/* ========================================
   LearnAI — chapter deck navigator + waypoint rail
   Replaces the accordion table of contents. Chapter content
   (timeline map, lessons, buttons, images) is untouched.
   ======================================== */

/* Accent palette shared by cards, waypoints, and chapter heads.
   Mirrors the transit-map era colors. */
[data-accent="history"] {
  --card-accent: #d8942e;
  --card-accent-strong: #8b5a12;
  --card-accent-soft: rgba(216, 148, 46, 0.16);
  --card-surface: #fff6e6;
  --card-surface-deep: #f7e4be;
}

[data-accent="works"] {
  --card-accent: #368de0;
  --card-accent-strong: #075da9;
  --card-accent-soft: rgba(54, 141, 224, 0.14);
  --card-surface: #edf7ff;
  --card-surface-deep: #cee7fa;
}

[data-accent="agents"] {
  --card-accent: #26a77c;
  --card-accent-strong: #0b7454;
  --card-accent-soft: rgba(38, 167, 124, 0.14);
  --card-surface: #ecfaf5;
  --card-surface-deep: #caeddf;
}

/* ---------- Cover ---------- */
.learn-cover-sub {
  max-width: 560px;
  margin: 16px 0 0;
  color: var(--color-text-muted);
  font-size: 17px;
  line-height: 1.5;
}

/* ---------- Compact chapter choices ---------- */
.learn-deck {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 34px;
}

.learn-card {
  --learn-option-accent: #1877e6;
  --learn-option-ink: #0758b6;
  --learn-option-surface: #edf6ff;
  position: relative;
  display: flex;
  flex-direction: column;
  min-height: 214px;
  padding: 22px 24px 24px;
  overflow: hidden;
  isolation: isolate;
  border: 1px solid color-mix(in srgb, var(--learn-option-accent) 18%, #d8dde3);
  border-radius: 20px;
  background:
    radial-gradient(circle at 91% 8%, color-mix(in srgb, var(--learn-option-accent) 12%, transparent), transparent 34%),
    var(--learn-option-surface);
  color: #111820;
  text-decoration: none;
  box-shadow: 0 12px 30px rgba(31, 43, 55, 0.06);
  transition: transform 0.3s cubic-bezier(0.2, 0.7, 0.3, 1), box-shadow 0.3s ease, border-color 0.3s ease;
}

.learn-card[data-accent="works"] {
  --learn-option-accent: #23aa91;
  --learn-option-ink: #087661;
  --learn-option-surface: #eaf9f5;
}

.learn-card[data-accent="agents"] {
  --learn-option-accent: #7d57d8;
  --learn-option-ink: #5c36b5;
  --learn-option-surface: #f3efff;
}

.learn-card:hover,
.learn-card:focus-visible {
  transform: translateY(-4px);
  border-color: color-mix(in srgb, var(--learn-option-accent) 48%, #d8dde3);
  box-shadow:
    0 20px 42px rgba(31, 43, 55, 0.12),
    0 0 0 1px color-mix(in srgb, var(--learn-option-accent) 15%, transparent);
}

.learn-card:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--learn-option-accent) 48%, transparent);
  outline-offset: 3px;
}

.learn-card-num {
  color: var(--learn-option-ink);
  font-size: 10px;
  font-weight: 850;
  letter-spacing: 0.16em;
  line-height: 1;
}

.learn-card-icon {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  margin-top: 30px;
  border: 1px solid color-mix(in srgb, var(--learn-option-accent) 20%, transparent);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.72);
  color: var(--learn-option-ink);
  box-shadow: 0 8px 18px color-mix(in srgb, var(--learn-option-accent) 9%, transparent);
}

.learn-card-icon svg {
  width: 30px;
  height: 30px;
  overflow: visible;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.learn-card-copy {
  display: flex;
  flex-direction: column;
  gap: 5px;
  margin-top: auto;
  padding-top: 22px;
}

.learn-card-copy strong {
  color: #111820;
  font-size: clamp(21px, 2vw, 26px);
  font-weight: 810;
  letter-spacing: -0.035em;
  line-height: 1.05;
}

.learn-card-copy small {
  color: #53606d;
  font-size: 13px;
  line-height: 1.35;
}

.learn-card-arrow {
  position: absolute;
  top: 20px;
  right: 22px;
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--learn-option-accent) 11%, transparent);
  color: var(--learn-option-ink);
  font-size: 15px;
  font-weight: 800;
  transition: transform 0.25s ease, background-color 0.25s ease;
}

.learn-card:hover .learn-card-arrow,
.learn-card:focus-visible .learn-card-arrow {
  background: color-mix(in srgb, var(--learn-option-accent) 18%, transparent);
  transform: translateY(3px);
}

/* ---------- Chapters: always open ---------- */
.learn-chapters {
  gap: clamp(56px, 7vw, 96px);
  padding-top: clamp(40px, 5vw, 64px);
}

.learn-chapter {
  border-top: 0;
}

.learn-chapter-head {
  align-items: start;
  margin-bottom: 24px;
  padding-top: 22px;
  border-top: 2px solid color-mix(in srgb, var(--card-accent-strong, #111820) 55%, transparent);
  grid-template-columns: 72px minmax(0, 1fr);
}

.learn-chapter .learn-section-kicker {
  color: var(--card-accent-strong, var(--color-accent));
}

.learn-chapter .learn-chapter-number {
  color: color-mix(in srgb, var(--card-accent-strong, #111820) 34%, transparent);
}

/* ---------- Waypoint rail ---------- */
.learn-waypoints {
  position: fixed;
  left: 50%;
  bottom: 18px;
  z-index: 90;
  display: flex;
  gap: 4px;
  padding: 5px;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 999px;
  background: rgba(8, 21, 37, 0.9);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  box-shadow: 0 14px 38px rgba(8, 21, 37, 0.35);
  opacity: 0;
  pointer-events: none;
  transform: translate(-50%, 78px);
  transition: transform 0.35s cubic-bezier(0.2, 0.7, 0.3, 1), opacity 0.3s ease;
}

.learn-waypoints.is-visible {
  opacity: 1;
  pointer-events: auto;
  transform: translate(-50%, 0);
}

.learn-waypoints a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 15px;
  border-radius: 999px;
  color: rgba(238, 244, 250, 0.68);
  font-size: 12.5px;
  font-weight: 750;
  text-decoration: none;
  white-space: nowrap;
  transition: background 0.25s ease, color 0.25s ease;
}

.learn-waypoints a:hover {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.07);
}

.learn-waypoints a.is-active {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.12);
}

.learn-waypoints .wp-dot {
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--card-accent);
  opacity: 0.65;
  transition: opacity 0.25s ease, box-shadow 0.25s ease;
}

.learn-waypoints a.is-active .wp-dot {
  opacity: 1;
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--card-accent) 30%, transparent);
}

.learn-waypoints a:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--card-accent) 55%, transparent);
  outline-offset: 2px;
}

/* ---------- Responsive ---------- */
@media (max-width: 980px) {
  .learn-deck {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .learn-card {
    display: grid;
    grid-template-columns: 28px 44px minmax(0, 1fr) 28px;
    align-items: center;
    gap: 14px;
    min-height: 0;
    padding: 18px 20px;
  }

  .learn-card-icon {
    width: 44px;
    height: 44px;
    margin-top: 0;
  }

  .learn-card-copy {
    margin-top: 0;
    padding-top: 0;
  }

  .learn-card-arrow {
    position: static;
    width: 28px;
    height: 28px;
  }
}

@media (max-width: 700px) {
  .learn-deck {
    margin-top: 26px;
  }

  .learn-card {
    grid-template-columns: 20px 40px minmax(0, 1fr) 26px;
    gap: 10px;
    padding: 15px 14px;
    border-radius: 16px;
  }

  .learn-card-icon {
    width: 40px;
    height: 40px;
    border-radius: 12px;
  }

  .learn-card-icon svg {
    width: 26px;
    height: 26px;
  }

  .learn-card-copy strong {
    font-size: 19px;
  }

  .learn-card-copy small {
    font-size: 11.5px;
  }

  .learn-chapter-head {
    grid-template-columns: 48px minmax(0, 1fr);
    gap: 10px;
  }

  .learn-waypoints {
    bottom: 12px;
    max-width: calc(100vw - 16px);
  }

  .learn-waypoints a {
    gap: 6px;
    padding: 8px 11px;
    font-size: 11px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .learn-card,
  .learn-card-arrow,
  .learn-waypoints {
    transition-duration: 0.01ms !important;
  }
}