/* ============================================================
   QUANTUM CODEX — Lesson Framework Styles
   All lesson template sections, scroll storytelling, progress,
   guided mode, roadmap, and interactive educational components.
   ============================================================ */

/* ──────────────────────────────────────────
   LESSON LAYOUT WRAPPER
   ────────────────────────────────────────── */
.lesson-page {
  min-height: 100vh;
  background: var(--bg-void);
}

.lesson-content {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 60px) 120px;
}

/* ──────────────────────────────────────────
   READING PROGRESS BAR
   ────────────────────────────────────────── */
.lesson-progress-bar {
  position: fixed;
  top: var(--nav-height);
  left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-indigo));
  z-index: 1000;
  transition: width 80ms linear;
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.6);
}

/* ──────────────────────────────────────────
   LESSON HERO
   ────────────────────────────────────────── */
.lesson-hero {
  position: relative;
  min-height: 70vh;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  padding: 0 clamp(20px, 5vw, 100px) 64px;
  overflow: hidden;
  background: var(--bg-void);
}

.lesson-hero-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
}

.lesson-hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    transparent 0%,
    rgba(4, 6, 13, 0.3) 60%,
    var(--bg-void) 100%
  );
  z-index: 1;
}

.lesson-hero-content {
  position: relative;
  z-index: 2;
  max-width: 860px;
}

.lesson-hero-eyebrow {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-cyan);
  margin-bottom: 16px;
}

.lesson-hero-eyebrow-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-cyan);
  box-shadow: var(--glow-info);
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.7); }
}

.lesson-hero-title {
  font-size: clamp(2.8rem, 6vw, 5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.05;
  color: var(--text-primary);
  margin-bottom: 20px;
}

.lesson-hero-subtitle {
  font-size: clamp(1rem, 1.5vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 600px;
  line-height: 1.7;
  margin-bottom: 32px;
}

.lesson-hero-meta {
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
}

.lesson-hero-meta-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.lesson-hero-meta-item svg { color: var(--accent-cyan); }

/* ──────────────────────────────────────────
   LESSON STICKY PROGRESS NAV (right-side)
   ────────────────────────────────────────── */
.lesson-section-nav {
  position: fixed;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 100;
  opacity: 0;
  transition: opacity var(--dur-base) ease;
}

.lesson-section-nav.visible { opacity: 1; }

.lesson-section-nav-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--border-soft);
  border: 1px solid var(--border-subtle);
  cursor: pointer;
  transition: all var(--dur-fast) ease;
  position: relative;
}

.lesson-section-nav-dot::after {
  content: attr(data-label);
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  white-space: nowrap;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-fast) ease;
  background: var(--bg-deep);
  padding: 4px 8px;
  border-radius: 4px;
  border: 1px solid var(--border-subtle);
}

.lesson-section-nav-dot:hover::after { opacity: 1; }

.lesson-section-nav-dot.active {
  background: var(--accent-cyan);
  border-color: var(--accent-cyan);
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.6);
  transform: scale(1.4);
}

/* ──────────────────────────────────────────
   LESSON SECTIONS — Scroll Reveal
   ────────────────────────────────────────── */
.lesson-section {
  padding: 80px 0;
  border-bottom: 1px solid var(--border-subtle);
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.7s var(--ease-smooth), transform 0.7s var(--ease-smooth);
}

.lesson-section.revealed {
  opacity: 1;
  transform: translateY(0);
}

.lesson-section:last-child { border-bottom: none; }

.lesson-section-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-cyan);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.lesson-section-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, rgba(0, 212, 255, 0.3), transparent);
  max-width: 120px;
}

.lesson-section-title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
  color: var(--text-primary);
  margin-bottom: 24px;
}

.lesson-body-text {
  font-size: 1.05rem;
  line-height: 1.85;
  color: var(--text-secondary);
  margin-bottom: 24px;
  font-family: var(--font-sans);
}

.lesson-body-text + .lesson-body-text { margin-top: -8px; }

/* Inline highlight */
.lesson-highlight {
  color: var(--accent-cyan);
  font-weight: 600;
}

/* ──────────────────────────────────────────
   QUICK OVERVIEW CARD
   ────────────────────────────────────────── */
.lesson-overview {
  padding: 48px 0;
  border-bottom: 1px solid var(--border-subtle);
}

.lesson-overview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1px;
  background: var(--border-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-top: 32px;
}

.lesson-overview-item {
  padding: 24px;
  background: var(--bg-card);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.lesson-overview-item-label {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.lesson-overview-item-value {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* ──────────────────────────────────────────
   HISTORICAL TIMELINE
   ────────────────────────────────────────── */
.lesson-timeline-container {
  position: relative;
  padding-left: 48px;
  margin-top: 40px;
}

.lesson-timeline-line {
  position: absolute;
  left: 16px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent-cyan), var(--accent-indigo), transparent);
}

.lesson-timeline-event {
  position: relative;
  margin-bottom: 48px;
  opacity: 0;
  transform: translateX(-16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.lesson-timeline-event.revealed {
  opacity: 1;
  transform: translateX(0);
}

.lesson-timeline-event::before {
  content: '';
  position: absolute;
  left: -40px;
  top: 6px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--bg-void);
  border: 2px solid var(--accent-cyan);
  box-shadow: 0 0 10px rgba(0, 212, 255, 0.5);
  transition: box-shadow var(--dur-fast) ease;
}

.lesson-timeline-event:hover::before {
  box-shadow: var(--glow-cyan);
}

.lesson-timeline-year {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent-cyan);
  font-weight: 700;
  letter-spacing: 0.05em;
  margin-bottom: 6px;
}

.lesson-timeline-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.lesson-timeline-desc {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

/* ──────────────────────────────────────────
   INTERACTIVE DEMO CONTAINER
   ────────────────────────────────────────── */
.lesson-demo {
  margin: 48px 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border-soft);
  background: var(--bg-deep);
}

.lesson-demo-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-subtle);
  background: var(--bg-surface);
}

.lesson-demo-title {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  display: flex;
  align-items: center;
  gap: 8px;
}

.lesson-demo-title-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-cyan);
  animation: pulse-dot 2s infinite;
}

.lesson-demo-body {
  padding: 32px;
  min-height: 200px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

/* ──────────────────────────────────────────
   BOHR LESSON DEMO — live energy calculator
   ────────────────────────────────────────── */
.lesson-bohr-demo-inner {
  width: 100%;
  max-width: 640px;
}

.lesson-bohr-canvas-wrap {
  width: 100%;
  margin: 12px 0;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border-subtle);
}

.lesson-bohr-canvas-wrap canvas {
  display: block;
  width: 100%;
  height: auto;
}

.lesson-bohr-note {
  width: 100%;
  margin-top: 14px;
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--text-secondary);
  text-align: left;
}

.lesson-bohr-note::before {
  content: 'ℹ ';
  color: var(--accent-cyan);
}

/* ──────────────────────────────────────────
   CONCEPT HIGHLIGHT CARDS (Inline)
   ────────────────────────────────────────── */
.lesson-concept-highlight {
  display: flex;
  gap: 16px;
  padding: 20px 24px;
  background: rgba(0, 212, 255, 0.04);
  border: 1px solid rgba(0, 212, 255, 0.12);
  border-left: 4px solid var(--accent-cyan);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin: 32px 0;
}

.lesson-concept-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.lesson-concept-text { line-height: 1.7; color: var(--text-secondary); font-size: 1rem; }

/* Misconception — red tint */
.lesson-misconception {
  border-left-color: var(--color-error);
  background: rgba(255, 74, 74, 0.04);
  border-color: rgba(255, 74, 74, 0.15);
  border-left-color: var(--color-error);
}
.lesson-misconception .lesson-concept-text strong { color: var(--color-error); }

/* Real-world — amber tint */
.lesson-realworld {
  border-left-color: var(--color-warning);
  background: rgba(255, 184, 48, 0.04);
  border-color: rgba(255, 184, 48, 0.15);
}

/* Key insight — indigo tint */
.lesson-insight {
  border-left-color: var(--accent-indigo);
  background: rgba(124, 107, 255, 0.05);
  border-color: rgba(124, 107, 255, 0.15);
}

/* ──────────────────────────────────────────
   EQUATION BLOCK
   ────────────────────────────────────────── */
.lesson-equation {
  margin: 40px 0;
  padding: 40px 32px;
  text-align: center;
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  position: relative;
  overflow: hidden;
}

.lesson-equation::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(124, 107, 255, 0.06), transparent 70%);
  pointer-events: none;
}

.lesson-equation-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 20px;
}

.lesson-equation-body {
  font-size: clamp(1.4rem, 3vw, 2.1rem);
  color: var(--text-primary);
  line-height: 1.6;
}

/* KaTeX display math inside equation blocks */
.lesson-equation-body .katex-display {
  margin: 0;
}

.lesson-equation-body .katex {
  font-size: 1.05em;
}

/* Inline KaTeX inside lesson body text */
.lesson-body-text .katex,
.lesson-concept-text .katex,
.lesson-takeaway-list .katex,
.lesson-expandable-content .katex,
.lesson-timeline-desc .katex,
.lesson-equation-caption .katex {
  font-size: 1.02em;
  color: inherit;
}

.lesson-highlight .katex { color: var(--accent-cyan); }

/* ──────────────────────────────────────────
   MASTER EQUATION — term-highlighted diagram
   ────────────────────────────────────────── */
.qc-master-equation {
  margin: 8px 0 24px;
}

.qc-master-eq {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 6px 14px;
  padding: 34px 24px;
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  font-size: clamp(1.2rem, 2.6vw, 1.8rem);
  color: var(--text-primary);
  position: relative;
  overflow: hidden;
}

.qc-master-eq::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(124, 107, 255, 0.06), transparent 70%);
  pointer-events: none;
}

.qc-eq-term {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 8px;
  transition: opacity var(--dur-base) var(--ease-smooth),
              text-shadow var(--dur-base) var(--ease-smooth),
              background var(--dur-base) var(--ease-smooth),
              box-shadow var(--dur-base) var(--ease-smooth);
  cursor: default;
  outline: none;
}

.qc-eq-term .katex { font-size: 1em; }

.qc-eq-op {
  color: var(--text-muted);
  font-size: 0.9em;
  padding: 0 2px;
}

/* Term colours (also mirrored in legend swatches) */
.qc-eq-term[data-term="time"] { color: var(--accent-cyan); }
.qc-eq-term[data-term="kinetic"] { color: var(--accent-indigo); }
.qc-eq-term[data-term="potential"] { color: var(--accent-magenta); }
.qc-eq-term[data-term="wavefn"] { color: var(--accent-green); }

/* Hover illumination — soft glow, no flashing */
.qc-master-equation.is-dimmed .qc-eq-term:not(.is-lit) {
  opacity: 0.28;
}

.qc-eq-term.is-lit {
  opacity: 1;
  background: rgba(255, 255, 255, 0.06);
}

.qc-eq-term[data-term="time"].is-lit { text-shadow: 0 0 18px rgba(0, 212, 255, 0.75); box-shadow: 0 0 14px rgba(0, 212, 255, 0.28); }
.qc-eq-term[data-term="kinetic"].is-lit { text-shadow: 0 0 18px rgba(124, 107, 255, 0.75); box-shadow: 0 0 14px rgba(124, 107, 255, 0.28); }
.qc-eq-term[data-term="potential"].is-lit { text-shadow: 0 0 18px rgba(224, 64, 251, 0.75); box-shadow: 0 0 14px rgba(224, 64, 251, 0.28); }
.qc-eq-term[data-term="wavefn"].is-lit { text-shadow: 0 0 18px rgba(0, 255, 157, 0.75); box-shadow: 0 0 14px rgba(0, 255, 157, 0.28); }

.qc-eq-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-top: 18px;
}

.qc-eq-legend-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--bg-surface);
  border: 1px solid var(--border-soft);
  border-radius: 100px;
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: all var(--dur-fast) ease;
}

.qc-eq-legend-item:hover {
  background: var(--bg-card);
  border-color: var(--border-accent);
}

.qc-eq-legend-item.is-lit {
  border-color: var(--border-accent);
  color: var(--text-primary);
  transform: translateY(-1px);
}

.qc-eq-swatch {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

.qc-eq-legend-item[data-term="time"] .qc-eq-swatch { background: var(--accent-cyan); box-shadow: 0 0 8px rgba(0, 212, 255, 0.6); }
.qc-eq-legend-item[data-term="kinetic"] .qc-eq-swatch { background: var(--accent-indigo); box-shadow: 0 0 8px rgba(124, 107, 255, 0.6); }
.qc-eq-legend-item[data-term="potential"] .qc-eq-swatch { background: var(--accent-magenta); box-shadow: 0 0 8px rgba(224, 64, 251, 0.6); }
.qc-eq-legend-item[data-term="wavefn"] .qc-eq-swatch { background: var(--accent-green); box-shadow: 0 0 8px rgba(0, 255, 157, 0.6); }

.qc-eq-legend-item[data-term="time"].is-lit { box-shadow: 0 0 16px rgba(0, 212, 255, 0.25); }
.qc-eq-legend-item[data-term="kinetic"].is-lit { box-shadow: 0 0 16px rgba(124, 107, 255, 0.25); }
.qc-eq-legend-item[data-term="potential"].is-lit { box-shadow: 0 0 16px rgba(224, 64, 251, 0.25); }
.qc-eq-legend-item[data-term="wavefn"].is-lit { box-shadow: 0 0 16px rgba(0, 255, 157, 0.25); }

.qc-eq-note {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 12px;
  font-family: var(--font-sans);
}

.qc-eq-term:focus-visible,
.qc-eq-legend-item:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  .qc-eq-term, .qc-eq-legend-item { transition: none !important; }
  .qc-master-equation.is-dimmed .qc-eq-term:not(.is-lit) { opacity: 0.5; }
}

.lesson-equation-caption {
  margin-top: 16px;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-family: var(--font-sans);
}

/* ──────────────────────────────────────────
   KEY TAKEAWAYS (end of lesson)
   ────────────────────────────────────────── */
.lesson-takeaways {
  margin: 48px 0;
  padding: 40px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
}

.lesson-takeaways::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-indigo));
}

.lesson-takeaways-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent-cyan);
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  letter-spacing: 0.04em;
}

.lesson-takeaway-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.lesson-takeaway-list li {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  font-size: 1rem;
  line-height: 1.65;
  color: var(--text-secondary);
}

.lesson-takeaway-list li::before {
  content: '✦';
  color: var(--accent-cyan);
  font-size: 0.7rem;
  margin-top: 5px;
  flex-shrink: 0;
}

/* ──────────────────────────────────────────
   SIMULATION LAUNCH PANEL (in-lesson)
   ────────────────────────────────────────── */
.lesson-sim-launch {
  margin: 56px 0;
  padding: 36px 40px;
  background: linear-gradient(
    135deg,
    rgba(0, 212, 255, 0.05) 0%,
    rgba(124, 107, 255, 0.05) 100%
  );
  border: 1px solid rgba(0, 212, 255, 0.2);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  transition: border-color var(--dur-fast) ease, box-shadow var(--dur-fast) ease;
}

.lesson-sim-launch:hover {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 30px rgba(0, 212, 255, 0.1);
}

.lesson-sim-launch-info { flex: 1; }

.lesson-sim-launch-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  color: var(--accent-cyan);
  text-transform: uppercase;
  margin-bottom: 8px;
}

.lesson-sim-launch-name {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.lesson-sim-launch-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.lesson-sim-launch-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  background: var(--accent-cyan);
  color: var(--bg-void);
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  white-space: nowrap;
  transition: all var(--dur-fast) ease;
  border: none;
  cursor: pointer;
  font-family: var(--font-sans);
}

.lesson-sim-launch-btn:hover {
  background: #33e0ff;
  box-shadow: var(--glow-info);
  transform: translateY(-2px);
}

.lesson-sim-launch-btn svg { transition: transform var(--dur-fast) ease; }
.lesson-sim-launch-btn:hover svg { transform: translateX(4px); }

/* ──────────────────────────────────────────
   RELATED CONCEPTS PANEL
   ────────────────────────────────────────── */
.lesson-related {
  margin: 48px 0;
}

.lesson-related-title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 16px;
}

.lesson-related-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.lesson-related-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  background: var(--bg-surface);
  border: 1px solid var(--border-soft);
  border-radius: 100px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--dur-fast) ease;
  text-decoration: none;
}

.lesson-related-tag:hover {
  background: rgba(0, 212, 255, 0.08);
  border-color: var(--border-accent);
  color: var(--accent-cyan);
}

.lesson-related-tag-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-cyan);
  opacity: 0.5;
  transition: opacity var(--dur-fast) ease;
}

.lesson-related-tag:hover .lesson-related-tag-dot { opacity: 1; }

/* ──────────────────────────────────────────
   PREV / NEXT LESSON NAVIGATION
   ────────────────────────────────────────── */
.lesson-continue {
  margin-top: 80px;
  padding-top: 40px;
  border-top: 1px solid var(--border-subtle);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.lesson-continue-btn {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 20px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--dur-fast) ease;
  text-decoration: none;
}

.lesson-continue-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-accent);
}

.lesson-continue-btn.next { text-align: right; }

.lesson-continue-btn .direction {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.lesson-continue-btn .lesson-name {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.lesson-continue-btn .lesson-desc {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ──────────────────────────────────────────
   GUIDED MODE OVERLAY
   ────────────────────────────────────────── */
.guided-mode-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 72px;
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(20px, 5vw, 60px);
  z-index: 500;
  transform: translateY(100%);
  transition: transform var(--dur-base) var(--ease-smooth);
}

.guided-mode-bar.active { transform: translateY(0); }

.guided-mode-prompt {
  display: flex;
  align-items: center;
  gap: 12px;
}

.guided-mode-step-indicator {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.1);
  padding: 4px 10px;
  border-radius: 100px;
  border: 1px solid rgba(0, 212, 255, 0.2);
}

.guided-mode-instruction {
  font-size: 0.9rem;
  color: var(--text-secondary);
  max-width: 400px;
}

.guided-mode-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.guided-mode-skip {
  font-size: 0.8rem;
  color: var(--text-muted);
  cursor: pointer;
  transition: color var(--dur-fast) ease;
}
.guided-mode-skip:hover { color: var(--text-secondary); }

.guided-mode-next {
  padding: 10px 20px;
  background: var(--accent-cyan);
  color: var(--bg-void);
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all var(--dur-fast) ease;
  border: none;
  font-family: var(--font-sans);
}

.guided-mode-next:hover {
  background: #33e0ff;
  box-shadow: var(--glow-info);
}

/* ──────────────────────────────────────────
   LEARN HUB — Index Page
   ────────────────────────────────────────── */
.learn-hub {
  padding: calc(var(--nav-height) + 60px) var(--section-pad-x) 100px;
}

.learn-hub-header {
  margin-bottom: 64px;
}

.learn-hub-section-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-cyan);
  margin-bottom: 16px;
}

.learn-hub-title {
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: 20px;
}

.learn-hub-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 560px;
  line-height: 1.7;
}

/* Lesson Cards Grid */
.learn-hub-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
  margin-bottom: 60px;
}

.lesson-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 28px;
  cursor: pointer;
  transition: all var(--dur-base) var(--ease-smooth);
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow: hidden;
}

.lesson-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-indigo));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--dur-base) var(--ease-smooth);
}

.lesson-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-accent);
  transform: translateY(-4px);
  box-shadow: 0 12px 36px rgba(0, 0, 0, 0.4);
}

.lesson-card:hover::before { transform: scaleX(1); }

.lesson-card-number {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
}

.lesson-card-icon {
  font-size: 2rem;
  line-height: 1;
}

.lesson-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.lesson-card-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
  flex: 1;
}

.lesson-card-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 8px;
}

.lesson-card-status {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
}

.lesson-card-status-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
}

.status-not-started .lesson-card-status-dot { background: var(--text-muted); }
.status-not-started .lesson-card-status-text { color: var(--text-muted); }

.status-reading .lesson-card-status-dot { background: var(--color-warning); box-shadow: 0 0 6px rgba(255, 184, 48, 0.6); }
.status-reading .lesson-card-status-text { color: var(--color-warning); }

.status-completed .lesson-card-status-dot { background: var(--color-success); box-shadow: 0 0 6px rgba(0, 255, 157, 0.6); }
.status-completed .lesson-card-status-text { color: var(--color-success); }
.status-completed .lesson-card { border-color: rgba(0, 255, 157, 0.15); }

.lesson-card-duration {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Featured / First Lesson Card */
.lesson-card--featured {
  grid-column: span 2;
  flex-direction: row;
  align-items: center;
  gap: 40px;
  padding: 40px;
}

@media (max-width: 640px) { .lesson-card--featured { grid-column: span 1; flex-direction: column; } }

.lesson-card--featured .lesson-card-icon { font-size: 3.5rem; }

/* ──────────────────────────────────────────
   QUANTUM ROADMAP TAB
   ────────────────────────────────────────── */
.roadmap-page {
  padding: calc(var(--nav-height) + 60px) var(--section-pad-x) 100px;
}

.roadmap-header { margin-bottom: 56px; }

.roadmap-canvas-wrapper {
  position: relative;
  background: var(--bg-deep);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-xl);
  overflow: hidden;
  min-height: 600px;
}

#roadmap-canvas {
  display: block;
  width: 100%;
  cursor: grab;
}

#roadmap-canvas:active { cursor: grabbing; }

.roadmap-legend {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
  margin-top: 24px;
}

.roadmap-legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.roadmap-legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

/* ──────────────────────────────────────────
   GUIDED MODE TOGGLE (floating)
   ────────────────────────────────────────── */
.guided-mode-toggle {
  position: fixed;
  bottom: 92px;
  right: 24px;
  z-index: 400;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 18px;
  background: var(--bg-glass);
  backdrop-filter: blur(16px);
  border: 1px solid var(--border-soft);
  border-radius: 100px;
  cursor: pointer;
  font-size: 0.8rem;
  color: var(--text-secondary);
  transition: all var(--dur-fast) ease;
  box-shadow: 0 4px 20px rgba(0,0,0,0.4);
  opacity: 0;
  pointer-events: none;
}

.guided-mode-toggle.visible { opacity: 1; pointer-events: auto; }
.guided-mode-toggle.on { background: rgba(0, 212, 255, 0.1); border-color: var(--border-accent); color: var(--accent-cyan); }

/* ──────────────────────────────────────────
   SCROLL STORYTELLING — parallax sections
   ────────────────────────────────────────── */
.lesson-parallax-bg {
  position: relative;
  overflow: hidden;
}

.lesson-parallax-bg-element {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  pointer-events: none;
  opacity: 0.12;
  will-change: transform;
}

/* ──────────────────────────────────────────
   EXPANDABLE EXPLANATION
   ────────────────────────────────────────── */
.lesson-expandable {
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin: 24px 0;
}

.lesson-expandable-trigger {
  width: 100%;
  padding: 18px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-surface);
  border: none;
  color: var(--text-primary);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: background var(--dur-fast) ease;
  text-align: left;
}

.lesson-expandable-trigger:hover { background: var(--bg-card); }

.lesson-expandable-arrow {
  transition: transform var(--dur-fast) var(--ease-smooth);
  color: var(--text-muted);
  flex-shrink: 0;
}

.lesson-expandable.open .lesson-expandable-arrow { transform: rotate(180deg); }

.lesson-expandable-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s var(--ease-smooth);
}

.lesson-expandable.open .lesson-expandable-body { max-height: 1000px; }

.lesson-expandable-content {
  padding: 24px;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.95rem;
  line-height: 1.75;
  color: var(--text-secondary);
}

/* ──────────────────────────────────────────
   INTERACTIVE SLIDER WIDGET
   ────────────────────────────────────────── */
.lesson-slider-widget {
  margin: 40px 0;
  padding: 32px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
}

.lesson-slider-widget label {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.lesson-slider-widget label span {
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-weight: 700;
}

.lesson-slider-widget input[type="range"] {
  width: 100%;
  appearance: none;
  height: 4px;
  background: var(--border-soft);
  border-radius: 2px;
  outline: none;
  margin-bottom: 24px;
}

.lesson-slider-widget input[type="range"]::-webkit-slider-thumb {
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-cyan);
  cursor: pointer;
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.6);
  transition: box-shadow var(--dur-fast) ease;
}

.lesson-slider-widget input[type="range"]::-webkit-slider-thumb:hover {
  box-shadow: var(--glow-info);
}

.lesson-slider-output {
  text-align: center;
  padding: 20px;
  background: rgba(0, 0, 0, 0.3);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--text-primary);
  min-height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ──────────────────────────────────────────
   QUANTUM NUMBERS — address-system grid
   ────────────────────────────────────────── */
.qc-address-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  text-align: center;
}

.qc-address-cell {
  padding: 12px;
  border: 1px solid;
  border-radius: 10px;
}

@media (max-width: 560px) {
  .qc-address-grid { grid-template-columns: repeat(2, 1fr); }
}

/* KaTeX display equations must never clip on narrow screens */
.lesson-equation { overflow-x: auto; }
.lesson-equation .katex-display { overflow-x: auto; overflow-y: hidden; padding: 2px 0; }

/* ──────────────────────────────────────────
   RESPONSIVE
   ────────────────────────────────────────── */
@media (max-width: 1200px) {
  .lesson-section-nav { display: none; }
}

@media (max-width: 768px) {
  .lesson-hero { min-height: 55vh; padding-bottom: 48px; }
  .lesson-hero-title { font-size: clamp(2.2rem, 8vw, 3.5rem); }
  .lesson-sim-launch { flex-direction: column; gap: 20px; }
  .lesson-continue { grid-template-columns: 1fr; }
  .lesson-continue-btn.next { text-align: left; }
  .guided-mode-bar { padding: 0 20px; }
  .guided-mode-instruction { display: none; }
  .learn-hub-grid { grid-template-columns: 1fr; }
  .lesson-card--featured { grid-column: span 1; }
}

/* ──────────────────────────────────────────
   LEARN HUB — card progress + resume hint
   ────────────────────────────────────────── */
.lesson-card-progress {
  height: 3px;
  border-radius: 2px;
  background: var(--border-subtle);
  overflow: hidden;
  margin: 4px 0 12px;
}

.lesson-card-progress-fill {
  height: 100%;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-indigo));
  transition: width 0.5s var(--ease-smooth);
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.5);
}

.lesson-card-resume {
  color: var(--accent-cyan);
  font-weight: 700;
  margin-left: 8px;
}

/* ──────────────────────────────────────────
   RESUME CHIP — floating action on lesson page
   ────────────────────────────────────────── */
.lesson-resume-chip {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 450;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  background: linear-gradient(135deg, rgba(0, 212, 255, 0.15), rgba(124, 107, 255, 0.15));
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-accent);
  border-radius: 100px;
  color: var(--accent-cyan);
  font-size: 0.85rem;
  font-weight: 600;
  font-family: var(--font-sans);
  cursor: pointer;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.5), 0 0 20px rgba(0, 212, 255, 0.15);
  transition: all var(--dur-fast) ease;
}

.lesson-resume-chip:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.55), var(--glow-info);
}

/* ──────────────────────────────────────────
   SCAFFOLD / COMING SOON card
   ────────────────────────────────────────── */
.lesson-coming-soon {
  position: relative;
  overflow: hidden;
  padding: 40px;
  margin: 16px 0 40px;
  background: var(--bg-card);
  border: 1px dashed var(--border-accent);
  border-radius: var(--radius-lg);
}

.lesson-coming-soon-glow {
  position: absolute;
  top: -80px;
  right: -80px;
  width: 260px;
  height: 260px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 212, 255, 0.12), transparent 70%);
  pointer-events: none;
}

.lesson-coming-soon-badge {
  display: inline-block;
  padding: 4px 12px;
  margin-bottom: 16px;
  border-radius: 100px;
  background: rgba(255, 184, 48, 0.12);
  border: 1px solid rgba(255, 184, 48, 0.3);
  color: var(--color-warning);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.lesson-coming-soon h3 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.lesson-coming-soon p {
  font-size: 0.95rem;
  line-height: 1.75;
  color: var(--text-secondary);
  max-width: 560px;
  margin-bottom: 20px;
}

.lesson-coming-soon-sections {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* ──────────────────────────────────────────
   FRAMEWORK DEMO SLIDER WIDGET
   ────────────────────────────────────────── */
.lesson-demo-widget {
  width: 100%;
}

.lesson-slider-row {
  margin-bottom: 18px;
}

.lesson-slider-row label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 10px;
}

.lesson-slider-val {
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.85rem;
}

.lesson-slider-row input[type="range"] {
  width: 100%;
  appearance: none;
  height: 4px;
  background: var(--border-soft);
  border-radius: 2px;
  outline: none;
}

.lesson-slider-row input[type="range"]::-webkit-slider-thumb {
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-cyan);
  cursor: pointer;
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.6);
  transition: box-shadow var(--dur-fast) ease;
}

.lesson-slider-row input[type="range"]::-webkit-slider-thumb:hover {
  box-shadow: var(--glow-info);
}

.lesson-slider-row input[type="range"]::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-cyan);
  cursor: pointer;
  border: none;
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.6);
}

.lesson-demo-body .lesson-slider-output {
  margin-top: 8px;
}

/* ──────────────────────────────────────────
   FRAMEWORK DEMO CANVAS + RESULT
   (drawn by lesson-content.js onChange handlers)
   ────────────────────────────────────────── */
.qc-demo-canvas {
  display: block;
  width: 100%;
  max-width: 640px;
  height: auto;
  margin: 0 auto 8px;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
}

.qc-demo-result {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  line-height: 1.7;
  color: var(--text-secondary);
  text-align: left;
  max-width: 640px;
  margin: 0 auto;
}

.qc-demo-result strong { color: var(--text-primary); }

/* Tables inside demo results — never clipped, scroll on small screens */
.qc-demo-result table {
  width: 100%;
  max-width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-top: 8px;
}

.qc-demo-result table th,
.qc-demo-result table td {
  padding: 6px 12px;
  text-align: center;
  white-space: nowrap;
  border-bottom: 1px solid var(--border-subtle);
}

.qc-demo-result table th {
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

/* Scroll wrapper injected by the quantum-numbers demo */
.qc-demo-table-wrap {
  width: 100%;
  max-width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: var(--radius-sm);
}


/* ──────────────────────────────────────────
   DEFINITION CARD (framework)
   ────────────────────────────────────────── */
.lesson-definition-card {
  margin: 28px 0;
}

/* ──────────────────────────────────────────
   REFERENCES & MEDIA PLACEHOLDERS (future)
   ────────────────────────────────────────── */
.lesson-reference-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 12px;
}

.lesson-reference-list li {
  font-size: 0.9rem;
  color: var(--text-secondary);
  padding-left: 18px;
  position: relative;
}

.lesson-reference-list li::before {
  content: '↗';
  position: absolute;
  left: 0;
  color: var(--accent-cyan);
  font-size: 0.7rem;
  top: 4px;
}

.lesson-media-placeholder {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 28px 32px;
  margin: 28px 0;
  background: var(--bg-card);
  border: 1px dashed var(--border-soft);
  border-radius: var(--radius-md);
}

.lesson-media-icon {
  font-size: 1.8rem;
  flex-shrink: 0;
}

.lesson-media-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.lesson-media-note {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ──────────────────────────────────────────
   ROADMAP — tooltip + keyboard focus
   ────────────────────────────────────────── */
.roadmap-canvas-wrapper { position: relative; }

.roadmap-tooltip {
  position: absolute;
  top: 16px;
  left: 16px;
  max-width: 280px;
  display: flex;
  gap: 14px;
  padding: 14px 18px;
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5);
  opacity: 0;
  transform: translateY(-6px);
  transition: opacity var(--dur-fast) ease, transform var(--dur-fast) ease;
  pointer-events: none;
  z-index: 5;
}

.roadmap-tooltip.visible {
  opacity: 1;
  transform: translateY(0);
}

.roadmap-tooltip-icon {
  font-size: 1.6rem;
  line-height: 1;
  flex-shrink: 0;
}

.roadmap-tooltip-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.roadmap-tooltip-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 6px;
}

.roadmap-tooltip-status {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 100px;
  border: 1px solid;
}

.roadmap-tooltip-status.st-not-started { color: var(--text-muted); border-color: var(--border-soft); }
.roadmap-tooltip-status.st-reading { color: var(--color-warning); border-color: rgba(255, 184, 48, 0.4); }
.roadmap-tooltip-status.st-completed { color: var(--color-success); border-color: rgba(0, 255, 157, 0.4); }

.roadmap-tooltip-conns {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.roadmap-tooltip-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
}

#roadmap-canvas:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: -2px;
  border-radius: var(--radius-xl);
}

/* ──────────────────────────────────────────
   LAB → LESSON CHIP (Learn ↔ Explore)
   ────────────────────────────────────────── */
.lab-lesson-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  padding: 8px 16px;
  background: rgba(124, 107, 255, 0.1);
  border: 1px solid rgba(124, 107, 255, 0.3);
  border-radius: 100px;
  color: var(--accent-indigo);
  font-size: 0.8rem;
  font-weight: 600;
  text-decoration: none;
  transition: all var(--dur-fast) ease;
  width: fit-content;
}

.lab-lesson-chip:hover {
  background: rgba(124, 107, 255, 0.2);
  border-color: var(--accent-indigo);
  box-shadow: 0 0 16px rgba(124, 107, 255, 0.25);
  transform: translateY(-1px);
}

.lab-lesson-chip-arrow {
  transition: transform var(--dur-fast) ease;
}

.lab-lesson-chip:hover .lab-lesson-chip-arrow { transform: translateX(3px); }

/* ──────────────────────────────────────────
   KEYBOARD ACCESSIBILITY — focus states
   ────────────────────────────────────────── */
.lesson-section-nav-dot:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 3px;
}

.lesson-expandable-trigger:focus-visible,
.lesson-sim-launch-btn:focus-visible,
.lesson-continue-btn:focus-visible,
.lesson-related-tag:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 2px;
}

.guided-mode-toggle:focus-visible,
.guided-mode-next:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 2px;
}

/* ──────────────────────────────────────────
   RESPONSIVE — new components
   ────────────────────────────────────────── */
@media (max-width: 768px) {
  .lesson-coming-soon { padding: 28px 24px; }
  .lesson-resume-chip { right: 16px; bottom: 16px; font-size: 0.78rem; }
  .roadmap-tooltip { left: 10px; top: 10px; max-width: 230px; }
}

@media (prefers-reduced-motion: reduce) {
  .lesson-section, .lesson-timeline-event {
    opacity: 1 !important;
    transform: none !important;
    transition: none !important;
  }
  .lesson-card-progress-fill,
  .lesson-resume-chip,
  .roadmap-tooltip {
    transition: none !important;
  }
  .lesson-resume-chip:hover,
  .lab-lesson-chip:hover {
    transform: none;
  }
}