/* ===================================================================
   YOGA VIDYA - Anatomy & Physiology Digital Textbook & Exam Portal
   Paper 490E1120: Annamalai & Anna University (M.Sc. Yoga)
   Modern Medical-Yogic Aesthetics, Glassmorphism, and Fluid Animations
   =================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=Merriweather:ital,wght@0,300;0,400;0,700;1,300;1,400&family=Fira+Code:wght@400;600&display=swap');

:root {
  /* Light Theme (Default Modern Medical / Clean Textbook) */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #f1f5f9;
  --border-color: #e2e8f0;
  --border-active: #2563eb;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --text-accent: #2563eb;
  --accent-gold: #d97706;
  --accent-emerald: #059669;
  --accent-rose: #e11d48;
  --accent-cyan: #0891b2;
  --accent-purple: #7c3aed;
  --font-sans: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --font-serif: 'Merriweather', Georgia, serif;
  --font-code: 'Fira Code', monospace;
  --card-radius: 14px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05), 0 1px 2px rgba(0, 0, 0, 0.03);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* Dark Theme (Night Study Mode) */
body.theme-dark {
  --bg-primary: #090d16;
  --bg-secondary: #111827;
  --bg-card: #141e33;
  --bg-card-hover: #1e293b;
  --border-color: #1f2937;
  --border-active: #60a5fa;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-accent: #60a5fa;
  --accent-gold: #fbbf24;
  --accent-emerald: #34d399;
  --accent-rose: #fb7185;
  --accent-cyan: #22d3ee;
  --accent-purple: #a78bfa;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 10px 20px -3px rgba(0, 0, 0, 0.6);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.7);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-main);
  line-height: 1.7;
  min-height: 100vh;
  transition: background-color 0.25s ease, color 0.25s ease;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* Custom Scrollbars */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary);
}
::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}
body.theme-dark ::-webkit-scrollbar-thumb {
  background: #374151;
}

/* ================= Header & Navbar ================= */
.app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(14px);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 1.75rem;
  box-shadow: var(--shadow-sm);
  transition: all 0.25s ease;
}
body.theme-dark .app-header {
  background: rgba(17, 24, 39, 0.92);
}

.header-inner {
  max-width: 1360px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.logo-area {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  text-decoration: none;
  color: inherit;
  cursor: pointer;
  flex-shrink: 0;
}

.logo-badge {
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, #1e3a8a, #0284c7);
  color: #ffffff;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 800;
  box-shadow: 0 4px 12px rgba(2, 132, 199, 0.3);
}

.logo-text h1 {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: linear-gradient(135deg, #1e3a8a, #0284c7);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.2;
}
body.theme-dark .logo-text h1 {
  background: linear-gradient(135deg, #60a5fa, #38bdf8);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.logo-text p {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
}

/* Desktop Nav Links */
.desktop-nav {
  display: flex;
  align-items: center;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  list-style: none;
}
.nav-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 0.55rem 0.9rem;
  border-radius: 9px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: 0.45rem;
}
.nav-btn:hover {
  background: var(--bg-card-hover);
  color: var(--text-main);
}
.nav-btn.active {
  background: rgba(37, 99, 235, 0.1);
  color: var(--text-accent);
  border-color: rgba(37, 99, 235, 0.25);
  font-weight: 700;
}
body.theme-dark .nav-btn.active {
  background: rgba(96, 165, 250, 0.15);
  border-color: rgba(96, 165, 250, 0.3);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.theme-toggle-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.48rem 0.85rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.45rem;
  transition: all 0.2s ease;
}
.theme-toggle-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--text-accent);
}

/* Mobile Bottom Nav */
.mobile-bottom-nav {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 0.4rem 0.5rem;
  z-index: 99;
  justify-content: space-around;
  backdrop-filter: blur(12px);
  box-shadow: 0 -4px 12px rgba(0, 0, 0, 0.05);
}
.mobile-nav-item {
  background: transparent;
  border: none;
  color: var(--text-muted);
  display: flex;
  flex-direction: column;
  align-items: center;
  font-size: 0.7rem;
  font-weight: 600;
  cursor: pointer;
  padding: 0.25rem 0.5rem;
  border-radius: 8px;
  transition: all 0.2s ease;
}
.mobile-nav-item.active {
  color: var(--text-accent);
}
.mobile-nav-icon {
  font-size: 1.15rem;
  margin-bottom: 2px;
}

/* Floating Back to Top Button */
.floating-top-btn {
  position: fixed;
  bottom: 5rem;
  right: 1.5rem;
  width: 44px;
  height: 44px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  z-index: 80;
  transition: all 0.2s ease;
}
.floating-top-btn:hover {
  transform: translateY(-3px);
  border-color: var(--text-accent);
}

/* ================= Main Layout ================= */
.main-layout {
  max-width: 1360px;
  margin: 0 auto;
  padding: 1.5rem 1.75rem 5rem;
}

/* Hero Banner */
.hero-banner {
  background: linear-gradient(135deg, #1e3a8a 0%, #0369a1 50%, #0f766e 100%);
  border-radius: var(--card-radius);
  color: #ffffff;
  padding: 2.5rem 2.25rem;
  margin-bottom: 1.75rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}
.hero-banner::after {
  content: "ॐ";
  position: absolute;
  right: 2rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 14rem;
  opacity: 0.08;
  pointer-events: none;
  font-family: serif;
}
.hero-tag {
  display: inline-block;
  background: rgba(255, 255, 255, 0.18);
  backdrop-filter: blur(8px);
  padding: 0.35rem 0.85rem;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  margin-bottom: 0.85rem;
  border: 1px solid rgba(255, 255, 255, 0.25);
}
.hero-title {
  font-size: 2.1rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
  margin-bottom: 0.75rem;
}
.hero-desc {
  font-size: 1.05rem;
  opacity: 0.92;
  max-width: 860px;
  line-height: 1.65;
  margin-bottom: 1.5rem;
}
.hero-stats-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}
.stat-pill {
  background: rgba(0, 0, 0, 0.25);
  backdrop-filter: blur(6px);
  padding: 0.5rem 1rem;
  border-radius: 10px;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  border: 1px solid rgba(255, 255, 255, 0.15);
}
.stat-num {
  font-size: 1.15rem;
  font-weight: 800;
  color: #38bdf8;
}
.stat-label {
  font-size: 0.8rem;
  font-weight: 600;
  opacity: 0.9;
}

/* Search & Filter Section */
.search-filter-section {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 1.15rem 1.4rem;
  margin-bottom: 1.75rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.search-box-wrap {
  position: relative;
  display: flex;
  align-items: center;
}
.search-icon {
  position: absolute;
  left: 1rem;
  font-size: 1.1rem;
  color: var(--text-muted);
}
.search-input {
  width: 100%;
  padding: 0.85rem 2.8rem 0.85rem 2.8rem;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  font-size: 0.95rem;
  color: var(--text-main);
  outline: none;
  transition: all 0.2s ease;
  font-family: inherit;
}
.search-input:focus {
  border-color: var(--text-accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
  background: var(--bg-card);
}
.clear-search-btn {
  position: absolute;
  right: 1rem;
  background: transparent;
  border: none;
  font-size: 1rem;
  color: var(--text-muted);
  cursor: pointer;
}

.unit-pills-wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.unit-filter-btn {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.45rem 0.9rem;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.unit-filter-btn:hover {
  background: var(--bg-card-hover);
  color: var(--text-main);
}
.unit-filter-btn.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
  font-weight: 700;
}

/* ================= Tab System ================= */
.tab-pane {
  display: none;
  animation: fadeIn 0.3s ease;
}
.tab-pane.active {
  display: block;
}
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.tab-header-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.5rem;
}
.tab-section-title {
  font-size: 1.45rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--text-main);
}
.tab-section-desc {
  font-size: 0.92rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}
.view-mode-toggles {
  display: flex;
  gap: 0.5rem;
}
.action-btn-sm {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.45rem 0.85rem;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.action-btn-sm:hover:not(:disabled) {
  border-color: var(--text-accent);
  background: var(--bg-card-hover);
}
.action-btn-sm:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}
.action-btn-lg {
  background: linear-gradient(135deg, #1e3a8a, #0284c7);
  border: none;
  color: #ffffff;
  padding: 0.85rem 1.75rem;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 4px 12px rgba(2, 132, 199, 0.3);
}
.action-btn-lg:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(2, 132, 199, 0.4);
}

/* ================= TAB 1: BOOK CARDS & TOPICS ================= */
.units-container {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}
.unit-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all 0.25s ease;
}
.unit-card:hover {
  box-shadow: var(--shadow-md);
}

.unit-card-header {
  padding: 1.4rem 1.6rem;
  background: linear-gradient(to right, rgba(37, 99, 235, 0.05), transparent);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  user-select: none;
}
body.theme-dark .unit-card-header {
  background: linear-gradient(to right, rgba(96, 165, 250, 0.08), transparent);
}
.unit-header-info {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.unit-badge-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.badge-code {
  background: var(--text-accent);
  color: #ffffff;
  padding: 0.2rem 0.55rem;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}
.badge-time {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 600;
}
.unit-card-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1.35;
}
.unit-card-subtitle {
  font-size: 0.88rem;
  color: var(--text-muted);
}
.unit-toggle-icon {
  font-size: 1.35rem;
  color: var(--text-muted);
  transition: transform 0.25s ease;
}
.unit-card.collapsed .unit-toggle-icon {
  transform: rotate(-90deg);
}

.unit-card-body {
  padding: 1.6rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
  transition: all 0.25s ease;
}
.unit-card.collapsed .unit-card-body {
  display: none;
}

.unit-overview-box {
  background: var(--bg-primary);
  border-left: 4px solid var(--text-accent);
  padding: 1rem 1.25rem;
  border-radius: 0 8px 8px 0;
  font-size: 0.95rem;
  line-height: 1.65;
  color: var(--text-main);
}

/* Topic Section */
.topic-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}
.topic-header {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.75rem;
}
.topic-title {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}
.key-concepts-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.concept-tag {
  background: rgba(37, 99, 235, 0.08);
  color: var(--text-accent);
  padding: 0.15rem 0.55rem;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 600;
}
body.theme-dark .concept-tag {
  background: rgba(96, 165, 250, 0.15);
}

/* Textbook Content Typography */
.textbook-prose {
  font-family: var(--font-serif);
  font-size: 0.98rem;
  line-height: 1.85;
  color: var(--text-main);
}
.textbook-prose h3 {
  font-family: var(--font-sans);
  font-size: 1.12rem;
  font-weight: 800;
  color: var(--text-main);
  margin: 1.25rem 0 0.6rem;
  border-left: 3px solid var(--accent-gold);
  padding-left: 0.6rem;
}
.textbook-prose h4 {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-accent);
  margin: 1rem 0 0.4rem;
}
.textbook-prose p {
  margin-bottom: 0.85rem;
}
.textbook-prose ul, .textbook-prose ol {
  margin: 0.6rem 0 1rem 1.4rem;
}
.textbook-prose li {
  margin-bottom: 0.45rem;
}
.textbook-prose strong {
  font-weight: 700;
  color: var(--text-main);
}

/* Markdown Tables & Responsive Wrappers */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin: 1.25rem 0;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}
.table-responsive table {
  margin: 0 !important;
  border: none !important;
}
.textbook-prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
  font-family: var(--font-sans);
  font-size: 0.88rem;
  background: var(--bg-primary);
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border-color);
  min-width: 480px;
}
.textbook-prose th {
  background: rgba(37, 99, 235, 0.1);
  color: var(--text-accent);
  font-weight: 700;
  text-align: left;
  padding: 0.65rem 0.9rem;
  border-bottom: 1px solid var(--border-color);
}
body.theme-dark .textbook-prose th {
  background: rgba(96, 165, 250, 0.15);
}
.textbook-prose td {
  padding: 0.65rem 0.9rem;
  border-bottom: 1px solid var(--border-color);
}
.textbook-prose tr:last-child td {
  border-bottom: none;
}

/* Inline Diagram Box */
.inline-diagram-box {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.65rem;
  margin-top: 1rem;
}
.inline-diagram-img {
  max-width: 100%;
  max-height: 480px;
  object-fit: contain;
  border-radius: 6px;
  cursor: zoom-in;
  transition: transform 0.2s ease;
  background: #ffffff;
}
.inline-diagram-img:hover {
  transform: scale(1.02);
}
.inline-diagram-caption {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-muted);
  text-align: center;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* ================= TAB 2: LAB & ANIMATIONS ================= */
.lab-subnav-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
}
.lab-tab-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.6rem 1.1rem;
  border-radius: 9px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.lab-tab-btn:hover {
  background: var(--bg-card-hover);
  color: var(--text-main);
}
.lab-tab-btn.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.25);
}

.lab-model-card {
  display: none;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  animation: fadeIn 0.25s ease;
}
.lab-model-card.active {
  display: block;
}

.lab-model-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1.25rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1.25rem;
  margin-bottom: 1.5rem;
}
.lab-model-header h4 {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
}
.lab-model-header p {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}

/* Cardiac Simulator Layout */
.cardiac-controls {
  display: flex;
  align-items: center;
  gap: 1rem;
}
.sound-toggle-btn {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
}
.cardiac-sim-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.75rem;
}

.sim-visual-box {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  position: relative;
}
.cardiac-svg {
  width: 100%;
  max-width: 440px;
  height: auto;
}
.heart-outer-silhouette {
  fill: rgba(239, 68, 68, 0.06);
  stroke: rgba(239, 68, 68, 0.2);
  stroke-width: 3;
}
.vessel-deox {
  fill: #3b82f6;
  opacity: 0.85;
}
.vessel-ox {
  fill: #ef4444;
  opacity: 0.85;
}
.svg-vessel-text {
  fill: #ffffff;
  font-size: 11px;
  font-weight: 700;
  text-anchor: middle;
}
.chamber {
  stroke-width: 3;
  transition: all 0.25s ease;
}
.chamber-ra {
  fill: #dbeafe;
  stroke: #2563eb;
}
body.theme-dark .chamber-ra {
  fill: #1e3a8a;
  stroke: #3b82f6;
}
.chamber-rv {
  fill: #bfdbfe;
  stroke: #1d4ed8;
}
body.theme-dark .chamber-rv {
  fill: #172554;
  stroke: #2563eb;
}
.chamber-la {
  fill: #fee2e2;
  stroke: #dc2626;
}
body.theme-dark .chamber-la {
  fill: #7f1d1d;
  stroke: #ef4444;
}
.chamber-lv {
  fill: #fecaca;
  stroke: #b91c1c;
}
body.theme-dark .chamber-lv {
  fill: #450a0a;
  stroke: #dc2626;
}
.chamber-title {
  font-size: 12px;
  font-weight: 800;
  text-anchor: middle;
  fill: var(--text-main);
}
.chamber-sub {
  font-size: 9px;
  font-weight: 600;
  text-anchor: middle;
  fill: var(--text-muted);
}
.chamber-vol {
  font-size: 8.5px;
  text-anchor: middle;
  fill: var(--text-muted);
}
.septum-wall {
  fill: #cbd5e1;
}
body.theme-dark .septum-wall {
  fill: #334155;
}
.septum-text {
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.2em;
  fill: #64748b;
  text-anchor: middle;
}
.valve {
  stroke: #f59e0b;
  stroke-width: 5;
  stroke-linecap: round;
  transition: all 0.2s ease;
}
.valve.open {
  stroke-dasharray: 6 6;
  opacity: 0.4;
}
.valve-text {
  font-size: 9px;
  font-weight: 700;
  fill: #d97706;
  text-anchor: middle;
}

/* Cardiac Phase Glow Pulse */
.chamber.contracting {
  filter: drop-shadow(0 0 12px rgba(239, 68, 68, 0.6));
  transform-origin: center;
  transform: scale(0.96);
}

.heartbeat-pulse-badge {
  margin-top: 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  box-shadow: var(--shadow-sm);
}
.heart-pulse-icon {
  animation: heartPulse 0.8s infinite;
}
@keyframes heartPulse {
  0% { transform: scale(1); }
  15% { transform: scale(1.3); }
  30% { transform: scale(1); }
  45% { transform: scale(1.15); }
  60% { transform: scale(1); }
}

/* Live Metrics Box */
.metrics-heading {
  font-size: 0.95rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 0.85rem;
}
.metric-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.85rem;
}
.metric-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  padding: 0.85rem;
  border-radius: 10px;
  display: flex;
  flex-direction: column;
}
.metric-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
}
.metric-val {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  margin: 0.2rem 0;
}
.metric-sub {
  font-size: 0.72rem;
  color: var(--text-muted);
}
.text-rose { color: var(--accent-rose) !important; }
.text-emerald { color: var(--accent-emerald) !important; }
.text-accent { color: var(--text-accent) !important; }

.cardiac-phase-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}
.cardiac-phase-item {
  padding: 0.6rem 0.85rem;
  border-radius: 8px;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  font-size: 0.82rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all 0.2s ease;
}
.cardiac-phase-item.active {
  background: rgba(37, 99, 235, 0.12);
  border-color: var(--text-accent);
  font-weight: 700;
  color: var(--text-accent);
}

/* Pranayama Pacer Layout */
.pacer-controls-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}
.styled-select {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.45rem 0.85rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  outline: none;
}
.pacer-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}
.pacer-visual-box {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 2rem 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.breath-circle-container {
  width: 240px;
  height: 240px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
}
.breath-circle {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: radial-gradient(circle, #38bdf8 0%, #0284c7 70%, #1e3a8a 100%);
  box-shadow: 0 0 30px rgba(56, 189, 248, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  transition: transform 1s ease-in-out, box-shadow 1s ease-in-out;
}
.circle-inner-content {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.pacer-stage-label {
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}
.pacer-timer {
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.1;
  font-family: var(--font-code);
}
.pacer-ratio-label {
  font-size: 0.72rem;
  opacity: 0.85;
  font-weight: 600;
}

.lung-indicators-row {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  width: 100%;
}
.indicator-pill {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 0.45rem 0.85rem;
  border-radius: 8px;
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
}
.indicator-title {
  color: var(--text-muted);
  font-weight: 600;
}
.indicator-state {
  font-weight: 700;
  color: var(--text-main);
}

.info-callout-card {
  background: var(--bg-primary);
  border-left: 4px solid var(--accent-emerald);
  padding: 1rem 1.25rem;
  border-radius: 0 10px 10px 0;
  font-size: 0.92rem;
  line-height: 1.65;
}
.volume-bar-row {
  margin-bottom: 0.85rem;
}
.vol-label {
  font-size: 0.78rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  color: var(--text-muted);
}
.vol-bar-bg {
  width: 100%;
  height: 8px;
  background: var(--border-color);
  border-radius: 4px;
  overflow: hidden;
}
.vol-bar-fill {
  height: 100%;
  border-radius: 4px;
  transition: width 0.3s ease;
}

/* Nephron Simulator */
.nephron-stepper-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 1.5rem;
}
.stepper-nav {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.step-nav-btn {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  padding: 0.85rem 1rem;
  border-radius: 10px;
  text-align: left;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  transition: all 0.2s ease;
}
.step-nav-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--text-accent);
}
.step-nav-btn.active {
  background: rgba(37, 99, 235, 0.1);
  border-color: var(--text-accent);
}
.step-num-badge {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text-accent);
}
.step-nav-title {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-main);
}

.stepper-content-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* Posture Selector */
.posture-selector-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
}
.posture-btn {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.55rem 1rem;
  border-radius: 8px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.posture-btn.active {
  background: var(--accent-gold);
  color: #ffffff;
  border-color: var(--accent-gold);
}
.posture-display-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* Asana System Explorer */
.system-pills-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
}
.system-pill-btn {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.55rem 1rem;
  border-radius: 8px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.45rem;
  transition: all 0.2s ease;
}
.system-pill-btn.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
}
.system-impact-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* ================= TAB 3: IMPORTANT POINTS ================= */
.points-subnav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.points-sub-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.5rem 0.95rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.points-sub-btn.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
}

.points-subpane {
  display: none;
  animation: fadeIn 0.25s ease;
}
.points-subpane.active {
  display: block;
}

.tables-vertical-stack {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}
.custom-data-table-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  width: 100%;
}
.table-card-header {
  padding: 1rem 1.4rem;
  background: rgba(37, 99, 235, 0.06);
  border-bottom: 1px solid var(--border-color);
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--text-main);
}
.custom-table-wrapper {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.custom-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  min-width: 520px;
}
.custom-table th {
  background: var(--bg-primary);
  color: var(--text-accent);
  padding: 0.75rem 1rem;
  font-weight: 700;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}
.custom-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-main);
}
.custom-table tr:last-child td {
  border-bottom: none;
}

.mnemonics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.25rem;
}
.mnemonic-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.mnemonic-title {
  font-size: 0.95rem;
  font-weight: 800;
  color: var(--text-main);
}
.mnemonic-phrase {
  background: rgba(217, 119, 6, 0.1);
  color: #b45309;
  padding: 0.5rem 0.85rem;
  border-radius: 8px;
  font-weight: 800;
  font-size: 0.95rem;
  border: 1px solid rgba(217, 119, 6, 0.25);
}
body.theme-dark .mnemonic-phrase {
  background: rgba(251, 191, 36, 0.15);
  color: #fde68a;
}
.mnemonic-expl {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* 3D Flashcard Stage */
.flashcard-controls-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}
.flashcard-counter-label {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-muted);
}
.flashcard-stage {
  perspective: 1200px;
  display: flex;
  justify-content: center;
  margin-bottom: 2rem;
}
.flashcard-card {
  width: 100%;
  max-width: 620px;
  height: 320px;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4, 0.2, 0.2, 1);
  cursor: pointer;
}
.flashcard-card.flipped {
  transform: rotateY(180deg);
}
.card-face {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: var(--card-radius);
  border: 1px solid var(--border-color);
  padding: 2rem 2.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-lg);
}
.card-face-front {
  background: var(--bg-card);
}
.card-face-back {
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.08), rgba(2, 132, 199, 0.08)), var(--bg-card);
  transform: rotateY(180deg);
  border-color: var(--text-accent);
}
.card-category-badge {
  display: inline-block;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  padding: 0.25rem 0.65rem;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-accent);
  align-self: flex-start;
}
.card-prompt-text {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.5;
  text-align: center;
}
.card-answer-text {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-main);
  line-height: 1.7;
  text-align: center;
}
.card-tap-hint {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  text-align: center;
}

/* ================= TAB 4: EXAM TEST CENTER ================= */
.exam-subnav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.exam-sub-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.5rem 0.95rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.exam-sub-btn.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
}
.exam-subpane {
  display: none;
  animation: fadeIn 0.25s ease;
}
.exam-subpane.active {
  display: block;
}

/* MCQ Quiz Layout */
.quiz-status-header {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1rem 1.4rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
}
.quiz-progress-wrap {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex: 1;
  max-width: 480px;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-muted);
}
.progress-bar-bg {
  flex: 1;
  height: 8px;
  background: var(--bg-primary);
  border-radius: 4px;
  overflow: hidden;
  border: 1px solid var(--border-color);
}
.progress-bar-fill {
  height: 100%;
  background: var(--text-accent);
  border-radius: 4px;
  transition: width 0.25s ease;
}
.quiz-score-pill {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-main);
}

.mcq-question-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 2rem 2.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}
.mcq-q-title {
  font-size: 1.15rem;
  font-weight: 800;
  line-height: 1.5;
  color: var(--text-main);
}
.mcq-options-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}
.mcq-option-btn {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.85rem 1.25rem;
  border-radius: 10px;
  text-align: left;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: 0.85rem;
}
.mcq-option-btn:hover:not(.locked) {
  background: var(--bg-card-hover);
  border-color: var(--text-accent);
}
.mcq-option-btn.correct {
  background: rgba(16, 185, 129, 0.15) !important;
  border-color: #10b981 !important;
  color: #047857 !important;
  font-weight: 700;
}
body.theme-dark .mcq-option-btn.correct {
  color: #34d399 !important;
}
.mcq-option-btn.incorrect {
  background: rgba(239, 68, 68, 0.15) !important;
  border-color: #ef4444 !important;
  color: #b91c1c !important;
}
body.theme-dark .mcq-option-btn.incorrect {
  color: #f87171 !important;
}
.mcq-option-btn.locked {
  cursor: default;
}

.mcq-explanation-box {
  background: var(--bg-primary);
  border-left: 4px solid var(--text-accent);
  padding: 1rem 1.25rem;
  border-radius: 0 8px 8px 0;
  font-size: 0.9rem;
  line-height: 1.6;
  animation: fadeIn 0.2s ease;
}

.quiz-nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 1.5rem;
}

/* Intext Questions Grid */
.intext-filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}
.filter-pill {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.4rem 0.85rem;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
}
.filter-pill.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
}
.intext-questions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 1.25rem;
}
.intext-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1rem;
}
.intext-q-text {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.5;
}
.intext-answer-revealed {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  padding: 0.75rem 1rem;
  border-radius: 8px;
  font-size: 0.88rem;
  line-height: 1.6;
}
.reveal-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-accent);
  padding: 0.45rem 0.85rem;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  align-self: flex-start;
  transition: all 0.2s ease;
}
.reveal-btn:hover {
  background: rgba(37, 99, 235, 0.08);
}

/* 16-Mark Essay Bank */
.essay-selector-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}
.essay-tab-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.55rem 0.95rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}
.essay-tab-btn.active {
  background: var(--accent-emerald);
  color: #ffffff;
  border-color: var(--accent-emerald);
}
.essay-display-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 2rem 2.25rem;
  box-shadow: var(--shadow-sm);
}
.essay-question-title {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 1rem;
}
.essay-synopsis-box {
  background: rgba(16, 185, 129, 0.08);
  border: 1px solid rgba(16, 185, 129, 0.25);
  padding: 1.25rem;
  border-radius: 10px;
  margin-bottom: 1.5rem;
}
.synopsis-title {
  font-size: 0.95rem;
  font-weight: 800;
  color: #047857;
  margin-bottom: 0.5rem;
}
body.theme-dark .synopsis-title {
  color: #34d399;
}
.synopsis-list {
  list-style: none;
  font-size: 0.88rem;
  line-height: 1.7;
}
.diagram-tip-box {
  background: rgba(217, 119, 6, 0.08);
  border-left: 4px solid var(--accent-gold);
  padding: 0.85rem 1.15rem;
  border-radius: 0 8px 8px 0;
  font-size: 0.88rem;
  margin-bottom: 1.5rem;
}

/* Timed Mock Exam */
.mock-intro-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 2.5rem;
  text-align: center;
  max-width: 680px;
  margin: 2rem auto;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
}
.mock-rules-list {
  list-style: none;
  text-align: left;
  font-size: 0.92rem;
  line-height: 1.8;
}
.mock-timer-bar {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 0.85rem 1.4rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.95rem;
  font-weight: 700;
}
.mock-result-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 2.5rem;
  text-align: center;
  max-width: 680px;
  margin: 2rem auto;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
}

/* ================= TAB 5: GALLERY ================= */
.gallery-filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}
.gallery-pill {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.45rem 0.9rem;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.gallery-pill.active {
  background: var(--text-accent);
  color: #ffffff;
  border-color: var(--text-accent);
}
.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}
.gallery-item-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  transition: all 0.25s ease;
  cursor: pointer;
}
.gallery-item-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--text-accent);
}
.gallery-thumb-box {
  width: 100%;
  height: 200px;
  background: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}
.gallery-thumb-img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}
.gallery-info-box {
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.gallery-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.35;
}
.gallery-page-tag {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
}

/* ================= Lightbox Modal ================= */
.lightbox-modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.85);
  backdrop-filter: blur(8px);
  z-index: 200;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  animation: fadeIn 0.2s ease;
}
.lightbox-modal.active {
  display: flex;
}
.lightbox-content-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  max-width: 92vw;
  max-height: 92vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.25rem;
  position: relative;
  box-shadow: var(--shadow-xl);
}
.lightbox-close-btn {
  position: absolute;
  top: 0.85rem;
  right: 0.85rem;
  background: rgba(0, 0, 0, 0.1);
  border: none;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  color: var(--text-main);
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}
body.theme-dark .lightbox-close-btn {
  background: rgba(255, 255, 255, 0.1);
}
.lightbox-img {
  max-width: 100%;
  max-height: 75vh;
  object-fit: contain;
  border-radius: 8px;
  background: #ffffff;
}
.lightbox-caption {
  margin-top: 0.85rem;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text-main);
  text-align: center;
}

/* ================= Responsive Rules ================= */
@media (max-width: 1024px) {
  .cardiac-sim-layout,
  .pacer-layout,
  .nephron-stepper-layout {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }
  .cardiac-svg {
    max-width: 100%;
  }
}

@media (max-width: 768px) {
  .desktop-nav {
    display: none;
  }
  .mobile-bottom-nav {
    display: flex;
    padding-bottom: max(0.4rem, env(safe-area-inset-bottom));
  }
  .floating-top-btn {
    bottom: max(4.8rem, calc(4.5rem + env(safe-area-inset-bottom)));
    right: 1rem;
    width: 40px;
    height: 40px;
    font-size: 1rem;
  }
  .app-header {
    padding: 0.65rem 1rem;
  }
  .hero-banner {
    padding: 1.5rem 1.15rem;
    margin-bottom: 1.25rem;
  }
  .hero-banner::after {
    font-size: 8rem;
    right: 0.5rem;
  }
  .hero-title {
    font-size: clamp(1.4rem, 5vw, 1.8rem);
  }
  .hero-desc {
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 1.15rem;
  }
  .hero-stats-row {
    gap: 0.5rem;
  }
  .stat-pill {
    padding: 0.4rem 0.75rem;
    font-size: 0.75rem;
  }
  .stat-num {
    font-size: 1rem;
  }
  .desktop-only {
    display: none !important;
  }
  .main-layout {
    padding: 0.85rem 0.85rem max(6rem, calc(5.5rem + env(safe-area-inset-bottom)));
  }
  .search-filter-section {
    padding: 1rem;
    gap: 0.85rem;
  }
  .search-input {
    font-size: 0.88rem;
    padding: 0.75rem 2.4rem 0.75rem 2.5rem;
  }
  .unit-card-header {
    padding: 1.15rem 1.15rem;
  }
  .unit-card-title {
    font-size: 1.1rem;
  }
  .unit-card-body {
    padding: 1.15rem;
    gap: 1.4rem;
  }
  .topic-card {
    padding: 1.15rem;
  }
  .topic-title {
    font-size: 1.05rem;
  }
  .textbook-prose {
    font-size: 0.92rem;
    line-height: 1.75;
  }
  .intext-questions-grid {
    grid-template-columns: 1fr;
  }
  .mnemonics-grid {
    grid-template-columns: 1fr;
  }
  .gallery-grid {
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1rem;
  }
  .metric-grid {
    grid-template-columns: 1fr;
  }
  .flashcard-card {
    height: auto;
    min-height: 300px;
    max-height: 480px;
  }
  .card-face {
    padding: 1.5rem 1.25rem;
    overflow-y: auto;
  }
  .card-prompt-text {
    font-size: 1.1rem;
  }
  .card-answer-text {
    font-size: 0.95rem;
    line-height: 1.6;
  }
  .mcq-question-card,
  .essay-display-card,
  .lab-model-card {
    padding: 1.25rem 1.15rem;
  }
  .mcq-option-btn {
    padding: 0.75rem 1rem;
    font-size: 0.88rem;
    min-height: 48px;
  }
  .cardiac-controls,
  .pacer-controls-row {
    flex-direction: column;
    align-items: flex-start;
    width: 100%;
    gap: 0.65rem;
  }
  .breath-circle-container {
    width: 200px;
    height: 200px;
  }
  .breath-circle {
    width: 120px;
    height: 120px;
  }
  .pacer-timer {
    font-size: 1.8rem;
  }
  /* Mobile touch target minimum size */
  .unit-filter-btn,
  .lab-tab-btn,
  .points-sub-btn,
  .exam-sub-btn,
  .gallery-pill,
  .filter-pill,
  .action-btn-sm {
    min-height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .logo-text h1 {
    font-size: 1rem;
  }
  .logo-text p {
    display: none;
  }
  .logo-badge {
    width: 36px;
    height: 36px;
    font-size: 1.25rem;
  }
  .hero-tag {
    font-size: 0.72rem;
  }
  .hero-title {
    font-size: 1.35rem;
  }
  .stat-pill {
    flex: 1 1 calc(50% - 0.5rem);
    justify-content: center;
  }
  .gallery-grid {
    grid-template-columns: 1fr;
  }
  .quiz-status-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.65rem;
  }
  .quiz-progress-wrap {
    width: 100%;
  }
  .quiz-nav-row {
    flex-wrap: wrap;
    gap: 0.5rem;
  }
}

/* Touch active micro-animations */
button:active {
  transform: scale(0.97);
}

/* Print Styles */
@media print {
  .app-header,
  .mobile-bottom-nav,
  .floating-top-btn,
  .search-filter-section,
  .view-mode-toggles,
  .lab-subnav-bar,
  .points-subnav,
  .exam-subnav {
    display: none !important;
  }
  body {
    background: #ffffff !important;
    color: #000000 !important;
  }
  .unit-card {
    border: none !important;
    box-shadow: none !important;
    page-break-inside: avoid;
  }
  .unit-card.collapsed .unit-card-body {
    display: flex !important;
  }
}