/* ============================================
   BioLab Interactivo v2.0 - Styles
   ============================================ */

:root {
  --primary: #7e57c2;
  --primary-dark: #5e35b1;
  --primary-light: #b39ddb;
  --secondary: #ff7043;
  --accent-green: #66bb6a;
  --accent-blue: #42a5f5;
  --accent-red: #ef5350;
  --accent-purple: #ab47bc;
  --accent-orange: #ffa726;
  --bg-gradient-start: #f3e5f5;
  --bg-gradient-end: #e8eaf6;
  --card-bg: #ffffff;
  --text-primary: #2c3e50;
  --text-secondary: #546e7a;
  --text-muted: #90a4ae;
  --border-radius: 20px;
  --border-radius-sm: 12px;
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
  --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
  --shadow-lg: 0 16px 48px rgba(0,0,0,0.12);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: 'Nunito', 'Segoe UI', system-ui, sans-serif;
  background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
  min-height: 100vh;
  color: var(--text-primary);
  line-height: 1.6;
}

/* ============================================
   App Container
   ============================================ */
.app-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ============================================
   Header
   ============================================ */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--card-bg);
  padding: 16px 28px;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  margin-bottom: 20px;
  flex-wrap: wrap;
  gap: 16px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 14px;
}

.logo-icon {
  font-size: 2.8rem;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}

.logo-text h1 {
  font-size: 1.5rem;
  color: var(--primary-dark);
  font-weight: 800;
  margin: 0;
  line-height: 1.2;
}

.logo-text p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin: 0;
}

.progress-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  background: #f5f5f5;
  padding: 8px 16px;
  border-radius: 30px;
  min-width: 200px;
}

.progress-fill {
  width: 0%;
  height: 8px;
  background: linear-gradient(90deg, var(--primary), var(--accent-purple));
  border-radius: 4px;
  transition: width 0.5s ease;
}

.progress-text {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 600;
  white-space: nowrap;
}

/* ============================================
   Tab Navigation
   ============================================ */
.tab-nav {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.tab-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border: none;
  border-radius: var(--border-radius-sm);
  background: var(--card-bg);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

.tab-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: var(--primary);
}

.tab-btn.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  box-shadow: 0 4px 16px rgba(126, 87, 194, 0.35);
}

.tab-icon {
  font-size: 1.2rem;
}

/* ============================================
   Main Content & Mode Sections
   ============================================ */
.main-content {
  flex: 1;
}

.mode-section {
  display: none;
  animation: fadeIn 0.4s ease;
}

.mode-section.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ============================================
   EXPLORER MODE
   ============================================ */
.explorer-layout {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 24px;
  align-items: start;
}

.cell-canvas-container {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 20px;
  box-shadow: var(--shadow-md);
}

.cell-type-toggle {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
  justify-content: center;
}

.type-btn {
  padding: 8px 20px;
  border: 2px solid var(--primary-light);
  border-radius: 20px;
  background: white;
  color: var(--primary);
  font-family: inherit;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
}

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

.type-btn.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  border-color: var(--primary);
}

.cell-svg {
  width: 100%;
  max-width: 500px;
  display: block;
  margin: 0 auto;
  cursor: pointer;
}

.organelle-group {
  cursor: pointer;
  transition: opacity 0.2s;
}

.organelle-group:hover {
  opacity: 0.85;
}

.organelle-group:hover .organelle-label {
  font-weight: 800;
  text-shadow: 0 0 8px rgba(255,255,255,0.8);
}

.organelle-label {
  font-family: 'Nunito', sans-serif;
  font-size: 13px;
  font-weight: 700;
  pointer-events: none;
  text-shadow: 0 1px 3px rgba(255,255,255,0.9), 0 0 6px rgba(255,255,255,0.6);
  transition: all 0.2s;
}

.canvas-hint {
  text-align: center;
  margin-top: 12px;
  color: var(--text-muted);
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.hint-icon {
  font-size: 1.2rem;
}

/* Info Panel */
.info-panel {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 28px;
  box-shadow: var(--shadow-md);
  border-left: 5px solid var(--primary);
  min-height: 500px;
  transition: border-left-color 0.3s;
}

.info-welcome {
  text-align: center;
}

.welcome-icon {
  font-size: 4rem;
  margin-bottom: 12px;
  display: block;
}

.welcome-title {
  color: var(--primary-dark);
  font-size: 1.4rem;
  margin-bottom: 8px;
}

.welcome-desc {
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.feature-list {
  list-style: none;
  text-align: left;
  max-width: 280px;
  margin: 0 auto 24px;
}

.feature-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 0;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.feature-icon {
  font-size: 1.3rem;
}

.cell-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: #ede7f6;
  padding: 12px 20px;
  border-radius: var(--border-radius-sm);
  margin-top: 8px;
}

.badge-icon {
  font-size: 1.5rem;
}

.badge-text {
  color: var(--primary-dark);
  font-weight: 700;
  font-size: 0.95rem;
}

/* Organelle Info Content */
.organelle-info {
  animation: slideIn 0.3s ease;
}

@keyframes slideIn {
  from { opacity: 0; transform: translateX(10px); }
  to { opacity: 1; transform: translateX(0); }
}

.info-title {
  font-size: 1.5rem;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.info-section {
  margin-bottom: 16px;
}

.info-section h4 {
  color: var(--text-primary);
  font-size: 1rem;
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.info-section p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
}

.info-fact {
  background: linear-gradient(135deg, #fff8e1, #ffecb3);
  padding: 14px;
  border-radius: var(--border-radius-sm);
  margin: 16px 0;
  border-left: 4px solid var(--accent-orange);
}

.info-fact p {
  color: #5d4037;
  font-size: 0.95rem;
  margin: 0;
}

.memory-card {
  background: linear-gradient(135deg, #e8eaf6, #c5cae9);
  padding: 14px;
  border-radius: var(--border-radius-sm);
  margin-top: 16px;
}

.memory-card strong {
  color: var(--primary-dark);
}

.memory-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin: 4px 0 0;
  font-style: italic;
}

/* ============================================
   QUIZ MODE
   ============================================ */
.quiz-container {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 28px;
  box-shadow: var(--shadow-md);
  max-width: 800px;
  margin: 0 auto;
}

.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 2px solid #f0f0f0;
  flex-wrap: wrap;
  gap: 12px;
}

.quiz-score, .quiz-streak, .quiz-progress {
  text-align: center;
}

.score-label, .streak-label, .progress-label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 700;
}

.score-value {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--primary);
}

.streak-value {
  font-size: 1.2rem;
  font-weight: 700;
}

.progress-value {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-secondary);
}

.quiz-card {
  text-align: center;
  padding: 20px 0;
}

.quiz-question-icon {
  font-size: 3.5rem;
  margin-bottom: 16px;
}

.quiz-question {
  font-size: 1.3rem;
  color: var(--text-primary);
  margin-bottom: 28px;
  line-height: 1.5;
  min-height: 60px;
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  max-width: 520px;
  margin: 0 auto 20px;
}

.quiz-option {
  padding: 16px 20px;
  border: 2.5px solid #e0e0e0;
  border-radius: var(--border-radius-sm);
  background: white;
  cursor: pointer;
  font-family: inherit;
  font-size: 1rem;
  color: var(--text-primary);
  font-weight: 600;
  transition: var(--transition);
  text-align: left;
  display: flex;
  align-items: center;
  gap: 10px;
}

.quiz-option:hover {
  border-color: var(--primary-light);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.quiz-option.correct {
  border-color: var(--accent-green);
  background: #e8f5e9;
  color: #2e7d32;
}

.quiz-option.incorrect {
  border-color: var(--accent-red);
  background: #ffebee;
  color: #c62828;
}

.quiz-option.disabled {
  pointer-events: none;
  opacity: 0.6;
}

.quiz-option .opt-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: #f5f5f5;
  border-radius: 50%;
  font-weight: 800;
  font-size: 0.9rem;
  color: var(--text-secondary);
  flex-shrink: 0;
}

.quiz-option.correct .opt-letter {
  background: var(--accent-green);
  color: white;
}

.quiz-option.incorrect .opt-letter {
  background: var(--accent-red);
  color: white;
}

.quiz-feedback {
  min-height: 50px;
  margin: 16px 0;
  font-weight: 700;
  font-size: 1.1rem;
  padding: 12px;
  border-radius: var(--border-radius-sm);
  animation: popIn 0.3s ease;
}

.quiz-feedback.correct {
  background: #e8f5e9;
  color: #2e7d32;
}

.quiz-feedback.incorrect {
  background: #ffebee;
  color: #c62828;
}

.quiz-controls {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 20px;
}

.quiz-btn {
  padding: 12px 28px;
  border: none;
  border-radius: 30px;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
}

.quiz-btn.primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  box-shadow: 0 4px 12px rgba(126, 87, 194, 0.3);
}

.quiz-btn.primary:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(126, 87, 194, 0.4);
}

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

.quiz-btn.secondary {
  background: #f5f5f5;
  color: var(--text-secondary);
}

.quiz-btn.secondary:hover {
  background: #e0e0e0;
}

.quiz-categories {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid #eee;
}

.cat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 700;
  align-self: center;
}

.cat-btn {
  padding: 6px 14px;
  border: 1.5px solid #e0e0e0;
  border-radius: 20px;
  background: white;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.cat-btn:hover {
  border-color: var(--primary-light);
  color: var(--primary);
}

.cat-btn.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

/* Quiz Results */
.quiz-results {
  text-align: center;
  padding: 40px 20px;
}

.results-icon {
  font-size: 5rem;
  margin-bottom: 16px;
}

.results-title {
  font-size: 1.8rem;
  color: var(--primary-dark);
  margin-bottom: 12px;
}

.results-score {
  font-size: 3rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 8px;
}

.results-message {
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: 24px;
}

.results-badges {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.result-badge {
  background: linear-gradient(135deg, #fff8e1, #ffe082);
  padding: 12px 20px;
  border-radius: var(--border-radius-sm);
  font-weight: 700;
  color: #5d4037;
  font-size: 0.95rem;
}

/* ============================================
   BUILDER MODE
   ============================================ */
.builder-container {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 24px;
}

.builder-sidebar {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 24px;
  box-shadow: var(--shadow-md);
  height: fit-content;
}

.builder-title {
  font-size: 1.2rem;
  color: var(--primary-dark);
  margin-bottom: 4px;
}

.builder-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.organelle-palette {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 20px;
}

.palette-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border-radius: var(--border-radius-sm);
  background: #fafafa;
  cursor: pointer;
  transition: var(--transition);
  border: 2px solid transparent;
}

.palette-item:hover {
  background: #f0f0f0;
  border-color: var(--primary-light);
  transform: translateX(4px);
}

.palette-item.added {
  opacity: 0.5;
  pointer-events: none;
}

.palette-preview {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  flex-shrink: 0;
}

.nucleus-preview { background: linear-gradient(135deg, #7986cb, #3949ab); }
.mito-preview { background: linear-gradient(135deg, #ef5350, #c62828); border-radius: 40%; }
.ribo-preview { background: linear-gradient(135deg, #ffcc80, #f57c00); width: 28px; height: 28px; }
.rer-preview { background: linear-gradient(135deg, #ce93d8, #8e24aa); border-radius: 30%; }
.ser-preview { background: linear-gradient(135deg, #e1bee7, #ba68c8); border-radius: 30%; }
.golgi-preview { background: linear-gradient(135deg, #64b5f6, #1976d2); border-radius: 30%; }
.membrane-preview { background: linear-gradient(135deg, #ffcc80, #ff9800); border-radius: 8px; }
.cytoskeleton-preview { background: repeating-linear-gradient(45deg, #78909c, #78909c 2px, transparent 2px, transparent 6px); border-radius: 4px; }

.palette-name {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--text-primary);
}

.palette-desc {
  font-size: 0.75rem;
  color: var(--text-muted);
  display: block;
}

.builder-actions {
  display: flex;
  gap: 10px;
}

.builder-btn {
  flex: 1;
  padding: 10px;
  border: none;
  border-radius: var(--border-radius-sm);
  font-family: inherit;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.9rem;
}

.builder-btn.reset {
  background: #ffebee;
  color: #c62828;
}

.builder-btn.reset:hover {
  background: #ffcdd2;
}

.builder-btn.hint {
  background: #e3f2fd;
  color: #1565c0;
}

.builder-btn.hint:hover {
  background: #bbdefb;
}

.builder-canvas-wrapper {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 24px;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.builder-canvas {
  width: 100%;
  max-width: 500px;
  height: 500px;
  border: 3px dashed #ce93d8;
  border-radius: 50%;
  background: linear-gradient(135deg, #fce4ec, #f3e5f5);
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

.builder-canvas.complete {
  border-color: var(--accent-green);
  border-style: solid;
  background: linear-gradient(135deg, #e8f5e9, #c8e6c9);
}

.canvas-placeholder {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  color: #ce93d8;
}

.placeholder-icon {
  font-size: 3rem;
  display: block;
  margin-bottom: 8px;
}

.placeholder-text {
  font-weight: 700;
  font-size: 1.1rem;
  display: block;
}

.placeholder-sub {
  font-size: 0.85rem;
  opacity: 0.8;
  display: block;
  margin-top: 4px;
}

.builder-part {
  position: absolute;
  transition: all 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  animation: builderPop 0.5s ease;
}

@keyframes builderPop {
  0% { transform: scale(0) rotate(-10deg); opacity: 0; }
  60% { transform: scale(1.1) rotate(2deg); }
  100% { transform: scale(1) rotate(0deg); opacity: 1; }
}

.builder-status {
  margin-top: 16px;
  font-weight: 700;
  color: var(--text-secondary);
  min-height: 24px;
  text-align: center;
}

.builder-completion {
  margin-top: 12px;
  text-align: center;
}

.completion-badge {
  display: inline-block;
  background: linear-gradient(135deg, #fff8e1, #ffe082);
  padding: 12px 24px;
  border-radius: 30px;
  font-weight: 800;
  color: #5d4037;
  font-size: 1.1rem;
  animation: bounce 0.6s ease;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

/* ============================================
   COMPARE MODE
   ============================================ */
.compare-container {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  padding: 32px;
  box-shadow: var(--shadow-md);
}

.compare-title {
  text-align: center;
  color: var(--primary-dark);
  font-size: 1.6rem;
  margin-bottom: 28px;
}

.compare-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-bottom: 32px;
}

.compare-card {
  border-radius: var(--border-radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.compare-card.procariota {
  border: 2px solid #4caf50;
}

.compare-card.eucariota {
  border: 2px solid #ff9800;
}

.compare-header {
  padding: 20px;
  text-align: center;
}

.compare-card.procariota .compare-header {
  background: linear-gradient(135deg, #e8f5e9, #c8e6c9);
}

.compare-card.eucariota .compare-header {
  background: linear-gradient(135deg, #fff3e0, #ffe0b2);
}

.compare-icon {
  font-size: 2.5rem;
  display: block;
  margin-bottom: 8px;
}

.compare-header h3 {
  margin: 0 0 4px;
  font-size: 1.3rem;
}

.compare-card.procariota .compare-header h3 {
  color: #2e7d32;
}

.compare-card.eucariota .compare-header h3 {
  color: #e65100;
}

.compare-examples {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.compare-body {
  padding: 16px 20px;
}

.compare-feature {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 8px 0;
  border-bottom: 1px solid #f0f0f0;
}

.compare-feature:last-child {
  border-bottom: none;
}

.feature-check {
  font-size: 1.1rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.feature-text {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.compare-visual {
  text-align: center;
  padding-top: 24px;
  border-top: 2px solid #f0f0f0;
}

.compare-visual h4 {
  color: var(--text-primary);
  margin-bottom: 20px;
}

.visual-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
}

.visual-cell {
  text-align: center;
}

.visual-cell svg {
  border-radius: var(--border-radius-sm);
  box-shadow: var(--shadow-sm);
}

.visual-size {
  display: block;
  margin-top: 8px;
  font-weight: 700;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.visual-arrow {
  font-size: 2rem;
  color: var(--primary);
}

/* ============================================
   Modal
   ============================================ */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: white;
  border-radius: var(--border-radius);
  padding: 32px;
  max-width: 500px;
  width: 100%;
  max-height: 80vh;
  overflow-y: auto;
  position: relative;
  box-shadow: var(--shadow-lg);
  animation: modalIn 0.3s ease;
}

@keyframes modalIn {
  from { opacity: 0; transform: scale(0.9); }
  to { opacity: 1; transform: scale(1); }
}

.modal-close {
  position: absolute;
  top: 16px;
  right: 20px;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-muted);
  transition: color 0.2s;
}

.modal-close:hover {
  color: var(--text-primary);
}

.modal-content h2 {
  color: var(--primary-dark);
  margin-bottom: 16px;
}

.modal-content h3 {
  color: var(--text-primary);
  margin: 20px 0 10px;
  font-size: 1.1rem;
}

.modal-content ul {
  padding-left: 20px;
  color: var(--text-secondary);
}

.modal-content ul li {
  margin-bottom: 6px;
}

.modal-footer {
  margin-top: 24px;
  padding-top: 16px;
  border-top: 1px solid #eee;
  color: var(--text-muted);
  font-size: 0.9rem;
  text-align: center;
}

/* ============================================
   Footer
   ============================================ */
.app-footer {
  text-align: center;
  padding: 24px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer-links {
  margin-top: 8px;
}

.footer-links a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
  transition: color 0.2s;
}

.footer-links a:hover {
  color: var(--primary-dark);
}

.sep {
  margin: 0 8px;
  color: var(--text-muted);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 900px) {
  .explorer-layout {
    grid-template-columns: 1fr;
  }

  .builder-container {
    grid-template-columns: 1fr;
  }

  .compare-grid {
    grid-template-columns: 1fr;
  }

  .quiz-options {
    grid-template-columns: 1fr;
  }

  .app-header {
    flex-direction: column;
    text-align: center;
  }

  .tab-nav {
    justify-content: center;
  }

  .tab-btn {
    padding: 10px 16px;
    font-size: 0.85rem;
  }

  .tab-label {
    display: none;
  }
}

@media (max-width: 500px) {
  .app-container {
    padding: 12px;
  }

  .cell-svg {
    max-width: 100%;
  }

  .builder-canvas {
    height: 350px;
  }

  .quiz-header {
    flex-direction: column;
    gap: 8px;
  }
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: #f1f1f1;
  border-radius: 4px;
}

::-webkit-scrollbar-thumb {
  background: var(--primary-light);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--primary);
}

/* ============================================
   BIOLOGY TOOLTIPS — Dictionary definitions
   ============================================ */

.bio-term {
  position: relative;
  cursor: help;
  border-bottom: 2px dotted currentColor;
  transition: all 0.2s ease;
}

.bio-term:hover {
  background: rgba(126, 87, 194, 0.15);
  border-radius: 4px;
  padding: 0 4px;
  margin: 0 -4px;
}

.bio-term::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) scale(0.95);
  background: linear-gradient(135deg, #4a148c, #7e57c2);
  color: white;
  padding: 10px 14px;
  border-radius: 12px;
  font-size: 0.85rem;
  font-weight: 400;
  line-height: 1.5;
  width: 260px;
  max-width: 300px;
  text-align: center;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 100;
  box-shadow: 0 8px 24px rgba(74, 20, 140, 0.3);
  pointer-events: none;
}

.bio-term::before {
  content: '';
  position: absolute;
  bottom: calc(100% + 2px);
  left: 50%;
  transform: translateX(-50%) scale(0);
  border: 6px solid transparent;
  border-top-color: #4a148c;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 100;
}

.bio-term:hover::after {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) scale(1);
}

.bio-term:hover::before {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) scale(1);
}

@media (max-width: 500px) {
  .bio-term::after {
    width: 200px;
    font-size: 0.8rem;
    padding: 8px 12px;
  }
}