/* ========== Lesson Content Specific Styles ========== */

/* Welcome page */
.welcome-page {
  max-width: 700px;
  margin: 40px auto;
  text-align: center;
}

.welcome-page h1 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.welcome-page .subtitle {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.welcome-page .feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin: 32px 0;
}

.welcome-page .feature-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 20px;
  text-align: left;
}

.welcome-page .feature-card h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--accent);
}

.welcome-page .feature-card p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
}

.welcome-page .start-btn {
  display: inline-block;
  padding: 14px 36px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: var(--radius);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: all 0.2s;
  margin-top: 16px;
}

.welcome-page .start-btn:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(83, 74, 183, 0.3);
}

/* Matrix display */
.matrix-display {
  display: inline-flex;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 16px;
  margin: 8px 0;
}

.matrix-display::before,
.matrix-display::after {
  content: '';
  width: 8px;
  align-self: stretch;
  border: 2px solid var(--text-primary);
}

.matrix-display::before {
  border-right: none;
  margin-right: 8px;
}

.matrix-display::after {
  border-left: none;
  margin-left: 8px;
}

.matrix-display table {
  border-collapse: collapse;
}

.matrix-display td {
  padding: 4px 12px;
  text-align: center;
  min-width: 40px;
}

/* Editable matrix */
.matrix-input {
  display: inline-block;
  margin: 8px 0;
}

.matrix-input table {
  border-collapse: collapse;
}

.matrix-input td {
  padding: 2px;
}

.matrix-input input {
  width: 50px;
  height: 36px;
  text-align: center;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--text-primary);
  background: white;
}

.matrix-input input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-light);
}

/* Heatmap & matrix equation panels (reference: seaborn heatmap layout) */
.heatmap-legend {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 8px 0 4px;
  font-size: 12px;
  color: var(--text-secondary);
}

.heatmap-legend-bar {
  flex: 1;
  max-width: 200px;
  height: 12px;
  border-radius: 3px;
  border: 1px solid var(--border-color);
  background: linear-gradient(to right, rgb(49,54,149), rgb(255,255,191), rgb(165,0,38));
}

.matrix-equation-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin: 12px 0;
}

.matrix-equation-op {
  font-size: 22px;
  font-weight: 600;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.slice-preview-row {
  display: flex;
  gap: 16px;
  justify-content: center;
  align-items: flex-start;
  flex-wrap: wrap;
  margin-top: 12px;
}

.slice-preview-item {
  text-align: center;
}

.slice-preview-item .slice-label {
  font-size: 12px;
  color: var(--text-secondary);
  margin-bottom: 6px;
  font-family: var(--font-mono);
}

.slice-preview-item canvas {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: white;
}

/* Inline math */
.math-inline {
  font-family: "KaTeX_Main", serif;
}

/* Color legend */
.color-legend {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin: 12px 0;
  font-size: 13px;
  color: var(--text-secondary);
}

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

.color-legend .swatch {
  width: 14px;
  height: 14px;
  border-radius: 3px;
}

/* ========== Feedback Section ========== */
.feedback-section {
  margin-top: 32px;
  padding: 24px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg, 12px);
}

.feedback-header h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--text-primary);
}

.feedback-desc {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.feedback-input-area {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.feedback-input-area textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.5;
  resize: vertical;
  color: var(--text-primary);
  background: white;
  box-sizing: border-box;
  transition: border-color 0.2s;
}

.feedback-input-area textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-light);
}

.feedback-input-footer {
  display: flex;
  align-items: center;
  gap: 12px;
}

#feedback-char-count {
  font-size: 12px;
  color: var(--text-tertiary, #999);
  font-family: var(--font-mono);
  transition: color 0.2s;
}

#feedback-char-count.char-warning {
  color: #e67e22;
}

#feedback-char-count.char-over {
  color: #e74c3c;
}

#feedback-submit-btn {
  margin-left: auto;
  padding: 8px 20px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: all 0.2s;
}

#feedback-submit-btn:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

#feedback-submit-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* Toast notification */
.feedback-toast {
  padding: 12px 16px;
  margin-top: 12px;
  border-radius: 8px;
  font-size: 14px;
  text-align: center;
  transition: opacity 0.3s;
}

.feedback-toast.hidden {
  display: none;
}

.feedback-toast.success {
  background: #e8f5e9;
  color: #2e7d32;
  border: 1px solid #a5d6a7;
}

.feedback-toast.warn {
  background: #fff3e0;
  color: #e65100;
  border: 1px solid #ffcc80;
}

.feedback-toast.error {
  background: #ffebee;
  color: #c62828;
  border: 1px solid #ef9a9a;
}

/* Tab container */
.tab-container {
  margin: 16px 0;
}

.tab-headers {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--border-color);
}

.tab-headers button {
  padding: 8px 16px;
  border: none;
  background: none;
  cursor: pointer;
  font-size: 13px;
  font-family: var(--font-sans);
  color: var(--text-secondary);
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all 0.2s;
}

.tab-headers button.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 500;
}

.tab-content {
  padding: 16px 0;
  display: none;
}

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

.lesson-optional-banner {
  margin: 0 0 16px;
  padding: 10px 14px;
  border-radius: 8px;
  border-left: 3px solid var(--amber);
  background: var(--amber-light);
  font-size: 14px;
  color: var(--text-secondary);
}

.lesson-link {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.lesson-link:hover {
  text-decoration: underline;
}

.lesson-axioms-details {
  margin: 16px 0;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background: var(--bg-secondary);
}

.lesson-axioms-details > summary {
  cursor: pointer;
  padding: 12px 16px;
  font-weight: 600;
  color: var(--text-primary);
  list-style: none;
}

.lesson-axioms-details > summary::-webkit-details-marker {
  display: none;
}

.lesson-axioms-details > summary::before {
  content: '▸ ';
  color: var(--accent);
}

.lesson-axioms-details[open] > summary::before {
  content: '▾ ';
}

.lesson-axioms-details .formula-block {
  margin: 0 16px 16px;
}