/* ==========================================================================
   PhysioEng 3D: Stylesheet
   Strict 100% Clean White / Light Theme ONLY
   Body: #f8fafc | Cards: #ffffff | Text: #0f172a | Borders: #e2e8f0
   ========================================================================== */

:root {
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-subtle: #f1f5f9;
  --bg-hover: #e2e8f0;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  
  --border-color: #e2e8f0;
  --border-focus: #3b82f6;
  
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-subtle: #eff6ff;
  
  --accent-amber: #d97706;
  --accent-amber-subtle: #fef3c7;
  
  --accent-emerald: #059669;
  --accent-emerald-subtle: #d1fae5;
  
  --accent-purple: #7c3aed;
  --accent-purple-subtle: #f5f3ff;
  
  --accent-rose: #e11d48;
  --accent-rose-subtle: #ffe4e6;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
  
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --font-hindi: 'Inter', system-ui, sans-serif;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
}

/* Reset & Base Setup */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg-main);
  color: var(--text-primary);
  overflow-x: hidden;
  max-width: 100vw;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  max-width: 100vw;
  width: 100%;
}

/* Hindi text class */
.hindi-text {
  font-family: var(--font-hindi);
  color: var(--text-secondary);
  line-height: 1.65;
  font-size: 0.95rem;
}

/* Header Styles */
.app-header {
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  padding: 1.25rem 2rem;
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 50;
}

.header-container {
  max-width: 1440px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.brand-badge {
  background: linear-gradient(135deg, #1e40af, #2563eb);
  color: #ffffff;
  font-weight: 800;
  font-size: 1.15rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  letter-spacing: -0.02em;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.25);
}

.brand-titles .brand-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.015em;
}

.brand-titles .brand-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.header-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Badges */
.badge {
  display: inline-flex;
  align-items: center;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  border: 1px solid transparent;
}

.badge-accent {
  background-color: var(--primary-subtle);
  color: var(--primary);
  border-color: #bfdbfe;
}

.badge-status {
  background-color: var(--accent-emerald-subtle);
  color: var(--accent-emerald);
  border-color: #a7f3d0;
}

.badge-secondary {
  background-color: var(--bg-subtle);
  color: var(--text-secondary);
  border-color: var(--border-color);
}

.pill-pill {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  background: var(--bg-subtle);
  color: var(--primary);
  border: 1px solid var(--border-color);
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-full);
  font-weight: 600;
}

/* App Main Layout with Sticky Left Sidebar */
.app-layout-wrapper {
  display: flex;
  min-height: calc(100vh - 73px);
  width: 100%;
  position: relative;
}

/* Left Sidebar Navigation */
.app-sidebar {
  width: 320px;
  min-width: 320px;
  max-width: 320px;
  background-color: #ffffff;
  border-right: 1px solid var(--border-color);
  height: calc(100vh - 73px);
  position: sticky;
  top: 73px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  z-index: 40;
  box-shadow: 1px 0 3px rgba(0,0,0,0.02);
}

.sidebar-header {
  padding: 1.25rem 1.25rem 0.75rem;
  border-bottom: 1px solid var(--border-color);
  background-color: var(--bg-subtle);
}

.sidebar-heading {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.sidebar-chapters-list {
  padding: 0.75rem 0.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  flex: 1;
}

/* Chapter Accordion Group */
.chapter-accordion-group {
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  transition: all 0.15s ease-in-out;
}

.chapter-accordion-group.open {
  border-color: var(--border-color);
  background-color: #ffffff;
}

.chapter-header-btn {
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  padding: 0.75rem 0.85rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  transition: background-color 0.15s ease;
  font-family: var(--font-sans);
}

.chapter-header-btn:hover {
  background-color: var(--bg-subtle);
}

.chapter-title-group {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.chapter-icon {
  font-size: 1.1rem;
}

.chapter-name {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.accordion-arrow {
  font-size: 0.75rem;
  color: var(--text-muted);
  transition: transform 0.2s ease;
}

.chapter-accordion-group.open .accordion-arrow {
  transform: rotate(90deg);
}

/* Chapter Sub-tabs List */
.chapter-subtabs {
  display: none;
  flex-direction: column;
  padding: 0.25rem 0.4rem 0.6rem 1.5rem;
  gap: 0.25rem;
}

.chapter-accordion-group.open .chapter-subtabs {
  display: flex;
}

.sidebar-tab-btn {
  background: transparent;
  border: none;
  text-align: left;
  padding: 0.55rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.825rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.15s ease;
  font-family: var(--font-sans);
  line-height: 1.35;
}

.sidebar-tab-btn:hover {
  background-color: var(--bg-subtle);
  color: var(--text-primary);
}

.sidebar-tab-btn.active {
  background-color: var(--primary-subtle);
  color: var(--primary);
  border-left: 3px solid var(--primary);
}

.sidebar-tab-num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  background-color: var(--bg-subtle);
  color: var(--text-secondary);
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
  border: 1px solid var(--border-color);
  white-space: nowrap;
}

.sidebar-tab-btn.active .sidebar-tab-num {
  background-color: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

.sidebar-tab-label {
  white-space: normal;
}

/* Coming Soon Chapter Item */
.chapter-accordion-group.disabled .chapter-header-btn {
  opacity: 0.6;
  cursor: default;
}

.chapter-accordion-group.disabled:hover {
  background: transparent;
}

.badge-coming {
  font-size: 0.675rem;
  padding: 0.15rem 0.45rem;
  background-color: var(--bg-subtle);
  color: var(--text-muted);
  border-radius: var(--radius-full);
  font-weight: 600;
}

/* Mobile Sidebar Toggle Button */
.mobile-sidebar-toggle {
  display: none;
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  padding: 0.5rem 0.85rem;
  border-radius: var(--radius-md);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
}

/* Main Layout Viewport */
.main-viewport {
  flex: 1;
  max-width: calc(100vw - 320px);
  padding: 2rem 2rem 4rem;
  overflow-y: auto;
  background-color: var(--bg-main);
  min-height: calc(100vh - 73px);
  width: 100%;
}

.tab-pane {
  display: none;
  animation: fadeIn 0.2s ease-in-out;
}

.tab-pane.active {
  display: block;
}

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

/* Cards & Sections */
.section-intro-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem 2rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
}

.intro-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.85rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.intro-header h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  position: relative;
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.card-header h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}

.card-header h4 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
}

.section-margin-top {
  margin-top: 2rem;
}

/* Grids */
.module-grid {
  display: grid;
  gap: 1.5rem;
}

.grid-2col {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.math-cards-grid {
  display: grid;
  gap: 1.5rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 0.15s ease-in-out;
  border: 1px solid transparent;
  font-family: var(--font-sans);
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
}

.btn-secondary {
  background-color: var(--bg-subtle);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--bg-hover);
}

.btn-outline {
  background-color: #ffffff;
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-outline:hover {
  background-color: var(--bg-subtle);
  border-color: #cbd5e1;
}

.btn-block {
  width: 100%;
}

.btn-sm {
  font-size: 0.8rem;
  padding: 0.35rem 0.75rem;
}

/* Viewport 3D Three.js */
.viewport-3d-wrapper {
  position: relative;
  width: 100%;
  height: 380px;
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.three-viewport {
  width: 100%;
  height: 100%;
  display: block;
}

.chamber-overlay {
  position: absolute;
  top: 12px;
  left: 12px;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  pointer-events: none;
}

.legend-badge {
  background-color: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--border-color);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.45rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}

.dot-blue { background-color: #2563eb; }
.dot-amber { background-color: #d97706; }
.dot-green { background-color: #059669; }
.dot-purple { background-color: #7c3aed; }

.card-footer-info {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

/* Energy Canvas Wrapper */
.energy-canvas-wrapper {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.5rem;
  margin-bottom: 1.25rem;
  display: flex;
  justify-content: center;
}

#energyBarrierCanvas {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Metrics Grid */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.metric-box {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem 1rem;
}

.metric-title {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.25rem;
}

.metric-val {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.metric-sub {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}

.info-callout {
  background-color: var(--primary-subtle);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 1rem 1.25rem;
}

.callout-title {
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--primary);
  margin-bottom: 0.35rem;
}

/* Math Blocks & KaTeX */
.math-block {
  overflow-x: auto;
  padding: 0.75rem 0.5rem;
  text-align: center;
  font-size: 1.05rem;
  color: var(--text-primary);
}

.katex-display {
  margin: 0.5rem 0 !important;
}

/* Time Series & Chart Controls */
.sim-dashboard-layout {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 1.5rem;
}

.sim-controls-panel {
  display: flex;
  flex-direction: column;
  gap: 1.15rem;
}

.sim-controls-panel h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.5rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.control-label-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.825rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.slider-display {
  font-family: var(--font-mono);
  font-size: 0.825rem;
  color: var(--primary);
  font-weight: 700;
}

input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 4px;
  background: #cbd5e1;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  transition: transform 0.1s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}

.equilibrium-calc-box {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.825rem;
}

.calc-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.calc-row strong {
  font-family: var(--font-mono);
  color: var(--text-primary);
}

.chart-container-wrapper {
  position: relative;
  width: 100%;
  height: 380px;
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.75rem;
}

.chart-container-wrapper canvas {
  width: 100% !important;
  height: 100% !important;
}

.chart-caption-box {
  margin-top: 1rem;
}

/* Proof Card */
.proof-card {
  background-color: #f0fdf4;
  border: 1px solid #bbf7d0;
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
}

.proof-card h4 {
  color: #166534;
  font-size: 0.9rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

/* Lineweaver Burk Details */
.analytical-details-panel {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.intercepts-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.intercept-cell {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem;
}

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

.int-value {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--primary);
  margin: 0.25rem 0;
}

.int-desc {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

/* Preset Buttons */
.preset-buttons-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

/* Delivery Metrics */
.transport-analysis-card {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.delivery-metrics-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.full-width {
  grid-column: span 2;
}

.text-accent {
  color: var(--accent-emerald) !important;
}

/* Data Table for Exercise E */
.dataset-panel {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.dataset-header-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.table-responsive {
  max-height: 220px;
  overflow-y: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.825rem;
}

.data-table th {
  background-color: var(--bg-subtle);
  color: var(--text-secondary);
  font-weight: 600;
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
}

.data-table td {
  padding: 0.45rem 0.75rem;
  border-bottom: 1px solid var(--border-color);
  font-family: var(--font-mono);
  color: var(--text-primary);
}

.data-table tbody tr:hover {
  background-color: var(--bg-subtle);
}

.regression-summary-box {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem 1rem;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.85rem;
}

.reg-stat {
  display: flex;
  flex-direction: column;
}

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

.stat-val {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--primary);
}

.stat-ref {
  font-size: 0.7rem;
  color: var(--text-secondary);
}

/* Inhibition Sandbox Layout */
.inhibition-sandbox-layout {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 1.5rem;
}

.radio-toggle-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  background-color: var(--bg-subtle);
  padding: 0.6rem;
  border-radius: var(--radius-md);
}

.radio-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
}

.apparent-metrics-box {
  background-color: var(--primary-subtle);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius-md);
  padding: 0.85rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.825rem;
}

.dual-inhibition-charts {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.chart-header-mini {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  text-align: center;
}

.chart-container-wrapper-half {
  position: relative;
  width: 100%;
  height: 320px;
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.5rem;
}

.chart-container-wrapper-half canvas {
  width: 100% !important;
  height: 100% !important;
}

/* Schematics Flow */
.schematic-flow {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.75rem 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
  margin-bottom: 1rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
}

.flow-step {
  color: var(--text-primary);
}

.flow-or {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-style: italic;
}

.warning-step {
  color: var(--accent-amber);
}

.danger-step {
  color: var(--accent-rose);
}

/* Notes Section in Tab 1.5 */
.notes-content {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.components-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
  margin-top: 0.5rem;
}

.comp-card {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
}

.comp-card h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

/* Exercises Accordion / Cards */
.exercises-accordion {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin-top: 2rem;
}

.exercise-card {
  padding: 0;
  overflow: hidden;
}

.exercise-header {
  background-color: #ffffff;
  border-bottom: 1px solid var(--border-color);
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.ex-badge {
  background-color: var(--primary);
  color: #ffffff;
  font-weight: 800;
  font-size: 0.85rem;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-sm);
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.ex-title h4 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.exercise-body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.problem-statement {
  background-color: var(--bg-subtle);
  border-left: 4px solid var(--accent-amber);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 1rem 1.25rem;
  font-size: 0.95rem;
  color: var(--text-primary);
  line-height: 1.6;
}

.step-by-step {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.step-by-step h5 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--primary);
  margin-top: 0.5rem;
/* Clinical Case Ledger Card Styles */
.clinical-case-card {
  border: 1px solid #bfdbfe;
  background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  margin-top: 1.75rem;
}

.clinical-badge {
  background-color: #fee2e2;
  color: #b91c1c;
  border-color: #fca5a5;
  font-weight: 700;
}

.clinical-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
  margin-top: 0.5rem;
}

.clinical-box {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  box-shadow: 0 1px 2px rgba(0,0,0,0.03);
}

.clinical-box h5 {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--primary);
  margin-bottom: 0.4rem;
}

.clinical-box.warning-box h5 {
  color: #b45309;
}

.clinical-box.danger-box h5 {
  color: #be123c;
}

.clinical-box.calc-box h5 {
  color: #047857;
}

.calc-breakdown-list {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  font-size: 0.825rem;
}

.calc-breakdown-list li {
  list-style: none;
  display: flex;
  justify-content: space-between;
  border-bottom: 1px dashed #e2e8f0;
  padding-bottom: 0.25rem;
}

.calc-breakdown-list strong {
  font-family: var(--font-mono);
  color: var(--text-primary);
}

/* Terminology Breakdown Cards */
.term-breakdown-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
  margin-top: 1.25rem;
  margin-bottom: 1.5rem;
}

.term-card {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.15rem;
  border-top: 3px solid var(--primary);
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}

.term-etymology {
  font-family: var(--font-mono);
  font-size: 0.775rem;
  color: var(--primary);
  background-color: var(--primary-subtle);
  display: inline-block;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
  margin-bottom: 0.5rem;
  font-weight: 600;
}

.term-card h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
}

.term-meaning {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Formal Balance Derivation Box */
.derivation-container {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-top: 1rem;
}

.derivation-step-item {
  border-left: 3px solid var(--primary);
  padding-left: 1rem;
  margin-bottom: 1.25rem;
}

.derivation-step-item:last-child {
  margin-bottom: 0;
}

.derivation-step-item h5 {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 0.25rem;
}

/* Chapter 2 Specific Styles */
.voltmeter-display-box {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  color: #ffffff;
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin-top: 1rem;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.15);
}

.voltmeter-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #94a3b8;
  font-weight: 600;
  margin-bottom: 0.35rem;
}

.voltmeter-value {
  font-family: var(--font-mono);
  font-size: 2.25rem;
  font-weight: 800;
  color: #38bdf8;
  letter-spacing: -0.02em;
}

.voltmeter-sub {
  font-size: 0.75rem;
  color: #cbd5e1;
  margin-top: 0.35rem;
}

/* 2-Compartment Tank Visualizer */
.compartment-tank-wrapper {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.tank-container {
  display: flex;
  height: 240px;
  border: 3px solid #334155;
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
  background-color: #f1f5f9;
}

.tank-compartment {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 0.75rem;
  position: relative;
  transition: all 0.3s ease;
}

.tank-left {
  background-color: rgba(37, 99, 235, 0.04);
  border-right: 3px dashed #64748b;
}

.tank-right {
  background-color: rgba(5, 150, 105, 0.04);
}

.tank-label {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-primary);
  text-align: center;
  background-color: #ffffff;
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.tank-ions-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  justify-content: center;
  align-items: center;
  flex: 1;
  padding: 0.5rem;
}

.ion-pill {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  padding: 0.2rem 0.45rem;
  border-radius: var(--radius-full);
}

.ion-k { background-color: #dbeafe; color: #1e40af; border: 1px solid #bfdbfe; }
.ion-na { background-color: #fef3c7; color: #92400e; border: 1px solid #fde68a; }
.ion-cl { background-color: #d1fae5; color: #065f46; border: 1px solid #a7f3d0; }
.ion-protein { background-color: #fee2e2; color: #991b1b; border: 1px solid #fca5a5; font-weight: 800; }

.membrane-divider-label {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: #334155;
  color: #ffffff;
  font-size: 0.65rem;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  z-index: 10;
}

/* Active Pump Animation Canvas / Box */
.pump-cycle-box {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
}

#pumpAnimationCanvas {
  max-width: 100%;
  height: 220px;
  display: block;
}

/* ==========================================================================
   Chapter 3: Action Potential & Excitable Membranes Styling
   ========================================================================== */
.state-indicator-box {
  background-color: var(--bg-main);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  margin-bottom: 1.25rem;
}

.state-badge-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.state-step-num {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.state-title-pill {
  font-size: 0.9rem;
  font-weight: 700;
  background-color: #eff6ff;
  border: 1px solid #bfdbfe;
  color: #1d4ed8;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
}

.state-description-text {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-top: 0.6rem;
}

.state-buttons-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.6rem;
  margin-bottom: 0.5rem;
}

.state-buttons-grid .btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  font-size: 0.85rem;
  padding: 0.6rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: #ffffff;
  color: var(--text-primary);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.state-buttons-grid .btn:hover {
  background-color: var(--bg-subtle);
  border-color: var(--primary);
}

.state-buttons-grid .btn.active {
  background-color: #eff6ff;
  border-color: var(--primary);
  color: var(--primary);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.15);
}

.btn-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background-color: var(--bg-subtle);
  font-size: 0.75rem;
  font-weight: 700;
}

.gate-status-matrix {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 0.75rem;
}

.phases-cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1rem;
}

.phase-card {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem 1rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.phase-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.phase-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.5rem;
}

.phase-letter {
  font-size: 0.75rem;
  font-weight: 700;
  background-color: #eff6ff;
  color: #2563eb;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
}

.phase-card h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
}

.phase-v-val {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 800;
  color: #0f172a;
  margin: 0.4rem 0 0.6rem;
}

.refractory-state-box {
  background-color: #fffbeb;
  border: 1px solid #fde68a;
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  margin-top: 1rem;
}

.refractory-zone-title {
  font-weight: 700;
  font-size: 0.95rem;
  color: #92400e;
  margin-bottom: 0.25rem;
}

.case-ledger-content {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.case-presentation-block,
.case-physics-block,
.case-rx-block {
  border-left: 3px solid var(--primary);
  padding-left: 1rem;
}

.case-presentation-block h4,
.case-physics-block h4,
.case-rx-block h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
}

/* Footer */
.app-footer {
  background-color: #ffffff;
  border-top: 1px solid var(--border-color);
  padding: 1.5rem 2rem;
  margin-top: auto;
  font-size: 0.825rem;
  color: var(--text-muted);
}

.footer-container {
  max-width: 1440px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-left {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.footer-right {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.25rem;
  font-family: var(--font-mono);
}

@media (max-width: 1024px) {
  .app-sidebar {
    width: 260px;
    min-width: 260px;
  }
  .main-viewport {
    max-width: calc(100vw - 260px);
    padding: 1.5rem 1.25rem 3rem;
  }

  .grid-2col,
  .sim-dashboard-layout,
  .inhibition-sandbox-layout,
  .components-grid,
  .clinical-grid,
  .term-breakdown-grid,
  .dual-inhibition-charts {
    grid-template-columns: 1fr;
  }
  
  .sim-dashboard-layout,
  .inhibition-sandbox-layout {
    display: flex;
    flex-direction: column;
  }
}

@media (max-width: 768px) {
  .app-layout-wrapper {
    flex-direction: column;
    max-width: 100vw;
    width: 100%;
    overflow-x: hidden;
  }

  .mobile-sidebar-toggle {
    display: inline-flex;
  }

  .app-sidebar {
    width: 100%;
    min-width: 100%;
    max-width: 100%;
    height: auto;
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--border-color);
  }

  .app-sidebar.mobile-collapsed .sidebar-chapters-list {
    display: none;
  }

  .header-container {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .main-viewport {
    max-width: 100vw;
    width: 100%;
    overflow-x: hidden;
    padding: 1rem 0.75rem 3rem;
  }

  .viewport-3d-wrapper,
  .three-viewport {
    max-width: 100%;
  }

  .three-viewport canvas {
    max-width: 100% !important;
  }
  
  .metrics-grid,
  .intercepts-grid,
  .delivery-metrics-grid,
  .regression-summary-box,
  .clinical-grid,
  .term-breakdown-grid,
  .phases-cards-grid,
  .gate-status-matrix,
  .state-buttons-grid {
    grid-template-columns: 1fr;
  }
  
  .full-width {
    grid-column: span 1;
  }
  
  .footer-container {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .footer-right {
    align-items: flex-start;
  }
}