@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+TC:wght@300;400;500;700;900&family=Inter:wght@300;400;600;700&display=swap');

:root {
  --bg-deep: #050a1a;
  --bg-mid: #0a1628;
  --accent-blue: #00d4ff;
  --accent-purple: #7c3aed;
  --accent-cyan: #06b6d4;
  --accent-pink: #f472b6;
  --accent-green: #10b981;
  --glass-bg: rgba(255,255,255,0.04);
  --glass-border: rgba(255,255,255,0.10);
  --glass-hover: rgba(255,255,255,0.08);
  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-accent: #00d4ff;
  --sidebar-width: 260px;
  --sidebar-collapsed-width: 72px;
  --radius: 16px;
  --shadow: 0 8px 32px rgba(0,0,0,0.4);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Noto Sans TC', 'Inter', sans-serif;
  background: var(--bg-deep);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
}

/* ── Animated Background ── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 10%, rgba(0,100,255,0.12) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 80%, rgba(124,58,237,0.15) 0%, transparent 55%),
    radial-gradient(ellipse 50% 40% at 60% 30%, rgba(0,212,255,0.08) 0%, transparent 50%);
  z-index: -1;
  animation: bgPulse 12s ease-in-out infinite alternate;
}

@keyframes bgPulse {
  0%   { opacity: 0.7; }
  100% { opacity: 1; }
}

/* ── Stars ── */
.stars {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
}
.stars::before, .stars::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(1px 1px at 10% 15%, rgba(255,255,255,0.6) 0%, transparent 100%),
    radial-gradient(1px 1px at 30% 40%, rgba(255,255,255,0.4) 0%, transparent 100%),
    radial-gradient(1px 1px at 55% 20%, rgba(255,255,255,0.5) 0%, transparent 100%),
    radial-gradient(1px 1px at 75% 60%, rgba(255,255,255,0.3) 0%, transparent 100%),
    radial-gradient(1px 1px at 90% 85%, rgba(255,255,255,0.6) 0%, transparent 100%),
    radial-gradient(1px 1px at 45% 75%, rgba(255,255,255,0.4) 0%, transparent 100%),
    radial-gradient(1px 1px at 20% 90%, rgba(255,255,255,0.5) 0%, transparent 100%),
    radial-gradient(1px 1px at 65% 50%, rgba(255,255,255,0.3) 0%, transparent 100%);
  animation: twinkle 6s ease-in-out infinite alternate;
}
.stars::after { animation-delay: 3s; opacity: 0.5; }

@keyframes twinkle {
  0%   { opacity: 0.4; }
  100% { opacity: 1; }
}

/* ── Layout ── */
.layout { display: flex; min-height: 100vh; }

/* ── Sidebar ── */
.sidebar {
  position: fixed;
  top: 0; left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: rgba(5,10,26,0.85);
  backdrop-filter: blur(20px);
  border-right: 1px solid var(--glass-border);
  display: flex;
  flex-direction: column;
  z-index: 100;
  overflow-y: auto;
  overflow-x: hidden;
  transition: width 0.3s ease;
}

body.sidebar-collapsed .sidebar {
  width: var(--sidebar-collapsed-width);
}

.logo-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.collapse-btn {
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.1);
  color: var(--text-secondary);
  border-radius: 6px;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s;
}
.collapse-btn:hover {
  background: rgba(255,255,255,0.15);
  color: var(--text-primary);
}
body.sidebar-collapsed .collapse-btn {
  transform: rotate(180deg);
  margin: 0 auto;
}

.sidebar-logo {
  padding: 28px 20px 16px;
  border-bottom: 1px solid var(--glass-border);
}
.sidebar-logo .logo-icon {
  font-size: 2rem;
  display: block;
  margin-bottom: 8px;
}
.sidebar-logo h2 {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-blue);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  line-height: 1.4;
  transition: opacity 0.2s, height 0.2s;
}
.sidebar-logo p {
  font-size: 0.72rem;
  color: var(--text-secondary);
  margin-top: 4px;
  transition: opacity 0.2s, height 0.2s;
}

body.sidebar-collapsed .sidebar-title,
body.sidebar-collapsed .sidebar-subtitle {
  opacity: 0;
  height: 0;
  margin: 0;
  overflow: hidden;
}
body.sidebar-collapsed .progress-bar-container {
  display: none;
}

.progress-bar-container {
  padding: 12px 20px;
  border-bottom: 1px solid var(--glass-border);
}
.progress-label { font-size: 0.7rem; color: var(--text-secondary); margin-bottom: 6px; }
.progress-bar {
  height: 4px;
  background: rgba(255,255,255,0.1);
  border-radius: 99px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-blue), var(--accent-purple));
  border-radius: 99px;
  width: 0%;
  transition: width 0.3s ease;
}

.nav-list { padding: 12px 0; flex: 1; }

.nav-item { position: relative; }

.nav-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 20px;
  font-size: 0.82rem;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all 0.25s ease;
  border-left: 3px solid transparent;
}
.nav-link:hover {
  color: var(--text-primary);
  background: var(--glass-hover);
  border-left-color: var(--accent-blue);
}
.nav-link.active {
  color: var(--accent-blue);
  background: rgba(0,212,255,0.08);
  border-left-color: var(--accent-blue);
  font-weight: 500;
}
body.sidebar-collapsed .nav-text {
  display: none;
}
body.sidebar-collapsed .nav-link {
  justify-content: center;
  padding: 12px 0;
}
body.sidebar-collapsed .nav-number {
  display: none;
}
.nav-icon { font-size: 1.2rem; flex-shrink: 0; }
.nav-number {
  font-size: 0.65rem;
  color: var(--accent-purple);
  font-weight: 700;
  min-width: 20px;
}

/* ── Main Content ── */
.main-content {
  margin-left: var(--sidebar-width);
  flex: 1;
  padding: 0 32px 60px;
  max-width: calc(100vw - var(--sidebar-width));
  transition: margin-left 0.3s ease, max-width 0.3s ease;
}

body.sidebar-collapsed .main-content {
  margin-left: var(--sidebar-collapsed-width);
  max-width: calc(100vw - var(--sidebar-collapsed-width));
}

/* ── Hero Header ── */
.hero {
  text-align: center;
  padding: 80px 20px 60px;
  position: relative;
}
.hero-badge {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(0,212,255,0.12);
  border: 1px solid rgba(0,212,255,0.3);
  border-radius: 99px;
  font-size: 0.78rem;
  color: var(--accent-blue);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 20px;
  animation: fadeInDown 0.8s ease both;
}
.hero h1 {
  font-size: clamp(2rem, 4vw, 3.2rem);
  font-weight: 900;
  line-height: 1.2;
  background: linear-gradient(135deg, #ffffff 0%, var(--accent-blue) 50%, var(--accent-purple) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 16px;
  animation: fadeInDown 0.8s ease 0.1s both;
}
.hero-subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  animation: fadeInDown 0.8s ease 0.2s both;
}
.hero-meta {
  display: flex;
  gap: 24px;
  justify-content: center;
  margin-top: 28px;
  flex-wrap: wrap;
  animation: fadeInDown 0.8s ease 0.3s both;
}
.hero-meta-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 99px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}
.hero-meta-item span:first-child { font-size: 1rem; }

/* ── Section Cards ── */
.chapter-section {
  margin-bottom: 64px;
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.7s ease;
}
.chapter-section.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Section Layout ── */
.section-layout {
  display: grid;
  grid-template-columns: 1fr 420px;
  gap: 28px;
  align-items: start;
}
.section-layout.single-col {
  grid-template-columns: 1fr;
}
.section-media {
  position: sticky;
  top: 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 28px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--glass-border);
}
.section-number {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  border-radius: 14px;
  font-size: 1.1rem;
  font-weight: 800;
  flex-shrink: 0;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
  color: white;
}
.section-title { flex: 1; }
.section-title h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}
.section-title p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-top: 3px;
}

/* ── Glass Card ── */
.glass-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  padding: 24px 28px;
  backdrop-filter: blur(12px);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}
.glass-card:hover {
  border-color: rgba(0,212,255,0.25);
  box-shadow: 0 0 30px rgba(0,212,255,0.06);
}

/* ── Content Grid ── */
.content-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 20px;
}
.content-grid.single { grid-template-columns: 1fr; }
.content-grid.triple { grid-template-columns: 1fr 1fr 1fr; }

/* ── Summary Box ── */
.summary-box {
  line-height: 1.85;
  font-size: 0.92rem;
  color: var(--text-primary);
}
.summary-box p { margin-bottom: 14px; }
.summary-box h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--accent-blue);
  margin: 18px 0 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.summary-box h3::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 16px;
  background: var(--accent-blue);
  border-radius: 2px;
}
.summary-box ul { padding-left: 20px; }
.summary-box li {
  margin-bottom: 8px;
  color: var(--text-secondary);
}
.summary-box strong { color: var(--accent-cyan); }

/* ── Key Terms ── */
.key-terms-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 14px;
  margin-top: 16px;
}
.key-terms-grid.single-col-grid {
  grid-template-columns: 1fr;
}
.term-card {
  background: rgba(0,212,255,0.05);
  border: 1px solid rgba(0,212,255,0.15);
  border-radius: 12px;
  padding: 14px 16px;
  cursor: pointer;
  transition: all 0.3s ease;
  perspective: 600px;
}
.term-card:hover {
  background: rgba(0,212,255,0.1);
  border-color: rgba(0,212,255,0.35);
  transform: translateY(-2px);
}
.term-card .term-front { }
.term-card .term-en {
  font-size: 0.72rem;
  color: var(--accent-blue);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.term-card .term-zh {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 4px 0;
}
.term-card .term-def {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.5;
  display: none;
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--glass-border);
}
.term-card.expanded .term-def { display: block; }

/* ── Image Gallery ── */
.image-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 16px;
}
.image-gallery.single-col-gallery {
  grid-template-columns: 1fr;
}
.img-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  overflow: hidden;
  transition: all 0.3s ease;
}
.img-card:hover {
  border-color: rgba(0,212,255,0.3);
  transform: translateY(-3px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.3);
}
.img-card img {
  width: 100%;
  height: 200px;
  object-fit: contain;
  background: rgba(0,0,0,0.3);
  padding: 8px;
  display: block;
}
.img-caption {
  padding: 12px 16px;
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.5;
  border-top: 1px solid var(--glass-border);
}

/* ── Canvas Animation ── */
.animation-section {
  margin-top: 20px;
}
.animation-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}
.animation-header h3 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
}
.anim-btn {
  padding: 6px 16px;
  background: rgba(0,212,255,0.12);
  border: 1px solid rgba(0,212,255,0.3);
  border-radius: 99px;
  color: var(--accent-blue);
  font-size: 0.78rem;
  cursor: pointer;
  transition: all 0.2s ease;
}
.anim-btn:hover {
  background: rgba(0,212,255,0.22);
}
.canvas-container {
  background: rgba(0,0,0,0.4);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  overflow: hidden;
}
canvas {
  display: block;
  width: 100%;
  height: auto;
}

/* ── Formula Box ── */
.formula-box {
  background: rgba(124,58,237,0.08);
  border: 1px solid rgba(124,58,237,0.2);
  border-radius: 12px;
  padding: 18px 22px;
  margin: 16px 0;
  text-align: center;
}
.formula-box .formula-label {
  font-size: 0.75rem;
  color: var(--accent-purple);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 10px;
}

/* ── Info Cards ── */
.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 14px;
  margin-top: 16px;
}
.info-grid.single-col-grid {
  grid-template-columns: 1fr;
}
.info-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 16px;
  text-align: center;
  transition: all 0.3s ease;
}
.info-card:hover {
  background: var(--glass-hover);
  transform: translateY(-2px);
}
.info-card .info-icon { font-size: 2rem; margin-bottom: 8px; }
.info-card .info-title {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}
.info-card .info-desc {
  font-size: 0.75rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ── Earth Layers Visual ── */
.earth-visual {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

/* ── Quiz Section ── */
.quiz-section { }
.quiz-section > .glass-card > p {
  margin-bottom: 20px;
  color: var(--text-secondary);
}
.quiz-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}
.flip-card {
  height: 180px;
  perspective: 1000px;
  cursor: pointer;
}
.flip-card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4,0,0.2,1);
}
.flip-card.flipped .flip-card-inner { transform: rotateY(180deg); }
.flip-card-front, .flip-card-back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  border-radius: var(--radius);
  padding: 22px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.flip-card-front {
  background: rgba(0,212,255,0.06);
  border: 1px solid rgba(0,212,255,0.2);
}
.flip-card-back {
  background: rgba(124,58,237,0.1);
  border: 1px solid rgba(124,58,237,0.3);
  transform: rotateY(180deg);
}
.flip-card-front .q-label {
  font-size: 0.7rem;
  color: var(--accent-blue);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 10px;
}
.flip-card-front h3 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.5;
}
.flip-card-back .a-label {
  font-size: 0.7rem;
  color: var(--accent-purple);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 10px;
}
.flip-card-back p {
  font-size: 0.88rem;
  color: var(--text-primary);
  line-height: 1.6;
}
.flip-hint {
  font-size: 0.7rem;
  color: var(--text-secondary);
  margin-top: auto;
  text-align: right;
  padding-top: 8px;
}

/* ── Phase Names Table ── */
.phase-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  margin-top: 12px;
}
.phase-table th {
  background: rgba(0,212,255,0.1);
  color: var(--accent-blue);
  padding: 10px 14px;
  text-align: left;
  font-weight: 600;
  border-bottom: 1px solid var(--glass-border);
}
.phase-table td {
  padding: 10px 14px;
  border-bottom: 1px solid rgba(255,255,255,0.04);
  color: var(--text-secondary);
}
.phase-table tr:hover td { background: var(--glass-hover); color: var(--text-primary); }
.phase-table .phase-code {
  font-family: 'Courier New', monospace;
  color: var(--accent-cyan);
  font-weight: 700;
  font-size: 0.95rem;
}

/* ── Depth Scale ── */
.depth-scale {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.depth-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 10px 14px;
  background: var(--glass-bg);
  border-radius: 10px;
  border-left: 3px solid var(--accent-blue);
  transition: all 0.2s;
}
.depth-item:hover { background: var(--glass-hover); }
.depth-km {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent-blue);
  min-width: 60px;
}
.depth-name {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
}
.depth-desc {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

/* ── Footer ── */
footer {
  text-align: center;
  padding: 40px 20px;
  border-top: 1px solid var(--glass-border);
  margin-top: 60px;
  color: var(--text-secondary);
  font-size: 0.82rem;
}
footer .footer-logo { font-size: 1.5rem; margin-bottom: 8px; }
footer a { color: var(--accent-blue); text-decoration: none; }

/* ── Animations ── */
@keyframes fadeInDown {
  from { opacity: 0; transform: translateY(-20px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes pulseGlow {
  0%, 100% { box-shadow: 0 0 20px rgba(0,212,255,0.2); }
  50%       { box-shadow: 0 0 40px rgba(0,212,255,0.5); }
}

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-deep); }
::-webkit-scrollbar-thumb {
  background: rgba(0,212,255,0.3);
  border-radius: 3px;
}

/* ── Section Tag ── */
.section-tag {
  display: inline-block;
  padding: 3px 10px;
  background: rgba(0,212,255,0.1);
  border: 1px solid rgba(0,212,255,0.2);
  border-radius: 99px;
  font-size: 0.7rem;
  color: var(--accent-blue);
  margin-bottom: 12px;
}

/* ── Callout Box ── */
.callout {
  border-radius: 12px;
  padding: 16px 20px;
  margin: 14px 0;
  display: flex;
  gap: 12px;
  align-items: flex-start;
}
.callout.info {
  background: rgba(0,212,255,0.06);
  border: 1px solid rgba(0,212,255,0.2);
}
.callout.warning {
  background: rgba(251,191,36,0.06);
  border: 1px solid rgba(251,191,36,0.2);
}
.callout.success {
  background: rgba(16,185,129,0.06);
  border: 1px solid rgba(16,185,129,0.2);
}
.callout-icon { font-size: 1.3rem; flex-shrink: 0; }
.callout-text { font-size: 0.87rem; line-height: 1.6; color: var(--text-secondary); }
.callout-text strong { color: var(--text-primary); }

/* ── Responsive ── */
@media (max-width: 900px) {
  .sidebar { transform: translateX(-100%); transition: transform 0.3s; }
  .sidebar.open { transform: translateX(0); }
  .main-content { margin-left: 0; max-width: 100vw; padding: 0 16px 60px; }
  .content-grid { grid-template-columns: 1fr; }
  .content-grid.triple { grid-template-columns: 1fr; }
  .menu-btn {
    display: flex;
    position: fixed;
    top: 16px; left: 16px;
    z-index: 200;
    width: 44px; height: 44px;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 10px;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-primary);
    font-size: 1.3rem;
  }
}
@media (min-width: 901px) {
  .menu-btn { display: none; }
}

/* ── Key Questions (Accordion) ── */
.key-questions {
  margin-top: 20px;
}
.key-questions-header {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--accent-cyan);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(6,182,212,0.25);
  display: flex;
  align-items: center;
  gap: 8px;
}
.kq-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.kq-card {
  background: rgba(6,182,212,0.04);
  border: 1px solid rgba(6,182,212,0.15);
  border-radius: 12px;
  overflow: hidden;
  cursor: pointer;
  transition: border-color 0.25s ease;
}
.kq-card:hover {
  border-color: rgba(6,182,212,0.35);
}
.kq-front {
  padding: 14px 18px;
  display: flex;
  align-items: flex-start;
  gap: 12px;
}
.kq-badge {
  flex-shrink: 0;
  font-size: 0.68rem;
  font-weight: 700;
  color: var(--accent-cyan);
  background: rgba(6,182,212,0.12);
  border: 1px solid rgba(6,182,212,0.25);
  border-radius: 6px;
  padding: 2px 7px;
  letter-spacing: 0.06em;
  margin-top: 2px;
}
.kq-question {
  flex: 1;
  font-size: 0.87rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.5;
}
.kq-hint {
  font-size: 0.72rem;
  color: var(--text-secondary);
  white-space: nowrap;
  margin-top: 3px;
  transition: opacity 0.2s;
}
.kq-back {
  display: none;
  padding: 0 18px 14px 42px;
  font-size: 0.84rem;
  color: var(--text-secondary);
  line-height: 1.7;
  border-top: 1px solid rgba(6,182,212,0.12);
  padding-top: 12px;
  margin-top: 0;
}
.kq-back strong { color: var(--text-primary); }
.kq-card.expanded { border-color: rgba(6,182,212,0.4); }
.kq-card.expanded .kq-back { display: block; }
.kq-card.expanded .kq-hint { opacity: 0; pointer-events: none; }

/* ── Animation Controls ── */
.anim-controls {
  display: flex;
  gap: 8px;
  align-items: center;
}
.anim-enlarge-btn {
  padding: 6px 14px;
  background: rgba(124,58,237,0.12);
  border: 1px solid rgba(124,58,237,0.3);
  border-radius: 99px;
  color: var(--accent-purple);
  font-size: 0.78rem;
  cursor: pointer;
  transition: all 0.2s ease;
}
.anim-enlarge-btn:hover { background: rgba(124,58,237,0.22); }

/* ── Lightbox ── */
.zoomable {
  cursor: zoom-in;
}
.lightbox {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(5, 10, 26, 0.9);
  backdrop-filter: blur(8px);
  align-items: center;
  justify-content: center;
  flex-direction: column;
  opacity: 0;
  transition: opacity 0.3s ease;
}
.lightbox.active {
  display: flex;
  opacity: 1;
}
.lightbox-close {
  position: absolute;
  top: 20px;
  right: 30px;
  color: #fff;
  font-size: 40px;
  font-weight: bold;
  cursor: pointer;
  transition: 0.3s;
}
.lightbox-close:hover {
  color: var(--accent-blue);
}
.lightbox-content {
  max-width: 90%;
  max-height: 80vh;
  border-radius: 8px;
  box-shadow: 0 0 40px rgba(0,0,0,0.6);
  transform: scale(0.95);
  transition: transform 0.3s ease;
}
.lightbox.active .lightbox-content {
  transform: scale(1);
}
.lightbox-caption {
  margin-top: 16px;
  color: var(--text-primary);
  font-size: 1rem;
  text-align: center;
  max-width: 80%;
}