/* ==========================================================================
   StatLab Interactive - Design System & Modern Light Theme
   ========================================================================== */

:root {
  /* Color Palette - Crisp Light Modern Slate & Indigo */
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-card-subtle: #f1f5f9;
  --bg-navbar: rgba(255, 255, 255, 0.85);
  --bg-control: #ffffff;
  --bg-hover: #f8fafc;
  --bg-success: #ecfdf5;
  --bg-danger: #fff1f2;
  --hero-start: #ffffff;
  --hero-title-start: #0f172a;
  --hero-title-end: #334155;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-light: #eef2ff;

  --accent-cyan: #06b6d4;
  --accent-emerald: #10b981;
  --accent-purple: #8b5cf6;
  --accent-rose: #f43f5e;
  --accent-amber: #f59e0b;

  --border-color: #e2e8f0;
  --border-color-hover: #cbd5e1;
  --focus-ring: rgba(79, 70, 229, 0.15);
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;

  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'Fira Code', monospace;
}

body.dark-mode {
  --bg-main: #0f172a;
  --bg-card: #172033;
  --bg-card-subtle: #1e293b;
  --bg-navbar: rgba(15, 23, 42, 0.88);
  --bg-control: #1e293b;
  --bg-hover: #24324a;
  --bg-success: #12362d;
  --bg-danger: #3b1d2a;
  --hero-start: #172033;
  --hero-title-start: #f8fafc;
  --hero-title-end: #a5b4fc;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --primary-light: #252a5b;
  --border-color: #334155;
  --border-color-hover: #64748b;
  --focus-ring: rgba(129, 140, 248, 0.28);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.28);
  --shadow-md: 0 8px 18px rgba(0, 0, 0, 0.28);
  --shadow-lg: 0 16px 32px rgba(0, 0, 0, 0.34);
}

/* Reset & Global Base Styles */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  padding-top: 76px; /* space for fixed navbar */
}

/* Navbar */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 76px;
  background-color: var(--bg-navbar);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
  display: flex;
  align-items: center;
}

.nav-container {
  width: 100%;
  max-width: 1600px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
  min-width: 0;
}

.brand-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent-purple) 100%);
  color: #fff;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.brand-subtitle {
  font-size: 0.75rem;
  color: var(--text-secondary);
  display: none;
  white-space: nowrap;
}

.nav-track {
  flex: 1 1 auto;
  min-width: 0;
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr) 32px;
  align-items: center;
  gap: 6px;
}

.nav-viewport {
  min-width: 0;
  overflow-x: auto;
  scroll-behavior: smooth;
  scrollbar-width: none;
}

.nav-viewport::-webkit-scrollbar { display: none; }

.nav-menu {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: calc((100% - 18px) / 4);
  gap: 6px;
  background-color: var(--bg-card-subtle);
  padding: 4px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  width: 100%;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 8px;
  justify-content: center;
  min-height: 56px;
  padding: 8px 10px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s ease;
}

.nav-scroll-btn {
  width: 32px;
  height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  background: var(--bg-control);
  cursor: pointer;
  transition: all 0.2s ease;
}

.nav-scroll-btn:hover:not(:disabled) { color: var(--primary); border-color: var(--primary); background: var(--primary-light); }
.nav-scroll-btn:disabled { opacity: 0.4; cursor: not-allowed; }
.nav-scroll-btn i { width: 17px; height: 17px; }

.nav-link:hover {
  color: var(--text-primary);
  background-color: var(--bg-hover);
}

.nav-link.active {
  color: var(--primary);
  background-color: var(--bg-control);
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

.nav-link i {
  width: 16px;
  height: 16px;
}

/* Nav Controls */
.nav-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.theme-btn, .lang-btn, .phonetic-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 0.2s ease;
}

.lang-btn {
  color: var(--primary);
  background-color: var(--primary-light);
  border: 1px solid rgba(79, 70, 229, 0.2);
}

.lang-btn:hover {
  background-color: #e0e7ff;
  transform: translateY(-1px);
}

.theme-btn {
  color: var(--text-secondary);
  background-color: var(--bg-control);
  border: 1px solid var(--border-color);
}

.theme-btn:hover {
  color: var(--primary);
  background-color: var(--primary-light);
  transform: translateY(-1px);
}

.phonetic-btn {
  color: var(--text-secondary);
  background-color: #ffffff;
  border: 1px solid var(--border-color);
}

.phonetic-btn.active {
  color: var(--accent-purple);
  background-color: #f3e8ff;
  border-color: #d8b4fe;
}

.phonetic-btn:hover {
  transform: translateY(-1px);
}

.theme-btn i, .lang-btn i, .phonetic-btn i {
  width: 16px;
  height: 16px;
}

/* IPA Phonetic Badges & Audio Buttons */
.ipa-wrapper {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin: 0 4px;
  vertical-align: middle;
}

.ipa-tag {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 500;
  color: #7e22ce;
  background-color: #f3e8ff;
  border: 1px solid #e9d5ff;
  padding: 2px 8px;
  border-radius: 999px;
  display: inline-block;
  transition: opacity 0.2s ease, transform 0.2s ease;
}

body:not(.show-ipa) .ipa-tag {
  display: none !important;
}

.audio-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  border: 1px solid var(--border-color);
  background-color: var(--bg-control);
  color: var(--primary);
  cursor: pointer;
  transition: all 0.15s ease;
  vertical-align: middle;
  padding: 0;
}

.audio-btn:hover {
  background-color: var(--primary-light);
  border-color: var(--primary);
  transform: scale(1.15);
}

.audio-btn i {
  width: 12px;
  height: 12px;
}

.audio-btn.playing {
  animation: pulse 0.5s infinite alternate;
  background-color: var(--primary);
  color: #ffffff;
}

@keyframes pulse {
  from { transform: scale(1); }
  to { transform: scale(1.2); }
}

/* Hero Banner */
.hero-banner {
  background: linear-gradient(180deg, var(--hero-start) 0%, var(--bg-main) 100%);
  border-bottom: 1px solid var(--border-color);
  padding: 36px 0 28px 0;
}

.hero-content {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.hero-text-block h1 {
  font-size: 2.1rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin-bottom: 8px;
  background: linear-gradient(135deg, var(--hero-title-start) 0%, var(--hero-title-end) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-text-block p {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 720px;
}

.hero-stats {
  display: flex;
  gap: 16px;
}

.stat-card {
  background: var(--bg-control);
  border: 1px solid var(--border-color);
  padding: 12px 20px;
  border-radius: var(--radius-md);
  text-align: center;
  box-shadow: var(--shadow-sm);
  min-width: 110px;
}

.stat-num {
  display: block;
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary);
}

.stat-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Main Container & Section Layouts */
.main-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 32px 24px 64px 24px;
}

.tab-panel {
  display: none;
  animation: fadeIn 0.3s ease;
}

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

/* Probability & Distribution Lab */
.probability-intro-grid {
  margin-bottom: 0;
}

.probability-card-copy {
  color: var(--text-secondary);
  min-height: 52px;
}

.formula-note {
  margin-top: 12px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  overflow-x: auto;
}

.probability-widget-body {
  align-items: stretch;
}

.probability-widget-body > .chart-panel {
  height: 380px;
  overflow: visible;
}

.canvas-wrapper.probability-canvas {
  height: 100%;
  min-height: 0;
}

.probability-result-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.probability-result-grid > div {
  padding: 10px;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
}

.probability-result-grid span,
.probability-result-grid strong {
  display: block;
}

.probability-result-grid span {
  color: var(--text-muted);
  font-size: 0.72rem;
}

.probability-result-grid strong {
  color: var(--primary);
  font-family: var(--font-mono);
  margin-top: 3px;
  font-size: 0.88rem;
}

.bayes-visual {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: linear-gradient(145deg, var(--bg-card-subtle), var(--bg-card));
  padding: 24px;
  min-width: 0;
}

.bayes-tree {
  display: grid;
  grid-template-columns: 1fr 1.35fr 1.35fr;
  align-items: center;
  gap: 14px;
  min-height: 190px;
}

.bayes-node {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 14px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  text-align: center;
}

.bayes-node strong { color: var(--text-primary); }
.bayes-node span, .bayes-branch > span { color: var(--text-secondary); font-size: 0.8rem; }
.bayes-node.prior { border-color: rgba(79, 70, 229, 0.35); }
.bayes-node.success { border-color: rgba(16, 185, 129, 0.5); background: var(--bg-success); }
.bayes-node.warning { border-color: rgba(245, 158, 11, 0.5); background: color-mix(in srgb, var(--bg-card) 80%, #f59e0b 20%); }

.bayes-branch {
  display: flex;
  flex-direction: column;
  gap: 8px;
  position: relative;
}

.bayes-branch::before {
  content: '';
  height: 1px;
  background: var(--border-color-hover);
  width: 16px;
  position: absolute;
  left: -22px;
  top: 50%;
}

.bayes-explanation {
  margin-top: 24px;
  padding: 16px;
  border-left: 3px solid var(--primary);
  background: var(--primary-light);
  color: var(--text-secondary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.bayes-explanation span { color: var(--primary); font: 700 1.25rem var(--font-mono); margin-left: 8px; }
.bayes-explanation p { font-size: 0.82rem; margin-top: 6px; }
.dependency-note { color: var(--text-secondary); padding: 20px; }

body.dark-mode .controls-panel { background-color: var(--bg-card-subtle); }
body.dark-mode .phonetic-btn { background-color: var(--bg-control); }

@media (max-width: 720px) {
  .probability-result-grid { grid-template-columns: 1fr; }
  .bayes-tree { grid-template-columns: 1fr; }
  .bayes-branch::before { display: none; }
  .probability-widget-body > .chart-panel { height: 300px; }
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.section-header {
  margin-bottom: 28px;
}

.badge {
  display: inline-block;
  padding: 4px 12px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--primary);
  background-color: var(--primary-light);
  border-radius: 999px;
  margin-bottom: 8px;
}

.section-header h2 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Cards & Grid Layouts */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 20px;
  margin-bottom: 28px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}

.card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--border-color-hover);
}

.card-wide {
  grid-column: 1 / -1;
}

.card-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.card-icon {
  color: var(--primary);
  width: 24px;
  height: 24px;
}

.card-header h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-primary);
}

.concept-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.concept-list li {
  font-size: 0.925rem;
  color: var(--text-secondary);
}

.concept-list strong {
  color: var(--text-primary);
}

.math-expr {
  margin-top: 6px;
  padding: 6px 12px;
  background-color: var(--bg-card-subtle);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  overflow-x: auto;
}

/* Interactive Widgets Container */
.interactive-widget {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  margin-top: 24px;
}

.widget-header {
  padding: 20px 24px;
  background-color: var(--bg-card-subtle);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.widget-header p {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.widget-badge, .decision-badge {
  padding: 6px 14px;
  font-size: 0.85rem;
  font-weight: 700;
  border-radius: 999px;
  background-color: #e0f2fe;
  color: #0369a1;
  border: 1px solid #bae6fd;
}

.decision-badge.reject {
  background-color: #ffe4e6;
  color: #e11d48;
  border-color: #fecdd3;
}

.decision-badge.accept {
  background-color: #dcfce7;
  color: #15803d;
  border-color: #bbf7d0;
}

.widget-body {
  padding: 24px;
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 24px;
}

@media (max-width: 960px) {
  .widget-body {
    grid-template-columns: 1fr;
  }
}

.controls-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
  background-color: #f8fafc;
  padding: 20px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.control-group label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
}

.slider-wrapper {
  display: flex;
  align-items: center;
  gap: 8px;
}

.slider-val-tag {
  font-size: 0.75rem;
  color: var(--text-muted);
}

input[type="range"] {
  width: 100%;
  accent-color: var(--primary);
  cursor: pointer;
}

.value-display {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  text-align: right;
}

.select-input {
  width: 100%;
  padding: 10px 14px;
  font-size: 0.875rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background-color: var(--bg-control);
  color: var(--text-primary);
  outline: none;
  font-family: var(--font-sans);
}

.select-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--focus-ring);
}

/* Stats summary box inside controls */
.stats-summary-box, .stats-card {
  background-color: var(--bg-control);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.stat-indicator {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.875rem;
}

.stat-indicator .ind-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  margin-right: 6px;
  display: inline-block;
}

.mean-ind .ind-dot { background-color: var(--primary); }
.median-ind .ind-dot { background-color: var(--accent-emerald); }
.mode-ind .ind-dot { background-color: var(--accent-purple); }

.stat-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

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

.rule-callout {
  display: flex;
  align-items: center;
  gap: 10px;
  background-color: #eff6ff;
  border: 1px solid #bfdbfe;
  color: #1e40af;
  padding: 12px;
  border-radius: var(--radius-sm);
  font-size: 0.825rem;
  line-height: 1.4;
}

.rule-callout i {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

/* Chart Panels & Canvas Wrappers Fix for Chart.js Resize Loop */
.chart-panel {
  position: relative;
  height: 320px;
  width: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  overflow: hidden;
}

.canvas-wrapper {
  position: relative;
  height: 260px;
  width: 100%;
  overflow: hidden;
}

.dual-chart-panel {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

@media (max-width: 900px) {
  .dual-chart-panel {
    grid-template-columns: 1fr;
  }
}

.sub-chart {
  background: var(--bg-control);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 16px;
  position: relative;
  height: 320px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sub-chart h4 {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 12px;
  flex-shrink: 0;
}

/* Sub-tab Navigation (Module 2) */
.sub-tab-bar {
  display: flex;
  gap: 12px;
  margin-bottom: 20px;
  border-bottom: 2px solid var(--border-color);
  padding-bottom: 2px;
}

.sub-tab-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: transparent;
  border: none;
  border-bottom: 3px solid transparent;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-bottom: -4px;
}

.sub-tab-btn:hover {
  color: var(--text-primary);
}

.sub-tab-btn.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.subtab-content {
  display: none;
}

.subtab-content.active {
  display: block;
  animation: fadeIn 0.25s ease;
}

.info-card {
  background-color: var(--bg-control);
  border-left: 4px solid var(--primary);
  border-top: 1px solid var(--border-color);
  border-right: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  margin-bottom: 20px;
}

.info-card h3 {
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.info-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff;
  box-shadow: 0 2px 4px rgba(79, 70, 229, 0.2);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  box-shadow: 0 4px 8px rgba(79, 70, 229, 0.3);
}

.btn-secondary {
  background-color: var(--bg-control);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--bg-card-subtle);
}

.btn-secondary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-full {
  width: 100%;
}

.btn-lg {
  padding: 12px 28px;
  font-size: 1rem;
}

.controls-row {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Test Selector Tabs (Module 3) */
.test-tabs-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin-bottom: 20px;
}

.test-tab-btn {
  padding: 14px 16px;
  background-color: var(--bg-control);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 0.925rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
  text-align: center;
}

.test-tab-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.test-tab-btn.active {
  background-color: var(--primary-light);
  border-color: var(--primary);
  color: var(--primary);
  font-weight: 700;
}

/* Canvas & Legend */
.canvas-panel {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  height: auto;
  min-height: 410px;
  overflow: visible;
  padding: 16px 0 12px;
}

#hypothesisCanvas {
  width: 100%;
  max-width: 700px;
  height: 340px;
  background-color: var(--bg-main);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.canvas-legend {
  display: flex;
  gap: 18px;
  margin-top: 12px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.color-box {
  width: 12px;
  height: 12px;
  border-radius: 3px;
}

.area-accept { background-color: rgba(99, 102, 241, 0.2); border: 1px solid #6366f1; }
.area-reject { background-color: rgba(244, 63, 94, 0.4); border: 1px solid #f43f5e; }
.area-pvalue { background-color: rgba(16, 185, 129, 0.4); border: 1px solid #10b981; }

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

.control-note {
  margin: 8px 0 0;
  color: var(--text-secondary);
  font-size: 0.78rem;
  line-height: 1.45;
}

.result-summary {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 18px;
}

.result-metric {
  padding: 12px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-control);
}

.result-metric span, .decision-step small {
  display: block;
  color: var(--text-secondary);
  font-size: 0.72rem;
  font-weight: 600;
  line-height: 1.35;
}

.result-metric strong {
  display: block;
  margin-top: 5px;
  color: var(--text-primary);
  font-size: 0.95rem;
}

.decision-explanation {
  margin: 14px 0 0;
  color: var(--text-secondary);
  font-size: 0.88rem;
  line-height: 1.5;
}

.decision-path {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  padding: 18px 22px 22px;
  border-top: 1px solid var(--border-color);
  background: linear-gradient(180deg, var(--bg-control), var(--bg-card-subtle));
}

.decision-step {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  min-width: 0;
  padding: 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-control);
}

.decision-step strong {
  display: block;
  margin-top: 3px;
  color: var(--text-primary);
  font-size: 0.78rem;
  line-height: 1.4;
  overflow-wrap: anywhere;
}

.step-number {
  display: inline-grid;
  place-items: center;
  flex: 0 0 22px;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary-light);
  color: var(--primary);
  font-size: 0.74rem;
  font-weight: 700;
}

.decision-step.final.accept { border-color: #6ee7b7; background: #ecfdf5; }
.decision-step.final.reject { border-color: #fda4af; background: #fff1f2; }
.decision-step.final.accept .step-number { background: #d1fae5; color: #047857; }
.decision-step.final.reject .step-number { background: #ffe4e6; color: #be123c; }
.data-table tr.active-test-row { background: var(--primary-light); box-shadow: inset 3px 0 0 var(--primary); }

@media (max-width: 760px) {
  body { padding-top: 70px; }
  .navbar { height: 70px; }
  .nav-container { padding: 0 10px; gap: 6px; }
  .brand-text { display: none; }
  .nav-track { grid-template-columns: 28px minmax(0, 1fr) 28px; gap: 3px; }
  .nav-menu { grid-auto-columns: calc((100% - 6px) / 2); gap: 6px; }
  .nav-link { min-height: 52px; padding: 6px; font-size: 0.78rem; gap: 5px; }
  .nav-link i { width: 14px; height: 14px; }
  .nav-scroll-btn { width: 28px; height: 34px; }
  .nav-controls { gap: 4px; }
  .nav-controls span { display: none; }
  .theme-btn, .lang-btn, .phonetic-btn { width: 34px; height: 34px; padding: 0; justify-content: center; }
  .result-summary, .decision-path { grid-template-columns: 1fr; }
  .decision-path { padding: 14px; }
  #hypothesisCanvas { height: 280px; }
  .canvas-panel { min-height: 350px; padding-top: 12px; }
  .canvas-legend { flex-wrap: wrap; justify-content: center; }
}

@media (min-width: 1500px) {
  .brand-subtitle { display: block; }
}

/* Data Table */
.data-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 12px;
  font-size: 0.9rem;
}

.data-table th, .data-table td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

.data-table th {
  background-color: var(--bg-card-subtle);
  font-weight: 600;
  color: var(--text-primary);
}

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

/* Quiz Section (Module 4) */
.quiz-container {
  max-width: 800px;
  margin: 0 auto;
}

.quiz-header {
  margin-bottom: 20px;
}

.quiz-progress-bar-wrap {
  width: 100%;
  height: 8px;
  background-color: var(--border-color);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 12px;
}

.quiz-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary) 0%, var(--accent-cyan) 100%);
  transition: width 0.3s ease;
}

.quiz-status {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.score-badge {
  background-color: var(--primary-light);
  color: var(--primary);
  padding: 4px 12px;
  border-radius: 999px;
}

.quiz-card {
  background: var(--bg-control);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-md);
}

.quiz-category-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-purple);
  background-color: #f3e8ff;
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}

.quiz-question-text {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 24px;
}

.quiz-options-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 24px;
}

.option-btn {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 14px 20px;
  background-color: var(--bg-control);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
  transition: all 0.2s ease;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--primary);
  background-color: var(--primary-light);
}

.option-marker {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background-color: var(--bg-card-subtle);
  color: var(--text-secondary);
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 0.85rem;
}

.option-btn.selected {
  border-color: var(--primary);
  background-color: var(--primary-light);
}

.option-btn.correct {
  border-color: var(--accent-emerald);
  background-color: #dcfce7;
  color: #166534;
}

.option-btn.correct .option-marker {
  background-color: var(--accent-emerald);
  color: #ffffff;
}

.option-btn.wrong {
  border-color: var(--accent-rose);
  background-color: #ffe4e6;
  color: #9f1239;
}

.option-btn.wrong .option-marker {
  background-color: var(--accent-rose);
  color: #ffffff;
}

.quiz-feedback-box {
  display: flex;
  gap: 14px;
  padding: 16px;
  border-radius: var(--radius-md);
  margin-bottom: 24px;
}

.quiz-feedback-box.correct {
  background-color: #f0fdf4;
  border: 1px solid #bbf7d0;
  color: #166534;
}

.quiz-feedback-box.wrong {
  background-color: #fff1f2;
  border: 1px solid #fecdd3;
  color: #9f1239;
}

.quiz-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.quiz-result-card {
  background: var(--bg-control);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 48px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}

.result-icon {
  width: 72px;
  height: 72px;
  background: linear-gradient(135deg, var(--accent-amber) 0%, #f59e0b 100%);
  color: #ffffff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px auto;
  box-shadow: 0 10px 20px rgba(245, 158, 11, 0.3);
}

.result-score-text {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin: 12px 0;
}

.result-score-text strong {
  color: var(--primary);
  font-size: 1.75rem;
}

/* Cheat Sheet Section (Module 5) */
.cheatsheet-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 20px;
}

.cheat-card {
  background: var(--bg-control);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.cheat-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  border-bottom: 2px solid var(--primary-light);
  padding-bottom: 8px;
}

.cheat-item {
  margin-bottom: 14px;
}

.cheat-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.highlight-card {
  background: #faf5ff;
  border-color: #e9d5ff;
}

.highlight-card h3 {
  color: #7e22ce;
  border-bottom-color: #f3e8ff;
}

.trap-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
  font-size: 0.875rem;
  color: #581c87;
}

/* Footer */
.footer {
  background-color: var(--bg-control);
  border-top: 1px solid var(--border-color);
  padding: 24px 0;
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.mt-4 { margin-top: 24px; }
.mb-3 { margin-bottom: 12px; }
.mb-4 { margin-bottom: 24px; }

/* ==========================================================================
   Floating Watermark Badge (Option 3)
   ========================================================================== */
.floating-watermark-badge {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 999;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(79, 70, 229, 0.25);
  border-radius: 30px;
  color: #0f172a;
  font-family: var(--font-mono);
  font-size: 0.825rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  box-shadow: 0 8px 24px rgba(79, 70, 229, 0.15), 0 2px 8px rgba(0, 0, 0, 0.05);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  user-select: none;
  cursor: default;
}

.floating-watermark-badge:hover {
  transform: translateY(-3px) scale(1.03);
  border-color: var(--primary);
  box-shadow: 0 12px 30px rgba(79, 70, 229, 0.3);
}

.badge-pulse {
  width: 8px;
  height: 8px;
  background-color: var(--primary);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--primary);
  animation: badgePulse 2s infinite ease-in-out;
}

@keyframes badgePulse {
  0%, 100% { transform: scale(1); opacity: 0.8; }
  50% { transform: scale(1.35); opacity: 1; box-shadow: 0 0 12px var(--primary); }
}

.feedback-widget {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 999;
}

.feedback-widget .floating-watermark-badge {
  position: relative;
  right: auto;
  bottom: auto;
  z-index: auto;
  appearance: none;
  cursor: pointer;
  font: inherit;
}

.feedback-widget .floating-watermark-badge:focus-visible,
.feedback-close:focus-visible,
.feedback-contact-link:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 3px;
}

.feedback-panel {
  position: absolute;
  right: 0;
  bottom: calc(100% + 12px);
  width: min(300px, calc(100vw - 32px));
  padding: 16px;
  border: 1px solid rgba(79, 70, 229, 0.3);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  box-shadow: var(--shadow-lg);
  animation: feedbackPanelEnter 180ms ease-out;
}

.feedback-panel[hidden] { display: none; }

.feedback-panel h2 {
  margin: 0 28px 10px 0;
  color: var(--text-primary);
  font-size: 1rem;
}

.feedback-close {
  position: absolute;
  top: 10px;
  right: 10px;
  display: inline-grid;
  width: 30px;
  height: 30px;
  place-items: center;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
}

.feedback-close:hover { background: var(--bg-hover); color: var(--text-primary); }
.feedback-close svg { width: 16px; height: 16px; }

.feedback-contact-link {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  margin: 0 -8px;
  padding: 10px 8px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.75rem;
  text-decoration: none;
  transition: background-color 160ms ease, color 160ms ease;
}

.feedback-contact-link + .feedback-contact-link { border-top: 1px solid var(--border-color); }
.feedback-contact-link:hover { background: var(--bg-hover); }
.feedback-contact-link:hover strong { color: var(--primary); }
.feedback-contact-link > i,
.feedback-contact-link > svg {
  flex: 0 0 18px;
  width: 18px;
  height: 18px;
  margin-top: 2px;
  color: var(--primary);
}

.feedback-contact-content {
  display: flex;
  flex: 1 1 auto;
  flex-direction: column;
  min-width: 0;
  gap: 2px;
}

.feedback-contact-content > span { color: var(--text-secondary); }
.feedback-contact-link strong {
  min-width: 0;
  overflow-wrap: anywhere;
  color: var(--text-primary);
  font-size: 0.8rem;
  font-weight: 600;
  line-height: 1.35;
}

@keyframes feedbackPanelEnter {
  from { opacity: 0; transform: translateY(8px) scale(0.98); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

@media (max-width: 480px) {
  .feedback-widget { right: 12px; bottom: 16px; }
  .feedback-panel { width: min(300px, calc(100vw - 24px)); }
}

@media (prefers-reduced-motion: reduce) {
  .feedback-panel { animation: none; transition: none; }
}

/* Dark-theme refinements for semantic states that use data-specific colors. */
body.dark-mode .phonetic-btn { background-color: var(--bg-control); }
body.dark-mode .phonetic-btn.active { background-color: #33214f; border-color: #7c3aed; color: #d8b4fe; }
body.dark-mode .ipa-tag { background-color: #33214f; border-color: #6d3ca1; color: #e9d5ff; }
body.dark-mode .widget-badge { background-color: #123548; border-color: #155e75; color: #67e8f9; }
body.dark-mode .decision-badge.reject { background-color: #451d2a; border-color: #9f1239; color: #fda4af; }
body.dark-mode .decision-badge.accept { background-color: #163d32; border-color: #047857; color: #6ee7b7; }
body.dark-mode .controls-panel { background-color: var(--bg-card-subtle); }
body.dark-mode .rule-callout { background-color: #172b4d; border-color: #315a9b; color: #bfdbfe; }
body.dark-mode .decision-step.final.accept { border-color: #047857; background: var(--bg-success); }
body.dark-mode .decision-step.final.reject { border-color: #9f1239; background: var(--bg-danger); }
body.dark-mode .decision-step.final.accept .step-number { background: #164e3c; color: #a7f3d0; }
body.dark-mode .decision-step.final.reject .step-number { background: #4c1d2b; color: #fecdd3; }
body.dark-mode .option-btn.correct { background-color: #163d32; color: #bbf7d0; }
body.dark-mode .option-btn.wrong { background-color: #451d2a; color: #fecdd3; }
body.dark-mode .quiz-feedback-box.correct { background-color: #163d32; border-color: #047857; color: #bbf7d0; }
body.dark-mode .quiz-feedback-box.wrong { background-color: #451d2a; border-color: #9f1239; color: #fecdd3; }
body.dark-mode .highlight-card { background: #2d1b45; border-color: #6d3ca1; }
body.dark-mode .highlight-card h3 { color: #e9d5ff; border-bottom-color: #6d3ca1; }
body.dark-mode .trap-list { color: #e9d5ff; }
body.dark-mode .floating-watermark-badge { background: rgba(30, 41, 59, 0.9); color: var(--text-primary); }