px 14px;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.group-card:hover {
  border-color: var(--moss);
  background: rgba(255,255,255,0.8);
}

.group-taxon {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.75rem;
  color: var(--moss);
  letter-spacing: 0.05em;
}

.group-name {
  font-family: 'Noto Serif SC', serif;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--forest-deep);
  line-height: 1.4;
}

/* ── Key header ── */

.key-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 4px;
}

.step-counter {
  font-family: 'Cormorant Garamond', serif;
  font-size: 0.8rem;
  color: var(--moss);
  letter-spacing: 0.08em;
  border: 1px solid var(--rule);
  padding: 3px 12px;
  border-radius: 1px;
}

/* ── Question card ── */

.question-card {
  background: rgba(255,255,255,0.6);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--moss);
  padding: 26px 24px;
  margin-bottom: 10px;
}

.step-label {
  font-family: 'Cormorant Garamond', serif;
  font-size: 0.72rem;
  font-style: italic;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--moss);
  margin-bottom: 12px;
}

.question-text {
  font-family: 'Lora', 'Noto Serif SC', serif;
  font-size: 1.05rem;
  font-weight: 400;
  color: var(--ink);
  line-height: 1.65;
  margin-bottom: 6px;
}

.display-text {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.9rem;
  color: var(--ink-soft);
  margin-bottom: 18px;
  padding: 8px 12px;
  background: var(--paper-warm);
  border-left: 2px solid var(--rule);
}

/* ── Figure illustration ── */

.node-figure {
  margin: 14px 0 6px;
  text-align: center;
}

.node-figure img {
  max-width: 100%;
  max-height: 240px;
  object-fit: contain;
  border: 1px solid var(--rule);
  background: var(--paper-warm);
}

.node-figure figcaption {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.75rem;
  color: var(--moss);
  margin-top: 5px;
  letter-spacing: 0.02em;
  line-height: 1.4;
}

.answer-buttons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-top: 20px;
}

.btn-yes, .btn-no {
  padding: 12px 10px;
  border-radius: var(--radius);
  font-size: 0.92rem;
  font-family: 'Lora', 'Noto Serif SC', serif;
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 0.04em;
  border: 1px solid;
}

.btn-yes {
  background: var(--forest);
  color: var(--paper);
  border-color: var(--forest-deep);
}

.btn-yes:hover {
  background: var(--forest-deep);
}

.btn-no {
  background: var(--paper-warm);
  color: var(--accent);
  border-color: var(--rule);
}

.btn-no:hover {
  background: var(--accent);
  color: var(--paper);
  border-color: var(--accent);
}

/* ── Result card ── */

.result-card {
  background: rgba(255,255,255,0.7);
  border: 1px solid var(--moss);
  border-left: 4px solid var(--forest);
  padding: 28px 26px;
  margin-bottom: 10px;
}

.result-label {
  font-family: 'Cormorant Garamond', serif;
  font-size: 0.72rem;
  font-style: italic;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--forest);
  margin-bottom: 12px;
}

.taxon-name {
  font-family: 'Cormorant Garamond', serif;
  font-size: 1.8rem;
  font-weight: 500;
  font-style: italic;
  color: var(--forest-deep);
  margin-bottom: 2px;
  line-height: 1.2;
}

.taxon-rank {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.8rem;
  color: var(--moss);
  letter-spacing: 0.08em;
  margin-bottom: 18px;
}

.result-figure {
  margin: 16px 0;
  text-align: center;
}

.result-figure img {
  max-width: 100%;
  max-height: 280px;
  object-fit: contain;
  border: 1px solid var(--rule);
  background: var(--paper-warm);
}

.result-figure figcaption {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.75rem;
  color: var(--moss);
  margin-top: 6px;
  line-height: 1.4;
}

.diagnostic-traits {
  border-top: 1px solid var(--rule);
  padding-top: 14px;
  margin-top: 6px;
}

.diagnostic-traits strong {
  display: block;
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--moss);
  margin-bottom: 10px;
  font-weight: 400;
}

.diagnostic-traits ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.diagnostic-traits li {
  font-size: 0.88rem;
  color: var(--ink);
  padding: 5px 10px;
  background: var(--paper-warm);
  display: flex;
  gap: 8px;
  line-height: 1.5;
}

.diagnostic-traits li::before {
  content: "—";
  color: var(--moss);
  font-family: 'Cormorant Garamond', serif;
  flex-shrink: 0;
}

.result-actions { margin-top: 20px; }

.btn-restart {
  background: none;
  border: 1px solid var(--rule);
  padding: 9px 18px;
  font-size: 0.85rem;
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  color: var(--moss);
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 0.06em;
  width: 100%;
}

.btn-restart:hover {
  border-color: var(--forest);
  color: var(--forest);
}

/* ── Group result (intermediate) ── */

.group-result-card {
  background: rgba(255,255,255,0.55);
  border: 1px dashed var(--moss);
  padding: 24px;
  margin-bottom: 10px;
}

.group-result-name {
  font-family: 'Cormorant Garamond', serif;
  font-size: 1.5rem;
  font-weight: 500;
  font-style: italic;
  color: var(--forest-deep);
  margin-bottom: 4px;
}

.group-result-included {
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.85rem;
  color: var(--moss);
  margin: 10px 0;
  line-height: 1.6;
}

/* ── History ── */

.history {
  margin-top: 10px;
}

.history details {
  background: rgba(255,255,255,0.4);
  border: 1px solid var(--rule);
  overflow: hidden;
}

.history summary {
  padding: 9px 14px;
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  color: var(--moss);
  cursor: pointer;
  user-select: none;
  list-style: none;
}

.history summary::-webkit-details-marker { display: none; }
.history summary::before { content: "▶ "; font-size: 0.6rem; }
details[open] summary::before { content: "▼ "; }

.history-list {
  border-top: 1px solid var(--rule);
  padding: 10px 14px;
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.history-item {
  font-size: 0.8rem;
  color: var(--ink-soft);
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 10px;
  font-family: 'Lora', 'Noto Serif SC', serif;
}

.history-q { flex: 1; line-height: 1.45; }

.history-a {
  font-family: 'Cormorant Garamond', serif;
  font-weight: 500;
  font-size: 0.75rem;
  padding: 1px 8px;
  flex-shrink: 0;
}

.history-a.yes { color: var(--forest); border: 1px solid var(--moss); }
.history-a.no  { color: var(--accent); border: 1px solid var(--rule); }

/* ── Citation ── */

.citation {
  margin-top: 40px;
  padding: 14px 0;
  border-top: 1px solid var(--rule);
  font-family: 'Cormorant Garamond', serif;
  font-style: italic;
  font-size: 0.78rem;
  color: var(--moss);
  line-height: 1.65;
  letter-spacing: 0.02em;
}

/* ── Responsive ── */

@media (max-width: 480px) {
  .landing-hero h1 { font-size: 2rem; }
  .group-grid { grid-template-columns: 1fr 1fr; gap: 7px; }
  .group-card { padding: 13px 10px; }
  .group-name { font-size: 0.82rem; }
  .answer-buttons { grid-template-columns: 1fr 1fr; }
  .question-text { font-size: 0.97rem; }
  .taxon-name { font-size: 1.5rem; }
}