:root {
  --bg: #ffffff;
  --fg: #111111;
  --muted: #5f6368;
  --line: #d7d7d7;
  --soft: #f5f5f5;
  --blue: #dceaf7;
  --green: #e3f1e5;
  --orange: #f8e7d7;
  --brand-green: #25864f;
  --brand-soft: #eef7f1;
  --panel-left: 300px;
  --panel-right: 390px;
  --font: "Noto Sans TC", "Microsoft JhengHei", "PingFang TC", "Helvetica Neue", Arial, sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  font-family: var(--font);
  color: var(--fg);
  background: var(--bg);
  overflow-x: hidden;
}

button,
input {
  font: inherit;
}

button {
  min-height: 36px;
  border: 1px solid var(--fg);
  border-radius: 4px;
  background: #fff;
  color: var(--fg);
  padding: 7px 10px;
  cursor: pointer;
}

button:hover,
button:focus-visible {
  background: var(--fg);
  color: #fff;
}

.app-shell {
  display: grid;
  grid-template-columns: var(--panel-left) minmax(0, 1fr) var(--panel-right);
  min-height: 100vh;
}

.left-panel,
.right-panel {
  height: 100vh;
  overflow: auto;
  border-right: 1px solid var(--line);
  background: #fff;
}

.right-panel {
  border-right: 0;
  border-left: 1px solid var(--line);
}

.course-meta {
  padding: 22px 20px 18px;
  border-bottom: 1px solid var(--fg);
}

.course-logo {
  display: block;
  width: 176px;
  max-width: 100%;
  height: auto;
  margin: 0 0 18px;
}

.course-meta p {
  margin: 0 0 8px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.course-meta h1 {
  margin: 0 0 10px;
  font-size: 24px;
  line-height: 1.25;
  letter-spacing: 0;
}

.course-meta span {
  display: block;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.5;
}

.search-box {
  padding: 14px 16px;
  border-bottom: 1px solid var(--line);
}

.brand-block {
  padding: 24px 22px 18px;
  border-bottom: 1px solid var(--fg);
}

.eyebrow {
  margin: 0 0 18px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.brand-block h1 {
  margin: 0 0 12px;
  font-size: 25px;
  line-height: 1.22;
  letter-spacing: 0;
}

.brand-block p:last-child {
  margin: 0;
  color: var(--muted);
  line-height: 1.5;
}

.nav-tools {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 8px;
  padding: 14px;
  border-bottom: 1px solid var(--line);
}

.icon-button {
  padding: 0;
  font-size: 17px;
}

#pageSearch {
  min-height: 36px;
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0 10px;
}

.page-nav {
  padding: 10px 0 28px;
}

.nav-section {
  padding: 12px 16px 6px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.nav-item {
  width: 100%;
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 8px;
  border: 0;
  border-radius: 0;
  border-top: 1px solid var(--line);
  text-align: left;
  padding: 12px 16px;
  background: #fff;
}

.nav-item:hover,
.nav-item:focus-visible,
.nav-item.active {
  background: var(--soft);
  color: var(--fg);
}

.nav-number {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
}

.nav-title {
  font-weight: 700;
  line-height: 1.3;
}

.nav-summary {
  grid-column: 2;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.45;
}

.center-panel {
  min-width: 0;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  height: 100vh;
  background: #fafafa;
}

.topbar {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  background: #fff;
}

.topbar p,
.topbar h2 {
  margin: 0;
}

.topbar p {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
}

.topbar h2 {
  margin-top: 3px;
  font-size: 22px;
  line-height: 1.25;
}

.visual-stage {
  display: grid;
  place-items: center;
  min-height: 0;
  padding: 24px;
}

.image-frame-wrap {
  position: relative;
  width: min(100%, 1160px);
  aspect-ratio: 16 / 9;
}

.visual-stage img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
  background: #fff;
  border: 1px solid var(--line);
}

.image-hotspots {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.image-hotspot {
  position: absolute;
  display: block;
  border: 2px solid transparent;
  border-radius: 14px;
  pointer-events: auto;
  cursor: pointer;
}

.image-hotspot:hover,
.image-hotspot:focus-visible {
  border-color: #9f3a39;
  background: rgba(159, 58, 57, 0.08);
  outline: none;
}

.control-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 12px 16px;
  border-top: 1px solid var(--line);
  background: #fff;
}

.control-bar button,
.topbar button {
  border-color: var(--line);
}

.control-bar button:hover,
.control-bar button:focus-visible,
.topbar button:hover,
.topbar button:focus-visible {
  border-color: var(--fg);
}

.page-caption {
  padding: 16px 24px 20px;
  border-top: 1px solid var(--line);
  background: #fff;
}

.page-caption p {
  margin: 0 0 6px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
}

.page-caption h2 {
  margin: 0;
  font-size: 24px;
  line-height: 1.25;
}

.right-anchor-nav {
  position: sticky;
  top: 0;
  display: flex;
  gap: 8px;
  padding: 12px;
  border-bottom: 1px solid var(--line);
  background: #fff;
  z-index: 2;
}

.right-anchor-nav a {
  color: var(--fg);
  text-decoration: none;
  border-bottom: 1px solid currentColor;
  font-size: 13px;
}

.detail-tabs {
  position: sticky;
  top: 0;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
  padding: 12px;
  border-bottom: 1px solid var(--line);
  background: #fff;
  z-index: 2;
}

.detail-tabs button {
  display: grid;
  place-items: center;
  min-height: 34px;
  border: 1px solid var(--line);
  border-radius: 4px;
  color: var(--fg);
  text-decoration: none;
  font-size: 13px;
  line-height: 1.2;
  background: var(--soft);
  padding: 0 8px;
}

.detail-tabs button:hover,
.detail-tabs button:focus-visible,
.detail-tabs button.active {
  border-color: var(--fg);
  background: #fff;
  color: var(--fg);
}

#pageDetail {
  padding: 22px;
}

#pageDetail h3 {
  margin: 28px 0 12px;
  padding: 9px 12px;
  border-left: 4px solid var(--brand-green);
  background: var(--brand-soft);
  font-size: 17px;
  line-height: 1.35;
  scroll-margin-top: 72px;
}

#pageDetail h3:first-child {
  margin-top: 0;
}

#pageDetail p,
#pageDetail li {
  font-size: 15px;
  line-height: 1.7;
}

#pageDetail ul,
#pageDetail ol {
  padding-left: 1.2em;
}

.prompt-card {
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 16px;
  margin: 16px 0;
  background: #fff;
}

.prompt-card h3 {
  margin-top: 0 !important;
  border-left-color: var(--fg) !important;
  background: var(--soft) !important;
}

.prompt-card pre {
  white-space: pre-wrap;
  word-break: break-word;
  overflow: auto;
  padding: 12px;
  border: 1px solid var(--line);
  background: var(--soft);
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.6;
}

.resource-list {
  display: grid;
  gap: 10px;
  padding-left: 0 !important;
  list-style: none;
}

.resource-list li {
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  min-width: 0;
  overflow-wrap: anywhere;
}

.resource-list a {
  color: var(--fg);
  font-weight: 700;
  text-decoration: none;
  border-bottom: 1px solid currentColor;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.resource-list p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 13px !important;
  line-height: 1.55 !important;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 20px;
  transform: translateX(-50%);
  padding: 10px 14px;
  border: 1px solid var(--fg);
  background: #fff;
  opacity: 0;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
}

.image-lightbox {
  position: fixed;
  inset: 0;
  display: none;
  grid-template-rows: auto minmax(0, 1fr);
  gap: 12px;
  padding: 16px;
  background: rgba(255, 255, 255, 0.98);
  z-index: 20;
}

.image-lightbox.open {
  display: grid;
}

.lightbox-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-width: 0;
}

.lightbox-toolbar span {
  font-weight: 700;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.image-lightbox img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border: 1px solid var(--line);
  background: #fff;
}

.nav-collapsed,
.left-collapsed {
  --panel-left: 68px;
}

.nav-collapsed .course-meta h1,
.nav-collapsed .course-meta p,
.nav-collapsed .course-meta span,
.nav-collapsed #pageSearch,
.nav-collapsed .nav-title,
.nav-collapsed .nav-summary,
.nav-collapsed .nav-section,
.left-collapsed .brand-block h1,
.left-collapsed .brand-block p:last-child,
.left-collapsed #pageSearch,
.left-collapsed .nav-title,
.left-collapsed .nav-summary,
.left-collapsed .nav-section {
  display: none;
}

.nav-collapsed .course-logo {
  width: 36px;
  margin: 0 auto;
}

.nav-collapsed .search-box {
  display: none;
}

.left-collapsed .nav-tools {
  grid-template-columns: 40px;
}

.detail-collapsed,
.right-collapsed {
  --panel-right: 0px;
}

.detail-collapsed .right-panel,
.right-collapsed .right-panel {
  display: none;
}

@media (max-width: 1100px) {
  .app-shell {
    grid-template-columns: 1fr;
    max-width: 100vw;
    overflow-x: hidden;
  }

  .left-panel {
    display: none;
  }

  .mobile-nav-open .left-panel {
    display: block;
  }

  .left-panel,
  .right-panel,
  .center-panel {
    height: auto;
    max-width: 100vw;
    overflow-x: hidden;
  }

  .left-panel,
  .right-panel {
    border: 0;
    border-bottom: 1px solid var(--line);
  }

  .center-panel {
    min-height: 70vh;
    order: 1;
  }

  .left-panel {
    order: 2;
  }

  .mobile-nav-open .left-panel {
    order: 0;
  }

  .mobile-nav-open .course-meta {
    display: grid;
    grid-template-columns: 84px minmax(0, 1fr);
    gap: 4px 12px;
    padding: 12px 16px;
    align-items: center;
  }

  .mobile-nav-open .course-logo {
    grid-row: 1 / span 3;
    width: 78px;
    margin: 0;
  }

  .mobile-nav-open .course-meta p {
    margin: 0;
    font-size: 11px;
  }

  .mobile-nav-open .course-meta h1 {
    margin: 0;
    font-size: 18px;
  }

  .mobile-nav-open .course-meta span {
    font-size: 13px;
  }

  .right-panel {
    order: 3;
  }

  .page-nav {
    display: none;
  }

  .mobile-nav-open .page-nav {
    display: block;
    max-height: 44vh;
    overflow: auto;
    border-bottom: 1px solid var(--line);
  }

  .visual-stage {
    padding: 14px;
    overflow-x: hidden;
  }

  .image-frame-wrap {
    width: calc(100vw - 28px);
    max-width: calc(100vw - 28px);
  }

  .left-collapsed #pageSearch,
  .nav-collapsed #pageSearch,
  .nav-collapsed .course-meta,
  .left-collapsed .brand-block {
    display: none;
  }

  .nav-collapsed .page-nav,
  .left-collapsed .page-nav {
    display: none;
  }

  .mobile-nav-open.nav-collapsed .page-nav {
    display: block;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    scroll-behavior: auto !important;
  }
}

@media (max-width: 520px) {
  .app-shell,
  .left-panel,
  .right-panel,
  .center-panel {
    width: min(100vw, 390px);
    max-width: min(100vw, 390px);
  }

  .topbar {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    width: min(100vw, 390px);
    max-width: min(100vw, 390px);
    overflow-x: hidden;
  }

  .topbar button {
    width: 100%;
    min-width: 0;
    white-space: normal;
    overflow-wrap: anywhere;
    line-height: 1.25;
    padding: 8px 6px;
  }

  .image-frame-wrap {
    width: calc(min(100vw, 390px) - 28px);
    max-width: calc(min(100vw, 390px) - 28px);
  }
}