/* Shared styles for chapter content modules (js/content/**). Kept separate
   from css/style.css so the app shell and chapter content can evolve
   independently as more chapters are built. */

.chapter-content h2 {
  font-size: 20px;
  font-weight: 800;
  margin: 32px 0 12px;
}
.chapter-content h2:first-child {
  margin-top: 0;
}
.chapter-content h3 {
  font-size: 15px;
  font-weight: 700;
  color: var(--primary-dark);
  margin: 20px 0 8px;
}
.chapter-content p {
  color: var(--text-2);
  line-height: 1.8;
  font-size: 14.5px;
  margin-bottom: 10px;
}

.concept-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin: 12px 0 20px;
  box-shadow: var(--shadow);
}

.insight {
  display: flex;
  gap: 12px;
  background: #eef6ff;
  border: 1px solid #bfdbfe;
  border-radius: 12px;
  padding: 14px 18px;
  margin: 16px 0;
}
.insight .icon {
  font-size: 18px;
  flex-shrink: 0;
}
.insight p {
  margin: 0;
  color: var(--text);
}

.derivation {
  background: var(--surface-2);
  border-left: 3px solid var(--primary);
  border-radius: 0 12px 12px 0;
  padding: 14px 18px;
  margin: 14px 0;
}
.derivation .step {
  display: flex;
  gap: 10px;
  align-items: center;
  padding: 5px 0;
  font-size: 14.5px;
}
.derivation .step .label {
  font-size: 11px;
  color: var(--text-3);
  min-width: 76px;
  flex-shrink: 0;
}

/* Interactive demo */
.demo-area {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  margin: 16px 0 28px;
  box-shadow: var(--shadow);
}
.demo-equation {
  font-size: 20px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 18px;
  font-family: "Cambria Math", Cambria, serif;
}
.slider-group {
  margin: 14px 0;
}
.slider-group label {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: var(--text-2);
  margin-bottom: 6px;
}
.slider-group label span {
  color: var(--primary-dark);
  font-weight: 700;
  font-family: monospace;
}
input[type="range"] {
  width: 100%;
  accent-color: var(--primary);
}
.demo-values {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 16px 0;
}
.demo-value-box {
  background: var(--surface-2);
  border-radius: 10px;
  padding: 12px 14px;
  text-align: center;
}
.demo-value-box .demo-label {
  font-size: 11px;
  color: var(--text-3);
  margin-bottom: 4px;
}
.demo-value-box .demo-number {
  font-size: 22px;
  font-weight: 700;
  font-family: monospace;
}
.balance-indicator {
  text-align: center;
  font-weight: 700;
  padding: 10px;
  border-radius: 10px;
  font-size: 14px;
}
.balance-indicator.balanced {
  background: var(--success-bg);
  color: var(--success-text);
}
.balance-indicator.unbalanced {
  background: var(--surface-2);
  color: var(--text-2);
}

/* Practice area */
.practice-area {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  margin: 16px 0;
  box-shadow: var(--shadow);
}
.practice-progress {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: var(--text-2);
  margin-bottom: 16px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}
.mastery-pill {
  font-size: 11px;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 99px;
}
.mastery-pill.mastered {
  background: var(--success-bg);
  color: var(--success-text);
}
.mastery-pill.practicing {
  background: #fef3c7;
  color: #b45309;
}

.question-prompt {
  font-size: 15.5px;
  line-height: 1.8;
  margin-bottom: 16px;
}
.answer-row {
  display: flex;
  gap: 10px;
  margin-bottom: 14px;
  flex-wrap: wrap;
}
.answer-row input {
  flex: 1;
  min-width: 140px;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 15px;
  font-family: monospace;
}
.answer-row button,
.next-question-btn {
  padding: 10px 22px;
  border-radius: 10px;
  border: none;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  background: var(--primary);
  color: #fff;
}
.answer-row button:hover,
.next-question-btn:hover {
  background: var(--primary-dark);
}
.next-question-btn {
  background: var(--surface-2);
  color: var(--text);
  margin-top: 10px;
}
.next-question-btn:hover {
  background: var(--border);
}

.feedback {
  border-radius: 10px;
  padding: 12px 16px;
  margin: 10px 0;
  font-size: 14px;
  line-height: 1.7;
}
.feedback.correct {
  background: var(--success-bg);
  color: var(--success-text);
}
.feedback.incorrect {
  background: #fee2e2;
  color: #b91c1c;
}