/* ============================
   Lesson Header
============================ */
.lesson-header {
  background: linear-gradient(135deg, color-mix(in srgb, var(--ch-color, #5C6BC0) 85%, #000) 0%, var(--ch-color, #5C6BC0) 60%, color-mix(in srgb, var(--ch-color, #5C6BC0) 70%, white) 100%);
  color: white;
  padding: 36px 0 60px;
  position: relative;
  overflow: hidden;
}

/* Animated dots background */
.lesson-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle, rgba(255,255,255,0.12) 1px, transparent 1px);
  background-size: 28px 28px;
  animation: dot-drift 12s linear infinite;
}
@keyframes dot-drift {
  0% { transform: translate(0,0); }
  100% { transform: translate(28px, 28px); }
}

.lesson-header::after {
  content: '';
  position: absolute;
  bottom: -1px; left: 0; right: 0;
  height: 40px;
  background: var(--color-bg);
  border-radius: 50% 50% 0 0 / 40px 40px 0 0;
}

.lesson-header-inner { position: relative; z-index: 1; }

.lesson-breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 700;
  opacity: 0.85;
  margin-bottom: 14px;
}
.lesson-breadcrumb a { color: rgba(255,255,255,0.85); }
.lesson-breadcrumb a:hover { color: white; }
.lesson-breadcrumb-sep { opacity: 0.6; }

.lesson-chapter-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255,255,255,0.22);
  color: white;
  padding: 5px 16px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 800;
  margin-bottom: 14px;
  backdrop-filter: blur(4px);
}

.lesson-title-h1 {
  font-size: 1.9rem;
  font-weight: 900;
  line-height: 1.2;
  margin-bottom: 18px;
  text-shadow: 0 2px 8px rgba(0,0,0,0.25);
}

.lesson-info-row { display: flex; gap: 10px; flex-wrap: wrap; }
.lesson-info-item {
  display: flex;
  align-items: center;
  gap: 6px;
  background: rgba(255,255,255,0.2);
  backdrop-filter: blur(4px);
  padding: 6px 16px;
  border-radius: 20px;
  font-size: 14px;
  font-weight: 700;
}

.lesson-progress-bar {
  background: rgba(255,255,255,0.25);
  height: 7px;
  border-radius: 4px;
  margin-top: 20px;
  overflow: hidden;
}
.lesson-progress-fill {
  height: 100%;
  background: white;
  border-radius: 4px;
  transition: width 0.4s ease;
}

/* ============================
   Lesson Body
============================ */
.lesson-body { padding: 28px 0 48px; }

/* ============================
   Section Titles
============================ */
.lesson-section { margin-bottom: 52px; }

.section-title {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 22px;
  font-weight: 900;
  color: var(--color-text);
  margin-bottom: 20px;
}

.section-number {
  width: 42px;
  height: 42px;
  background: linear-gradient(135deg, var(--ch-color, #5C6BC0), color-mix(in srgb, var(--ch-color, #5C6BC0) 70%, #000));
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  font-weight: 900;
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(0,0,0,0.18);
}

/* ============================
   Parts Grid
============================ */
.parts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
  margin: 16px 0;
}

.part-card {
  background: white;
  border-radius: 18px;
  padding: 18px 12px;
  text-align: center;
  border: 2px solid var(--color-border);
  transition: transform 0.2s cubic-bezier(.34,1.56,.64,1), box-shadow 0.2s ease, border-color 0.2s;
  cursor: default;
}
.part-card:hover {
  transform: translateY(-4px) scale(1.04);
  box-shadow: var(--shadow-md);
  border-color: var(--ch-color, #5C6BC0);
}
.part-icon { font-size: 2.4rem; margin-bottom: 8px; display: block; line-height: 1; }
.part-name { font-size: 15px; font-weight: 800; display: block; margin-bottom: 3px; }
.part-qty { font-size: 13px; color: var(--color-text-light); display: block; font-weight: 600; }

/* ── Mini Resistor Visual (part card icon) ── */
.res-mini {
  display: inline-flex;
  align-items: center;
  vertical-align: middle;
  margin-bottom: 4px;
}
.res-mini-lead {
  width: 18px; height: 4px;
  background: #9E9E9E;
  border-radius: 2px;
  flex-shrink: 0;
}
.res-mini-body {
  width: 54px; height: 22px;
  background: #D7CCC8;
  border-radius: 7px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  position: relative;
  overflow: hidden;
  box-shadow: 0 2px 6px rgba(0,0,0,0.18);
  flex-shrink: 0;
}
.res-mini-body::before {
  content: '';
  position: absolute;
  top: 3px; left: 5px; right: 5px;
  height: 5px;
  background: rgba(255,255,255,0.38);
  border-radius: 4px;
  pointer-events: none;
}
.res-mini-band {
  width: 7px;
  height: 100%;
  flex-shrink: 0;
}

/* ============================
   Info Boxes
============================ */
.info-box {
  background: #EEF0FF;
  border-left: 5px solid var(--color-primary);
  border-radius: 0 18px 18px 0;
  padding: 16px 20px;
  margin: 16px 0;
}
.info-box.warning { background: #FFF8E1; border-color: var(--color-warning); }
.info-box.success { background: #E8F5E9; border-color: var(--color-success); }
.info-box.danger  { background: #FFEBEE; border-color: var(--color-error); }

.info-box-title {
  font-size: 16px;
  font-weight: 900;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

/* ============================
   Circuit Diagram
============================ */
.circuit-svg-wrapper {
  background: white;
  border-radius: 22px;
  padding: 24px;
  border: 2px solid var(--color-border);
  margin: 16px 0;
  overflow-x: auto;
  box-shadow: var(--shadow-sm);
}
.circuit-caption {
  font-size: 13px;
  color: var(--color-text-light);
  margin-top: 10px;
  font-weight: 700;
  text-align: center;
}

/* ============================
   Checklist
============================ */
.checklist { display: flex; flex-direction: column; gap: 10px; margin: 16px 0; }

.checklist-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  background: white;
  border-radius: 18px;
  padding: 18px 20px;
  border: 2px solid var(--color-border);
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s, transform 0.15s;
  user-select: none;
}
.checklist-item:hover { border-color: var(--ch-color, #5C6BC0); transform: translateX(3px); }
.checklist-item.checked { background: #E8F5E9; border-color: var(--color-success); transform: none; }

.checklist-item input[type="checkbox"] {
  width: 24px; height: 24px;
  flex-shrink: 0;
  cursor: pointer;
  accent-color: var(--color-success);
  margin-top: 3px;
}

.checklist-step-num {
  width: 30px; height: 30px;
  background: linear-gradient(135deg, var(--ch-color, #5C6BC0), color-mix(in srgb, var(--ch-color,#5C6BC0) 70%, #000));
  color: white;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 14px; font-weight: 900;
  flex-shrink: 0;
  box-shadow: 0 3px 8px rgba(0,0,0,0.15);
}
.checklist-item.checked .checklist-step-num { background: linear-gradient(135deg, #00C853, #00897B); }

.checklist-content { flex: 1; }
.checklist-content strong { display: block; font-weight: 900; margin-bottom: 4px; font-size: 15px; }
.checklist-content p { font-size: 13px; color: var(--color-text-light); margin: 0; line-height: 1.55; }
.checklist-item.checked .checklist-content strong,
.checklist-item.checked .checklist-content p { color: #2E7D32; }

#checklist-complete-banner {
  display: none;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: linear-gradient(135deg, #E8F5E9, #C8E6C9);
  border: 3px solid #00C853;
  border-radius: 22px;
  padding: 20px 28px;
  margin-top: 14px;
  font-weight: 900;
  font-size: 20px;
  color: #2E7D32;
  animation: pop-in 0.4s cubic-bezier(.34,1.56,.64,1);
}
@keyframes pop-in {
  0% { transform: scale(0.8); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}

/* ============================
   Quiz Section
============================ */
#quiz-container {
  background: white;
  border-radius: 24px;
  padding: 28px;
  border: 2px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.quiz-progress { display: flex; align-items: center; gap: 12px; margin-bottom: 22px; }
.quiz-num { font-size: 13px; font-weight: 900; color: var(--color-text-light); white-space: nowrap; }
.quiz-progress-bar { flex: 1; height: 9px; background: var(--color-border); border-radius: 5px; overflow: hidden; }
.quiz-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--ch-color, #5C6BC0), color-mix(in srgb, var(--ch-color,#5C6BC0) 50%, #FFD600));
  border-radius: 5px;
  transition: width 0.4s ease;
}

.quiz-question { display: flex; gap: 16px; align-items: flex-start; margin-bottom: 22px; }
.quiz-mascot { font-size: 2.5rem; flex-shrink: 0; line-height: 1; transition: transform 0.3s; }
.quiz-text { font-size: 19px; font-weight: 800; line-height: 1.5; margin: 0; }

.quiz-options { display: flex; flex-direction: column; gap: 10px; }

.quiz-option {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 15px 20px;
  background: #F8F9FF;
  border: 2px solid #E8EEFF;
  border-radius: 16px;
  font-family: var(--font-main);
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  text-align: left;
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
  width: 100%;
}
.quiz-option:hover:not(:disabled) {
  border-color: var(--ch-color, #5C6BC0);
  background: color-mix(in srgb, var(--ch-color, #5C6BC0) 8%, white);
  transform: translateX(5px);
}
.quiz-option:disabled { cursor: default; transform: none; }
.quiz-option.correct { background: #E8F5E9; border-color: #00C853; color: #1B5E20; }
.quiz-option.wrong   { background: #FFEBEE; border-color: #FF1744; color: #B71C1C; }

.quiz-option-label {
  width: 34px; height: 34px;
  background: linear-gradient(135deg, var(--ch-color, #5C6BC0), color-mix(in srgb, var(--ch-color,#5C6BC0) 70%, #000));
  color: white;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 14px; font-weight: 900;
  flex-shrink: 0;
}
.quiz-option.correct .quiz-option-label { background: linear-gradient(135deg, #00C853, #00897B); }
.quiz-option.wrong   .quiz-option-label { background: linear-gradient(135deg, #FF1744, #C62828); }

.quiz-explanation {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 16px 20px;
  border-radius: 16px;
  margin-top: 16px;
  font-size: 14px;
  line-height: 1.65;
  animation: pop-in 0.3s cubic-bezier(.34,1.56,.64,1);
}
.quiz-explanation.correct { background: #E8F5E9; border: 2px solid #00C853; }
.quiz-explanation.wrong   { background: #FFEBEE; border: 2px solid #FFCDD2; }
.quiz-explanation-icon { font-size: 1.6rem; flex-shrink: 0; }
.quiz-explanation strong { display: block; font-size: 16px; margin-bottom: 4px; }

.quiz-next-btn {
  margin-top: 20px;
  width: 100%;
  padding: 18px 24px;
  font-size: 18px;
  font-weight: 900;
  letter-spacing: 0.04em;
  border-radius: 20px;
  background: linear-gradient(135deg, #FF9100, #FF5722);
  color: white;
  box-shadow: 0 6px 20px rgba(255,87,34,0.45), 0 2px 6px rgba(0,0,0,0.15);
  border: none;
  animation: quiz-next-pulse 2s ease-in-out infinite;
}
.quiz-next-btn:hover:not(:disabled) {
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 10px 28px rgba(255,87,34,0.55), 0 3px 8px rgba(0,0,0,0.18);
  animation: none;
}
@keyframes quiz-next-pulse {
  0%, 100% { box-shadow: 0 6px 20px rgba(255,87,34,0.45), 0 2px 6px rgba(0,0,0,0.15); }
  50%       { box-shadow: 0 8px 28px rgba(255,87,34,0.65), 0 3px 10px rgba(0,0,0,0.18); transform: translateY(-2px); }
}

/* Result screen */
.quiz-result { text-align: center; padding: 12px; }
.quiz-result-emoji { font-size: 4.5rem; margin-bottom: 14px; animation: mascot-bounce 1s ease-in-out infinite; }
@keyframes mascot-bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}
.quiz-result-title { font-size: 24px; font-weight: 900; margin-bottom: 22px; }
.score-num { font-size: 3.5rem; font-weight: 900; color: var(--ch-color, #5C6BC0); }
.score-sep, .score-total { font-size: 2.2rem; font-weight: 800; color: #9FA8DA; }
.score-label { display: block; font-size: 13px; color: #9FA8DA; margin-top: 4px; }

.quiz-result-bar {
  width: 100%; max-width: 320px;
  height: 14px;
  background: var(--color-border);
  border-radius: 7px;
  margin: 12px auto 8px;
  overflow: hidden;
}
.quiz-result-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--ch-color, #5C6BC0), #FFD600);
  border-radius: 7px;
  transition: width 0.9s cubic-bezier(.34,1.56,.64,1);
}
.quiz-result-pct { font-size: 20px; font-weight: 900; color: var(--ch-color, #5C6BC0); margin-bottom: 22px; }

/* ============================
   Lesson Complete Banner
============================ */
#lesson-complete-banner {
  display: none;
  flex-direction: column;
  align-items: center;
  text-align: center;
  background: linear-gradient(135deg, #FFF8E1, #FFFDE7, #FFF3E0);
  border: 3px solid #FFD600;
  border-radius: 28px;
  padding: 44px 32px;
  margin: 32px 0;
  gap: 14px;
  animation: pop-in 0.5s cubic-bezier(.34,1.56,.64,1);
  box-shadow: 0 8px 32px rgba(255,214,0,0.3);
}
.complete-emoji { font-size: 4.5rem; animation: mascot-bounce 1.5s ease-in-out infinite; }
.complete-title { font-size: 2rem; font-weight: 900; color: #E65100; }
.complete-subtitle { font-size: 18px; color: #9FA8DA; }
.complete-next-btn { margin-top: 8px; }

/* ============================
   Circuit Puzzle Game
============================ */
.cp-wrapper { padding: 4px 0; }

.cp-instruction {
  display: flex;
  align-items: center;
  gap: 14px;
  background: linear-gradient(135deg, #EEF0FF, #E8F5FF);
  border-radius: 20px;
  padding: 18px 22px;
  margin-bottom: 24px;
  font-size: 16px;
  font-weight: 700;
  border: 2px solid #C5CAE9;
}
.cp-mascot { font-size: 2.6rem; flex-shrink: 0; }

.cp-tray {
  display: flex;
  gap: 14px;
  margin-bottom: 28px;
  flex-wrap: wrap;
  justify-content: center;
}

.cp-card {
  background: white;
  border: 3px solid var(--color-border);
  border-radius: 20px;
  padding: 18px 16px;
  text-align: center;
  cursor: grab;
  transition: transform 0.2s cubic-bezier(.34,1.56,.64,1), border-color 0.15s, box-shadow 0.15s, opacity 0.2s;
  min-width: 115px;
  user-select: none;
  box-shadow: var(--shadow-sm);
}
.cp-card:hover:not(.placed) {
  transform: translateY(-6px) rotate(2deg);
  border-color: var(--ch-color, #5C6BC0);
  box-shadow: var(--shadow-md);
}
.cp-card.selected { border-color: var(--ch-color, #5C6BC0); background: #EEF0FF; transform: scale(1.06); }
.cp-card.placed   { opacity: 0.3; cursor: default; }
.cp-card.dragging { opacity: 0.45; transform: scale(0.92); }

.cp-card-icon { font-size: 2.7rem; margin-bottom: 8px; display: block; }
.cp-card-name { font-size: 15px; font-weight: 900; display: block; margin-bottom: 4px; }
.cp-card-desc { font-size: 12px; color: var(--color-text-light); font-weight: 600; }

.cp-circuit {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  margin-bottom: 22px;
  flex-wrap: wrap;
  background: #F8F9FF;
  border-radius: 22px;
  padding: 28px 20px;
  border: 2px dashed #C5CAE9;
}

.cp-wire-start, .cp-wire-end {
  width: 28px; height: 5px;
  background: #C5CAE9;
  border-radius: 3px;
  transition: background 0.5s, box-shadow 0.5s;
}
.cp-wire-start.current-flow, .cp-wire-end.current-flow {
  background: #FFD600;
  box-shadow: 0 0 10px rgba(255,214,0,0.8);
}

.cp-wire-arrow {
  font-size: 1.6rem;
  color: #C5CAE9;
  font-weight: 900;
  margin: 0 6px;
  transition: color 0.5s;
}
.cp-wire-arrow.current-flow { color: #FFD600; text-shadow: 0 0 10px rgba(255,214,0,0.8); }

.cp-slot {
  background: white;
  border: 3px dashed #C5CAE9;
  border-radius: 18px;
  width: 120px;
  min-height: 110px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color 0.2s, background 0.2s, box-shadow 0.3s;
  position: relative;
}
.cp-slot.drag-over { border-color: var(--ch-color, #5C6BC0); background: #EEF0FF; }
.cp-slot.filled    { border-style: solid; border-color: var(--ch-color, #5C6BC0); }
.cp-slot.lit       { border-color: #FFD600; background: #FFFDE7; box-shadow: 0 0 16px rgba(255,214,0,0.5); }

.cp-slot-inner { text-align: center; padding: 8px; width: 100%; }
.cp-slot-label { font-size: 2.2rem; color: #C5CAE9; font-weight: 900; }
.cp-slot-icon  { font-size: 2.2rem; display: block; margin-bottom: 4px; }
.cp-slot-name  { font-size: 13px; font-weight: 900; }

.cp-slot-remove {
  position: absolute;
  top: -10px; right: -10px;
  width: 26px; height: 26px;
  border-radius: 50%;
  background: linear-gradient(135deg, #FF1744, #C62828);
  color: white;
  border: none;
  cursor: pointer;
  font-size: 12px; font-weight: 900;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 2px 8px rgba(255,23,68,0.4);
  transition: transform 0.15s;
}
.cp-slot-remove:hover { transform: scale(1.2); }

.cp-check-btn { display: block; width: 100%; max-width: 320px; margin: 0 auto 22px; }

.cp-result {
  border-radius: 18px;
  padding: 20px 24px;
  display: flex;
  gap: 16px;
  align-items: flex-start;
  animation: pop-in 0.35s cubic-bezier(.34,1.56,.64,1);
}
.cp-result.correct { background: #E8F5E9; border: 2px solid #00C853; }
.cp-result.wrong   { background: #FFEBEE; border: 2px solid #FFCDD2; }
.cp-result-icon { font-size: 2.2rem; flex-shrink: 0; }
.cp-result-text strong { display: block; font-size: 18px; margin-bottom: 6px; }
.cp-result-text ul { list-style: none; margin: 8px 0; }
.cp-result-text li { padding: 2px 0; font-size: 14px; }
.hint-ok { color: #2E7D32; }
.hint-ng { color: #C62828; }

/* ============================
   Safety / Component boxes
============================ */
.safety-box {
  background: #FFF8E1;
  border: 3px solid #FFB300;
  border-radius: 20px;
  padding: 20px 24px;
  margin: 20px 0;
  display: flex;
  gap: 14px;
  align-items: flex-start;
}
.safety-icon { font-size: 2.2rem; flex-shrink: 0; }
.safety-title { font-size: 17px; font-weight: 900; color: #E65100; margin-bottom: 8px; }

/* ============================
   Responsive
============================ */
@media (max-width: 600px) {
  .lesson-title-h1 { font-size: 1.3rem; }
  .parts-grid { grid-template-columns: repeat(2, 1fr); }
  .cp-tray { gap: 10px; }
  .cp-card { min-width: 95px; padding: 14px 12px; }
  .cp-slot { width: 95px; min-height: 95px; }
  .quiz-text { font-size: 17px; }
}

/* ============================
   Compat: Lessons 19-24
   (lesson-hero / lesson-main / section-num)
============================ */

/* ── Slim top nav bar ── */
.lesson-nav {
  background: white;
  border-bottom: 2px solid var(--color-border, #E8EAF6);
  padding: 0 24px;
  height: 58px;
  display: flex;
  align-items: center;
  gap: 16px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}
.nav-back {
  font-weight: 800;
  color: var(--ch-color, #5C6BC0);
  font-size: 14px;
  text-decoration: none;
  white-space: nowrap;
  transition: opacity 0.2s;
}
.nav-back:hover { opacity: 0.7; }
.nav-lesson-info {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 700;
  flex: 1;
  color: var(--color-text, #1A1A2E);
}
.nav-chapter { font-weight: 900; }
.nav-title   { opacity: 0.65; }

/* ── Hero header ── */
.lesson-hero {
  color: white;
  padding: 40px 0 60px;
  position: relative;
  overflow: hidden;
}
/* animated dot pattern (reuse dot-drift from lesson-header) */
.lesson-hero::before {
  content: '';
  position: absolute; inset: 0;
  background-image: radial-gradient(circle, rgba(255,255,255,0.12) 1px, transparent 1px);
  background-size: 28px 28px;
  animation: dot-drift 12s linear infinite;
}
/* wave cutoff at bottom */
.lesson-hero::after {
  content: '';
  position: absolute;
  bottom: -1px; left: 0; right: 0;
  height: 40px;
  background: var(--color-bg, #F0F4FF);
  border-radius: 50% 50% 0 0 / 40px 40px 0 0;
}
.lesson-hero-content {
  position: relative;
  z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px 0 28px;
  padding-right: 96px; /* room for floating icon */
}
.lesson-num-badge {
  display: inline-flex;
  align-items: center;
  background: rgba(255,255,255,0.22);
  color: white;
  padding: 5px 16px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 800;
  margin-bottom: 14px;
  backdrop-filter: blur(4px);
}
.lesson-hero-title {
  font-size: 1.9rem;
  font-weight: 900;
  line-height: 1.25;
  margin-bottom: 14px;
  text-shadow: 0 2px 8px rgba(0,0,0,0.25);
}
.lesson-hero-title span {
  display: block;
  font-size: 1.35rem;
  opacity: 0.88;
  margin-top: 4px;
}
.lesson-hero-desc {
  font-size: 15px;
  opacity: 0.88;
  margin-bottom: 18px;
  max-width: 580px;
  line-height: 1.6;
}
.lesson-hero-badges {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}
.hero-badge {
  background: rgba(255,255,255,0.2);
  backdrop-filter: blur(4px);
  padding: 6px 16px;
  border-radius: 20px;
  font-size: 14px;
  font-weight: 700;
}
.lesson-hero-icon {
  position: absolute;
  right: 6%;
  top: 50%;
  transform: translateY(-50%);
  font-size: 5rem;
  opacity: 0.22;
  z-index: 1;
  pointer-events: none;
}

/* ── Main body ── */
.lesson-main {
  padding: 28px 0 52px;
  background: var(--color-bg, #F0F4FF);
  min-height: 60vh;
}
/* Container-less sections: apply max-width directly */
.lesson-main > .lesson-section {
  max-width: 1100px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* ── Section number circles (①②③ → styled like section-number) ── */
.section-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  min-width: 42px;
  background: linear-gradient(135deg, var(--ch-color, #5C6BC0), color-mix(in srgb, var(--ch-color, #5C6BC0) 70%, #000));
  color: white;
  border-radius: 50%;
  font-size: 1rem;
  font-weight: 900;
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(0,0,0,0.18);
}

@media (max-width: 600px) {
  .lesson-hero-title { font-size: 1.35rem; }
  .lesson-hero-title span { font-size: 1.1rem; }
  .lesson-hero-content { padding-right: 28px; }
  .lesson-hero-icon { display: none; }
}