:root {
  --bg: #f5f5f1;
  --card: #ffffff;
  --text: #111111;
  --muted: #4a4a4a;
  --line: #dcdcd6;
  --accent: #dededb;
  --accent-hover: #cfcfcb;
  --accent-ink: #181818;
  --glow: #efefeb;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
  overflow-x: hidden;
}

#course-detail-root {
  overflow-x: clip;
}

.font-title {
  font-family: "Space Grotesk", "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
}

.font-mono {
  font-family: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

.text-muted { color: var(--muted); }
.border-soft { border-color: var(--line); }

.btn-primary,
.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 0.375rem;
  font-weight: 600;
  transition: background-color .2s ease, color .2s ease, transform .2s ease;
}

.btn-primary {
  background: #181818;
  color: #f5f5f1;
}

.btn-secondary {
  background: var(--accent);
  color: #181818;
}

.btn-primary:hover,
.btn-secondary:hover {
  background: #111111;
  color: #fff;
  transform: translateY(-1px);
}

.course-hero {
  position: relative;
  overflow: hidden;
}

.course-grid {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(17,17,17,.08) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(17,17,17,.08) 1px, transparent 1px);
  background-size: 28px 28px;
  mask-image: linear-gradient(90deg, rgba(0,0,0,.9), rgba(0,0,0,.2));
  opacity: .7;
}

.course-orbit {
  position: absolute;
  right: clamp(1rem, 6vw, 5rem);
  top: 2rem;
  width: clamp(180px, 22vw, 280px);
  aspect-ratio: 1;
  border: 1px solid rgba(17,17,17,.16);
  border-radius: 999px;
  pointer-events: none;
}

.course-orbit::before,
.course-orbit::after {
  content: "";
  position: absolute;
  border-radius: inherit;
  border: 1px solid rgba(17,17,17,.12);
}

.course-orbit::before {
  inset: 18%;
}

.course-orbit::after {
  inset: 42%;
  background: #111;
  border: 0;
}

.course-shell {
  position: relative;
  z-index: 1;
  min-width: 0;
}

.course-kpi {
  border: 1px solid var(--line);
  background: rgba(255,255,255,.88);
  backdrop-filter: blur(2px);
}

.section-kicker {
  color: var(--muted);
  font-size: .75rem;
  letter-spacing: .18em;
  text-transform: uppercase;
}

.reveal-line {
  width: clamp(80px, 12vw, 140px);
  height: 2px;
  margin-top: .7rem;
  background: #181818;
  opacity: .85;
}

#overview,
#objectives,
#levels,
#skills {
  scroll-margin-top: calc(9rem + 50px);
}

.overview-card,
.skill-card,
.level-card,
.objective-card {
  border: 1px solid var(--line);
  background: #fff;
  max-width: 100%;
  min-width: 0;
  overflow: hidden;
  overflow-wrap: anywhere;
  word-break: normal;
}

.course-main-grid,
.course-content,
.course-section-grid,
.course-levels-grid,
.course-level-main,
.course-objectives-grid {
  min-width: 0;
}

.course-section-grid > *,
.course-levels-grid > *,
.course-objectives-grid > * {
  min-width: 0;
}

.course-objectives-grid {
  grid-template-columns: minmax(0, 1fr);
}

@media (min-width: 768px) {
  .course-objectives-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.overview-card {
  box-shadow: 0 18px 36px rgba(17,17,17,.05);
}

.objective-card {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity .45s ease, transform .45s ease, border-color .2s ease;
}

.objective-card.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.objective-card:hover,
.skill-card:hover {
  border-color: rgba(17,17,17,.28);
}

.level-tabs {
  display: flex;
  gap: .5rem;
  width: 100%;
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding-bottom: .35rem;
  scrollbar-width: thin;
  overscroll-behavior-x: contain;
}

.level-tab {
  flex: 0 0 auto;
  min-width: min(15rem, 76vw);
  max-width: min(18rem, 82vw);
  border: 1px solid var(--line);
  border-radius: .65rem;
  background: #fff;
  color: var(--muted);
  padding: .8rem 1rem;
  text-align: left;
  white-space: normal;
  overflow-wrap: anywhere;
  transition: background-color .2s ease, color .2s ease, border-color .2s ease;
}

.level-tab[aria-selected="true"] {
  background: #181818;
  border-color: #181818;
  color: #fff;
}

.level-tab span {
  display: block;
  font-size: .72rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  opacity: .8;
}

.level-panel {
  display: none;
}

.level-panel.is-active {
  display: block;
  animation: panelEnter .34s ease both;
}

@keyframes panelEnter {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.path-list {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  align-items: stretch;
}

.path-chip {
  display: inline-grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: center;
  gap: .65rem;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: .75rem;
  background: #fff;
  padding: .65rem .75rem;
  transition: border-color .2s ease, background-color .2s ease, transform .2s ease;
}

.path-chip:hover {
  border-color: rgba(17,17,17,.3);
  background: var(--glow);
  transform: translateY(-1px);
}

.path-index {
  width: 1.85rem;
  height: 1.85rem;
  border-radius: 999px;
  display: grid;
  place-items: center;
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
  font-size: .9rem;
}

.path-title {
  display: block;
  min-width: 0;
  font-size: .95rem;
  font-weight: 700;
  line-height: 1.25;
  overflow-wrap: anywhere;
}

.skill-card {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity .45s ease, transform .45s ease, border-color .2s ease;
}

.skill-card.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.sticky-toc {
  position: sticky;
  top: 5.5rem;
}

.toc-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border: 1px solid var(--line);
  border-radius: .75rem;
  background: rgba(255,255,255,.82);
  padding: .85rem 1rem;
  color: var(--muted);
  transition: border-color .2s ease, color .2s ease, background-color .2s ease;
}

.toc-link:hover {
  border-color: rgba(17,17,17,.32);
  color: var(--text);
  background: #fff;
}

@media (max-width: 1023px) {
  .sticky-toc {
    position: static;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    scroll-behavior: auto !important;
    transition: none !important;
  }

  .objective-card,
  .skill-card {
    opacity: 1;
    transform: none;
  }
}