:root {
  --bg: #0b1020;
  --panel: #12192b;
  --panel-2: #192238;
  --line-dark: #2c3752;
  --text-on-dark: #f4f7ff;
  --muted-on-dark: #9aa7c2;
  --paper: #f7f5ef;
  --paper-2: #eeebe2;
  --ink: #171a25;
  --ink-2: #444a5a;
  --muted: #747b8b;
  --line: #d8d3c8;
  --blue: #3665f3;
  --blue-dark: #2148bb;
  --blue-soft: #e7edff;
  --orange: #f25b35;
  --orange-soft: #ffebe5;
  --lime: #d7f36a;
  --lime-ink: #263000;
  --shadow: 0 1.5rem 4rem rgb(0 0 0 / 0.24);
  --font: "Microsoft YaHei UI", "Microsoft YaHei", system-ui, sans-serif;
  --mono: "Cascadia Code", "SFMono-Regular", Consolas, monospace;
}

* { box-sizing: border-box; }
html { background: var(--bg); scroll-behavior: smooth; }
body {
  min-width: 320px;
  min-height: 100dvh;
  margin: 0;
  overflow: hidden;
  background: var(--bg);
  color: var(--text-on-dark);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.6;
}

button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { color: inherit; }
a { color: inherit; }
h1, h2, h3, p { margin: 0; }
button:focus-visible, a:focus-visible, input:focus-visible, [tabindex]:focus-visible {
  outline: 3px solid var(--lime);
  outline-offset: 3px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: fixed;
  inset: 1rem auto auto 1rem;
  z-index: 1000;
  padding: 0.7rem 1rem;
  background: var(--lime);
  color: var(--lime-ink);
  transform: translateY(-180%);
}
.skip-link:focus { transform: translateY(0); }

.course-app {
  min-height: 100dvh;
  display: grid;
  grid-template-columns: 15.5rem minmax(0, 1fr);
  grid-template-rows: 4.8rem minmax(0, 1fr);
}

.app-header {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: minmax(18rem, 1fr) minmax(20rem, 34rem) minmax(18rem, 1fr);
  align-items: center;
  gap: 1.5rem;
  padding: 0 1.4rem;
  border-bottom: 1px solid var(--line-dark);
  background: var(--bg);
}

.brand {
  min-width: 0;
  display: inline-flex;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none;
}
.brand-mark {
  width: 2.45rem;
  height: 2.45rem;
  flex: 0 0 auto;
  display: grid;
  place-items: center;
  border-radius: 0.7rem;
  background: var(--lime);
  color: var(--lime-ink);
  font-family: var(--mono);
  font-size: 0.88rem;
  font-weight: 800;
}
.brand-copy { min-width: 0; display: grid; line-height: 1.2; }
.brand-copy strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 1rem; }
.brand-copy small { margin-top: 0.25rem; color: var(--muted-on-dark); font-size: 0.75rem; }

.header-status {
  min-width: 0;
  display: grid;
  grid-template-columns: auto minmax(4rem, 1fr) auto;
  align-items: center;
  gap: 0.8rem;
  color: var(--muted-on-dark);
  font-family: var(--mono);
  font-size: 0.75rem;
}
.progress-track { height: 4px; overflow: hidden; border-radius: 999px; background: var(--line-dark); }
.progress-track i { display: block; width: 0; height: 100%; background: var(--lime); transition: width 280ms ease; }

.header-actions { justify-self: end; display: flex; gap: 0.55rem; }
.control {
  min-height: 2.6rem;
  padding: 0 0.9rem;
  border: 1px solid var(--line-dark);
  border-radius: 0.7rem;
  background: var(--panel);
  cursor: pointer;
  font-size: 0.88rem;
  font-weight: 700;
}
.control:hover { border-color: var(--muted-on-dark); }
.control-primary { border-color: var(--blue); background: var(--blue); }
.control-primary:hover { border-color: var(--lime); }
.control kbd { margin-left: 0.45rem; }
kbd {
  padding: 0.12rem 0.38rem;
  border: 1px solid currentColor;
  border-radius: 0.3rem;
  font-family: var(--mono);
  font-size: 0.72em;
  font-weight: 500;
  white-space: nowrap;
}

.chapter-rail {
  min-height: 0;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  border-right: 1px solid var(--line-dark);
  background: var(--panel);
}
.rail-heading {
  padding: 1.25rem 1rem 0.9rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  color: var(--muted-on-dark);
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
}
.rail-heading button, .rail-footer button {
  border: 0;
  background: transparent;
  color: var(--text-on-dark);
  cursor: pointer;
  font-size: 0.82rem;
}
.chapter-rail nav { min-height: 0; overflow-y: auto; padding: 0 0.65rem 1rem; }
.chapter-link {
  width: 100%;
  min-height: 3.9rem;
  margin-bottom: 0.28rem;
  padding: 0.55rem 0.65rem;
  display: grid;
  grid-template-columns: 2rem minmax(0, 1fr);
  gap: 0.45rem;
  align-items: center;
  border: 1px solid transparent;
  border-radius: 0.75rem;
  background: transparent;
  color: var(--muted-on-dark);
  cursor: pointer;
  text-align: left;
}
.chapter-link:hover { background: var(--panel-2); color: var(--text-on-dark); }
.chapter-link.is-active { border-color: var(--blue); background: var(--blue); color: white; }
.chapter-link b {
  font-family: var(--mono);
  font-size: 0.78rem;
}
.chapter-link span { min-width: 0; display: grid; line-height: 1.25; }
.chapter-link strong { font-size: 0.88rem; }
.chapter-link small { margin-top: 0.25rem; overflow: hidden; color: inherit; opacity: 0.72; font-size: 0.68rem; text-overflow: ellipsis; white-space: nowrap; }
.rail-footer { padding: 1rem; border-top: 1px solid var(--line-dark); }
.rail-footer p { margin-bottom: 0.5rem; color: var(--muted-on-dark); font-family: var(--mono); font-size: 0.7rem; }
.rail-footer button { padding: 0; text-decoration: underline; text-underline-offset: 0.25rem; }

.workspace {
  min-width: 0;
  min-height: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 20rem;
  background: var(--bg);
}
.stage-wrap {
  min-width: 0;
  min-height: 0;
  padding: 1.15rem 1.2rem 1rem;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  gap: 0.7rem;
}
.stage-meta, .stage-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  color: var(--muted-on-dark);
  font-size: 0.78rem;
}
.stage-meta > div:first-child { min-width: 0; display: flex; align-items: baseline; gap: 0.8rem; }
.stage-meta span:first-child { color: var(--lime); font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.08em; }
.stage-meta b { overflow: hidden; color: var(--text-on-dark); text-overflow: ellipsis; white-space: nowrap; }
.stage-shortcuts { display: flex; gap: 0.9rem; }
.stage-shortcuts span { white-space: nowrap; }

.slide-stage {
  position: relative;
  min-width: 0;
  min-height: 32rem;
  max-height: calc(100dvh - 10.4rem);
  overflow: auto;
  border-radius: 1.3rem;
  background: var(--paper);
  color: var(--ink);
  box-shadow: var(--shadow);
}
.slide-stage::-webkit-scrollbar { width: 10px; }
.slide-stage::-webkit-scrollbar-thumb { border: 3px solid var(--paper); border-radius: 999px; background: var(--line); }

.overview-slide { min-height: 100%; padding: clamp(2rem, 4vw, 4.2rem); display: grid; align-content: center; }
.overview-top { display: grid; grid-template-columns: minmax(0, 0.95fr) minmax(18rem, 1.05fr); gap: clamp(2rem, 4vw, 5rem); align-items: end; }
.slide-kicker { color: var(--blue); font-family: var(--mono); font-size: 0.78rem; font-weight: 800; letter-spacing: 0.1em; }
.overview-top h1 { margin-top: 0.75rem; max-width: 9ch; font-size: clamp(3rem, 5.4vw, 6.4rem); letter-spacing: -0.07em; line-height: 0.98; }
.overview-thesis { padding-bottom: 0.3rem; }
.overview-thesis > p { max-width: 31rem; color: var(--ink-2); font-size: clamp(1.05rem, 1.5vw, 1.35rem); line-height: 1.7; }
.method-loop { margin-top: 1.5rem; display: grid; grid-template-columns: repeat(5, 1fr); border: 1px solid var(--line); border-radius: 0.9rem; overflow: hidden; }
.method-loop span { padding: 0.75rem 0.3rem; border-right: 1px solid var(--line); text-align: center; }
.method-loop span:last-child { border-right: 0; }
.method-loop b { display: block; color: var(--blue); font-size: 1.45rem; line-height: 1.1; }
.method-loop small { color: var(--muted); font-size: 0.7rem; }

.overview-map { margin-top: clamp(2rem, 4vw, 3.5rem); display: grid; grid-template-columns: repeat(9, minmax(0, 1fr)); gap: 0.55rem; }
.map-card {
  min-width: 0;
  min-height: 7.1rem;
  padding: 0.75rem;
  display: grid;
  align-content: space-between;
  border: 1px solid var(--line);
  border-radius: 0.85rem;
  background: transparent;
  color: var(--ink);
  cursor: pointer;
  text-align: left;
}
.map-card:hover { border-color: var(--blue); background: var(--blue-soft); transform: translateY(-2px); }
.map-card b { color: var(--blue); font-family: var(--mono); font-size: 0.72rem; }
.map-card strong { font-size: 0.86rem; line-height: 1.35; }
.overview-caption { margin-top: 1rem; display: flex; justify-content: space-between; gap: 1rem; color: var(--muted); font-size: 0.75rem; }

.chapter-slide { min-width: 0; min-height: 100%; padding: clamp(1.7rem, 3.5vw, 3.8rem); display: grid; grid-template-rows: auto minmax(0, 1fr); }
.chapter-slide-head { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 1.2rem; align-items: start; padding-bottom: 1.5rem; border-bottom: 1px solid var(--line); }
.chapter-number {
  width: 3.1rem;
  height: 3.1rem;
  display: grid;
  place-items: center;
  border-radius: 0.9rem;
  background: var(--blue);
  color: white;
  font-family: var(--mono);
  font-weight: 800;
}
.chapter-title { min-width: 0; }
.chapter-title h1 { overflow-wrap: anywhere; font-size: clamp(2.1rem, 3.8vw, 4.4rem); letter-spacing: -0.055em; line-height: 1.05; }
.chapter-title p { margin-top: 0.6rem; max-width: 56rem; color: var(--ink-2); font-size: clamp(1rem, 1.3vw, 1.2rem); }
.chapter-tag { padding: 0.35rem 0.6rem; border: 1px solid var(--line); border-radius: 999px; color: var(--muted); font-family: var(--mono); font-size: 0.68rem; white-space: nowrap; }

.chapter-slide-body { min-height: 0; padding-top: 1.5rem; display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(15rem, 0.75fr); gap: clamp(1.5rem, 3vw, 3rem); }
.chapter-slide-body > * { min-width: 0; }
.idea-list { margin: 0; padding: 0; display: grid; align-content: start; gap: 0.65rem; list-style: none; }
.idea-list li { display: grid; grid-template-columns: 2rem minmax(0, 1fr); gap: 0.65rem; align-items: start; color: var(--ink-2); font-size: clamp(0.96rem, 1.2vw, 1.1rem); line-height: 1.55; }
.idea-list li b { padding-top: 0.05rem; color: var(--blue); font-family: var(--mono); font-size: 0.75rem; }
.idea-list li:first-child { padding: 0.9rem; border-radius: 0.8rem; background: var(--blue-soft); color: var(--ink); }
.demo-card { align-self: start; padding: 1.25rem; border-radius: 1rem; background: var(--ink); color: white; }
.demo-card > span { color: var(--lime); font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.08em; }
.demo-card h2 { margin: 0.35rem 0 1rem; font-size: 1.45rem; }
.demo-card ol { margin: 0; padding: 0; display: grid; gap: 0.8rem; list-style: none; counter-reset: demo; }
.demo-card li { display: grid; grid-template-columns: 1.65rem minmax(0, 1fr); gap: 0.55rem; color: #dbe1ef; font-size: 0.9rem; line-height: 1.5; counter-increment: demo; }
.demo-card li::before { content: counter(demo); width: 1.65rem; height: 1.65rem; display: grid; place-items: center; border: 1px solid #54617d; border-radius: 50%; color: var(--lime); font-family: var(--mono); font-size: 0.7rem; }

.model-zone { min-width: 0; width: 100%; grid-column: 1 / -1; margin-top: 0.4rem; }
.model-table-wrap { width: 100%; max-width: 100%; overflow-x: auto; border: 1px solid var(--line); border-radius: 0.8rem; }
.model-table { width: 100%; min-width: 34rem; border-collapse: collapse; font-size: 0.82rem; font-variant-numeric: tabular-nums; }
.model-table th, .model-table td { padding: 0.65rem 0.75rem; border-bottom: 1px solid var(--line); text-align: left; white-space: nowrap; }
.model-table th { background: var(--paper-2); color: var(--ink); }
.model-table tr:last-child td { border-bottom: 0; }
.table-note { margin-top: 0.45rem; color: var(--muted); font-size: 0.72rem; }

.stage-footer { min-height: 2.7rem; }
.stage-footer p { font-family: var(--mono); font-size: 0.72rem; }
.nav-button {
  min-height: 2.45rem;
  padding: 0 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  border: 1px solid var(--line-dark);
  border-radius: 0.65rem;
  background: var(--panel);
  cursor: pointer;
  font-size: 0.82rem;
}
.nav-button:hover { border-color: var(--blue); }
.nav-button:disabled { opacity: 0.35; cursor: default; }

.speaker-panel { min-height: 0; display: grid; grid-template-rows: auto minmax(0, 1fr) auto; border-left: 1px solid var(--line-dark); background: var(--panel); }
.speaker-head { padding: 1.25rem; display: flex; justify-content: space-between; gap: 1rem; border-bottom: 1px solid var(--line-dark); }
.speaker-head span { color: var(--muted-on-dark); font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.08em; }
.speaker-head b { color: var(--lime); font-size: 0.75rem; }
.speaker-content { min-height: 0; overflow-y: auto; padding: 1.2rem; }
.speaker-section + .speaker-section { margin-top: 1.25rem; padding-top: 1.25rem; border-top: 1px solid var(--line-dark); }
.speaker-section > span { color: var(--muted-on-dark); font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.08em; }
.speaker-section h3 { margin: 0.4rem 0 0.65rem; font-size: 1rem; }
.speaker-section p { color: #c7d0e3; font-size: 0.88rem; line-height: 1.65; }
.speaker-prompt { padding: 0.9rem; border-radius: 0.8rem; background: var(--panel-2); }
.speaker-prompt p { color: #e2e7f2; }
.copy-button { width: 100%; min-height: 2.5rem; margin-top: 0.75rem; border: 1px solid var(--blue); border-radius: 0.65rem; background: transparent; color: #bdcaff; cursor: pointer; font-weight: 700; }
.copy-button:hover { background: var(--blue); color: white; }
.source-list { display: grid; gap: 0.45rem; }
.source-list a { color: #bdcaff; font-size: 0.78rem; text-underline-offset: 0.2rem; }
.speaker-foot { padding: 0.9rem 1.2rem; border-top: 1px solid var(--line-dark); color: var(--muted-on-dark); font-size: 0.72rem; }

dialog { color: inherit; }
dialog::backdrop { background: rgb(5 9 20 / 0.76); backdrop-filter: blur(5px); }
.command-dialog, .glossary-dialog {
  padding: 0;
  border: 1px solid var(--line-dark);
  border-radius: 1rem;
  background: var(--panel);
  color: var(--text-on-dark);
  box-shadow: var(--shadow);
}
.command-dialog { width: min(42rem, calc(100% - 2rem)); }
.command-field { padding: 1.2rem; border-bottom: 1px solid var(--line-dark); }
.command-field label { display: block; margin-bottom: 0.55rem; font-weight: 700; }
.command-field > div { min-height: 3.2rem; padding: 0 0.85rem; display: flex; align-items: center; gap: 0.65rem; border: 1px solid var(--line-dark); border-radius: 0.75rem; background: var(--bg); }
.command-field input { min-width: 0; flex: 1; border: 0; outline: 0; background: transparent; color: white; }
.command-field input::placeholder { color: var(--muted-on-dark); }
.command-results { max-height: 26rem; overflow-y: auto; padding: 0.55rem; }
.command-result { width: 100%; padding: 0.7rem; display: grid; grid-template-columns: 3rem minmax(0, 1fr); gap: 0.7rem; border: 1px solid transparent; border-radius: 0.65rem; background: transparent; color: var(--text-on-dark); cursor: pointer; text-align: left; }
.command-result.is-selected { border-color: var(--blue); background: var(--panel-2); }
.command-result > span { color: var(--lime); font-family: var(--mono); font-size: 0.68rem; }
.command-result strong { display: block; font-size: 0.9rem; }
.command-result small { display: block; margin-top: 0.2rem; color: var(--muted-on-dark); font-size: 0.75rem; }
.command-dialog > footer { padding: 0.65rem 1.2rem; display: flex; gap: 1.2rem; border-top: 1px solid var(--line-dark); color: var(--muted-on-dark); font-size: 0.72rem; }

.glossary-dialog { width: min(72rem, calc(100% - 2rem)); max-height: calc(100dvh - 2rem); }
.glossary-dialog header { padding: 1.4rem 1.6rem; display: flex; justify-content: space-between; align-items: start; border-bottom: 1px solid var(--line-dark); }
.glossary-dialog header span { color: var(--lime); font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.08em; }
.glossary-dialog h2 { margin-top: 0.35rem; font-size: 1.8rem; }
.glossary-dialog header button { width: 2.5rem; height: 2.5rem; border: 1px solid var(--line-dark); border-radius: 50%; background: transparent; cursor: pointer; font-size: 1.3rem; }
.glossary-dialog dl { margin: 0; padding: 1.4rem 1.6rem 2rem; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0; overflow-y: auto; }
.glossary-dialog dl > div { padding: 1rem; border-bottom: 1px solid var(--line-dark); }
.glossary-dialog dt { color: var(--lime); font-family: var(--mono); font-weight: 700; }
.glossary-dialog dd { margin: 0.35rem 0 0; color: #c7d0e3; font-size: 0.84rem; }

.print-book { display: none; }

body.is-presenting .course-app { grid-template-columns: 1fr; grid-template-rows: 4.3rem minmax(0, 1fr); }
body.is-presenting .chapter-rail, body.is-presenting .speaker-panel, body.is-presenting .stage-meta, body.is-presenting .stage-footer { display: none; }
body.is-presenting .app-header { grid-template-columns: 1fr auto; }
body.is-presenting .header-status { display: none; }
body.is-presenting .workspace { grid-template-columns: 1fr; }
body.is-presenting .stage-wrap { padding: 0.8rem; display: block; }
body.is-presenting .slide-stage { height: calc(100dvh - 5.9rem); max-height: none; border-radius: 0.9rem; }

@media (max-width: 1500px) {
  .overview-map { grid-template-columns: repeat(5, minmax(0, 1fr)); }
}

@media (max-width: 1180px) {
  .course-app { grid-template-columns: 13.5rem minmax(0, 1fr); }
  .workspace { grid-template-columns: minmax(0, 1fr) 17rem; }
  .app-header { grid-template-columns: minmax(16rem, 1fr) minmax(12rem, 22rem) auto; }
  .control kbd, .stage-shortcuts { display: none; }
}

@media (max-width: 900px) {
  body { overflow: auto; font-size: 16px; }
  .course-app { min-height: 100dvh; display: block; }
  .app-header { position: sticky; top: 0; z-index: 20; min-height: 4.3rem; grid-template-columns: minmax(0, 1fr) auto; padding: 0 0.8rem; }
  .header-status { display: none; }
  .header-actions .control-quiet { display: none; }
  .chapter-rail { max-width: 100vw; overflow: hidden; display: block; border-right: 0; border-bottom: 1px solid var(--line-dark); }
  .rail-heading, .rail-footer { display: none; }
  .chapter-rail nav { width: 100%; max-width: 100vw; display: flex; overflow-x: auto; overflow-y: hidden; padding: 0.55rem; }
  .chapter-link { min-width: 10rem; margin: 0 0.35rem 0 0; }
  .workspace { display: block; }
  .stage-wrap { padding: 0.7rem; }
  .slide-stage { min-height: 0; max-height: none; overflow: visible; }
  .overview-slide, .chapter-slide { min-height: 42rem; padding: 1.5rem; }
  .overview-top { grid-template-columns: 1fr; gap: 1.4rem; }
  .overview-top h1 { font-size: clamp(3rem, 15vw, 5rem); }
  .overview-map { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .map-card { min-height: 6rem; }
  .chapter-slide-head { grid-template-columns: auto minmax(0, 1fr); }
  .chapter-tag { display: none; }
  .chapter-slide-body { grid-template-columns: 1fr; }
  .chapter-slide-body { width: 100%; min-width: 0; }
  .speaker-panel { border: 0; border-top: 1px solid var(--line-dark); }
  .speaker-content { overflow: visible; }
  .glossary-dialog dl { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 560px) {
  .brand-copy small { display: none; }
  .brand-copy strong { font-size: 0.88rem; }
  .control-primary { padding: 0 0.7rem; }
  .stage-meta { display: none; }
  .stage-wrap { gap: 0.5rem; }
  .overview-slide, .chapter-slide { padding: 1.15rem; }
  .overview-top h1 { font-size: 3.2rem; }
  .overview-thesis > p { font-size: 1rem; }
  .method-loop small { display: none; }
  .method-loop span { padding: 0.55rem 0.2rem; }
  .overview-map { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .overview-caption { display: none; }
  .chapter-number { width: 2.6rem; height: 2.6rem; }
  .chapter-title h1 { font-size: 2.15rem; }
  .chapter-slide-head { gap: 0.7rem; }
  .idea-list li { grid-template-columns: 1.5rem minmax(0, 1fr); font-size: 0.96rem; }
  .stage-footer p { display: none; }
  .glossary-dialog dl { grid-template-columns: 1fr; }
}

/* PPT mode: one large idea, one strong visual, three memorable points. */
@media screen {
  .overview-slide {
    min-height: 100%;
    padding: clamp(2rem, 3.2vw, 4rem);
    display: grid;
    grid-template-rows: minmax(0, 1fr) auto;
    gap: 1.6rem;
    align-content: stretch;
  }

  .overview-hero {
    min-width: 0;
    display: grid;
    grid-template-columns: minmax(0, 0.86fr) minmax(22rem, 1.14fr);
    gap: clamp(2rem, 4vw, 5rem);
    align-items: center;
  }

  .overview-copy { min-width: 0; }
  .overview-copy h1 {
    margin-top: 0.9rem;
    max-width: 8ch;
    font-size: clamp(4.3rem, 6.2vw, 7.6rem);
    letter-spacing: -0.075em;
    line-height: 0.95;
  }
  .overview-copy > p {
    max-width: 24em;
    margin-top: 1.8rem;
    color: var(--ink-2);
    font-size: clamp(1.25rem, 1.7vw, 1.75rem);
    line-height: 1.6;
  }
  .overview-copy > strong {
    display: block;
    max-width: 26em;
    margin-top: 1rem;
    color: var(--blue);
    font-size: clamp(1rem, 1.25vw, 1.25rem);
    line-height: 1.6;
  }

  .atlas-overview {
    position: relative;
    width: min(100%, 38rem);
    aspect-ratio: 1;
    justify-self: center;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    overflow: hidden;
    border-radius: 1.15rem;
    background: var(--bg);
    box-shadow: 0 1.4rem 3rem rgb(14 20 40 / 0.24);
  }
  .atlas-overview > img { position: absolute; inset: 0; width: 100%; height: 100%; display: block; object-fit: cover; }
  .atlas-hotspot {
    position: relative;
    z-index: 1;
    padding: 0.55rem;
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    border: 1px solid rgb(255 255 255 / 0.12);
    background: transparent;
    color: white;
    cursor: pointer;
    text-align: left;
  }
  .atlas-hotspot:hover { border-color: var(--lime); background: rgb(7 12 28 / 0.34); }
  .atlas-hotspot b {
    width: 1.7rem;
    height: 1.7rem;
    display: grid;
    place-items: center;
    border-radius: 50%;
    background: var(--lime);
    color: var(--lime-ink);
    font-family: var(--mono);
    font-size: 0.72rem;
  }
  .atlas-hotspot span { padding: 0.18rem 0.4rem; border-radius: 0.3rem; background: rgb(7 12 28 / 0.72); font-size: 0.74rem; font-weight: 700; }
  .atlas-hotspot[data-chapter="1"] { grid-area: 1 / 1; }
  .atlas-hotspot[data-chapter="2"] { grid-area: 1 / 2; }
  .atlas-hotspot[data-chapter="3"] { grid-area: 1 / 3; }
  .atlas-hotspot[data-chapter="4"] { grid-area: 2 / 1; }
  .atlas-hotspot[data-chapter="5"] { grid-area: 2 / 2; }
  .atlas-hotspot[data-chapter="6"] { grid-area: 2 / 3; }
  .atlas-hotspot[data-chapter="7"] { grid-area: 3 / 1; }
  .atlas-hotspot[data-chapter="8"] { grid-area: 3 / 2; }
  .atlas-hotspot[data-chapter="9"] { grid-area: 3 / 3; }

  .overview-slide > .method-loop {
    margin: 0;
    min-height: 5.2rem;
    border-width: 2px;
    background: white;
  }
  .overview-slide > .method-loop span { display: grid; place-content: center; }
  .overview-slide > .method-loop b { font-size: clamp(1.65rem, 2.2vw, 2.35rem); }
  .overview-slide > .method-loop small { margin-top: 0.18rem; font-size: 0.78rem; }

  .chapter-slide {
    min-height: 100%;
    padding: clamp(2rem, 3.2vw, 4rem);
    display: grid;
    grid-template-rows: auto minmax(0, 1fr);
  }
  .chapter-slide-head {
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 1.2rem;
    padding-bottom: 1.25rem;
  }
  .chapter-number { width: 3.5rem; height: 3.5rem; font-size: 1.05rem; }
  .chapter-title > span { display: block; margin-bottom: 0.3rem; color: var(--blue); font-family: var(--mono); font-size: 0.75rem; font-weight: 800; letter-spacing: 0.08em; }
  .chapter-title h1 { font-size: clamp(3.2rem, 4.5vw, 5.5rem); }

  .chapter-ppt-body {
    min-width: 0;
    min-height: 0;
    padding-top: clamp(1.5rem, 2.5vw, 2.8rem);
    display: grid;
    grid-template-columns: minmax(0, 0.98fr) minmax(22rem, 1.02fr);
    gap: clamp(2rem, 4vw, 5rem);
    align-items: center;
  }
  .chapter-message { min-width: 0; display: grid; align-content: center; }
  .chapter-claim {
    max-width: 22em;
    color: var(--ink);
    font-size: clamp(1.55rem, 2vw, 2.15rem);
    font-weight: 700;
    letter-spacing: -0.025em;
    line-height: 1.45;
  }
  .big-points { margin: 1.8rem 0 0; padding: 0; display: grid; gap: 0.75rem; list-style: none; }
  .big-points li {
    min-height: 3.5rem;
    padding: 0.65rem 0.8rem;
    display: grid;
    grid-template-columns: 2.25rem minmax(0, 1fr);
    gap: 0.75rem;
    align-items: center;
    border: 1px solid var(--line);
    border-radius: 0.8rem;
    color: var(--ink-2);
    font-size: clamp(1.05rem, 1.25vw, 1.3rem);
    font-weight: 700;
  }
  .big-points li b { width: 2.25rem; height: 2.25rem; display: grid; place-items: center; border-radius: 0.65rem; background: var(--blue-soft); color: var(--blue); font-family: var(--mono); font-size: 0.78rem; }
  .live-demo-line { margin-top: 1.35rem; padding-top: 1rem; display: grid; grid-template-columns: auto minmax(0, 1fr); gap: 0.8rem; border-top: 2px solid var(--ink); align-items: baseline; }
  .live-demo-line span { color: var(--orange); font-family: var(--mono); font-size: 0.74rem; font-weight: 800; white-space: nowrap; }
  .live-demo-line b { color: var(--ink-2); font-size: 0.95rem; line-height: 1.55; }

  .atlas-cell {
    position: relative;
    width: min(100%, 37rem);
    aspect-ratio: 1;
    justify-self: center;
    overflow: hidden;
    margin: 0;
    border-radius: 1.35rem;
    background: var(--bg);
    box-shadow: 0 1.5rem 3rem rgb(14 20 40 / 0.26);
  }
  .atlas-cell img { position: absolute; width: 300%; height: 300%; max-width: none; object-fit: fill; }
  .atlas-cell-1 img { left: 0; top: 0; }
  .atlas-cell-2 img { left: -100%; top: 0; }
  .atlas-cell-3 img { left: -200%; top: 0; }
  .atlas-cell-4 img { left: 0; top: -100%; }
  .atlas-cell-5 img { left: -100%; top: -100%; }
  .atlas-cell-6 img { left: -200%; top: -100%; }
  .atlas-cell-7 img { left: 0; top: -200%; }
  .atlas-cell-8 img { left: -100%; top: -200%; }
  .atlas-cell-9 img { left: -200%; top: -200%; }

  .speaker-list { margin: 0.6rem 0 0; padding-left: 1.15rem; color: #c7d0e3; font-size: 0.82rem; line-height: 1.6; }
  .speaker-list li + li { margin-top: 0.45rem; }
  .speaker-models .model-table-wrap { max-height: 22rem; }
}

@media screen and (max-width: 1180px) {
  .overview-hero { grid-template-columns: minmax(0, 0.9fr) minmax(19rem, 1.1fr); gap: 2rem; }
  .atlas-overview { width: min(100%, 30rem); }
  .chapter-ppt-body { grid-template-columns: minmax(0, 1fr) minmax(19rem, 0.9fr); gap: 2rem; }
  .atlas-cell { width: min(100%, 29rem); }
}

@media screen and (max-width: 900px) {
  .overview-slide { min-height: 0; padding: 1.35rem; }
  .overview-hero { grid-template-columns: 1fr; }
  .overview-copy h1 { font-size: clamp(3.4rem, 14vw, 5rem); }
  .overview-copy > p { margin-top: 1rem; font-size: 1.12rem; }
  .overview-copy > strong { font-size: 0.95rem; }
  .atlas-overview { width: min(100%, 34rem); }
  .overview-slide > .method-loop { min-height: 4.4rem; }

  .chapter-slide { min-height: 0; padding: 1.35rem; }
  .chapter-slide-head { grid-template-columns: auto minmax(0, 1fr); }
  .chapter-title h1 { font-size: clamp(2.5rem, 10vw, 3.7rem); }
  .chapter-ppt-body { grid-template-columns: 1fr; gap: 1.6rem; }
  .chapter-claim { font-size: 1.45rem; }
  .big-points { margin-top: 1.25rem; }
  .big-points li { font-size: 1.02rem; }
  .atlas-cell { width: min(100%, 34rem); }
}

@media screen and (max-width: 560px) {
  .atlas-hotspot span { display: none; }
  .overview-slide > .method-loop small { display: none; }
  .chapter-number { width: 2.75rem; height: 2.75rem; }
  .chapter-title h1 { font-size: 2.4rem; }
  .chapter-claim { font-size: 1.3rem; }
  .live-demo-line { grid-template-columns: 1fr; }
}

/* Full-bleed photographic slide system. */
@media screen {
  .overview-photo-slide {
    position: relative;
    isolation: isolate;
    overflow: hidden;
    min-height: 100%;
    padding: clamp(2.5rem, 4vw, 5rem);
    display: grid;
    grid-template-rows: minmax(0, 1fr) auto;
    background: var(--paper);
  }
  .overview-photo-slide::before {
    content: "";
    position: absolute;
    z-index: 1;
    inset: 0 auto 0 0;
    width: 53%;
    background: rgb(247 245 239 / 0.82);
    backdrop-filter: blur(2px);
  }
  .overview-photo { position: absolute; z-index: 0; inset: 0; width: 100%; height: 100%; object-fit: cover; object-position: center; }
  .overview-photo-slide .overview-copy { position: relative; z-index: 2; width: 48%; align-self: center; }
  .overview-photo-slide .overview-copy h1 { font-size: clamp(5rem, 7.2vw, 9rem); }
  .overview-photo-slide .overview-copy > p { max-width: 19em; font-size: clamp(1.4rem, 1.9vw, 2rem); }
  .overview-photo-slide .overview-copy > strong { max-width: 23em; font-size: clamp(1.08rem, 1.35vw, 1.4rem); }
  .overview-photo-slide > .method-loop {
    position: relative;
    z-index: 2;
    width: 53%;
    min-height: 6rem;
    background: rgb(255 255 255 / 0.82);
    backdrop-filter: blur(5px);
  }

  .photo-slide {
    position: relative;
    isolation: isolate;
    overflow: hidden;
    min-height: 100%;
    background: var(--bg);
  }
  .photo-slide::before {
    content: "";
    position: absolute;
    z-index: 1;
    inset: 0 auto 0 0;
    width: 56%;
    backdrop-filter: blur(2px);
  }
  .photo-slide.copy-light::before { background: rgb(5 10 24 / 0.78); }
  .photo-slide.copy-dark::before { background: rgb(247 245 239 / 0.84); }
  .slide-photo-layer { position: absolute; z-index: 0; inset: 0; }
  .slide-photo-layer img { width: 100%; height: 100%; display: block; object-fit: cover; object-position: center; }

  .photo-slide .chapter-slide-head {
    position: relative;
    z-index: 2;
    width: 54%;
    padding-bottom: 1.5rem;
  }
  .photo-slide.copy-light .chapter-slide-head { border-color: rgb(255 255 255 / 0.24); }
  .photo-slide.copy-dark .chapter-slide-head { border-color: rgb(20 25 38 / 0.2); }
  .photo-slide.copy-light .chapter-title h1 { color: white; }
  .photo-slide.copy-light .chapter-title > span { color: var(--lime); }
  .photo-slide.copy-light .chapter-tag { border-color: rgb(255 255 255 / 0.3); color: #cbd4e6; }
  .photo-slide.copy-dark .chapter-title h1 { color: var(--ink); }
  .photo-slide .chapter-title h1 { font-size: clamp(72px, 3.8vw, 92px); line-height: 0.98; overflow-wrap: normal; word-break: keep-all; }

  .photo-slide .chapter-ppt-body {
    position: relative;
    z-index: 2;
    width: 52%;
    padding-top: clamp(1.4rem, 2.2vw, 2.5rem);
    display: block;
  }
  .photo-slide .chapter-message { width: 100%; }
  .photo-slide .chapter-claim { max-width: 18em; font-size: clamp(1.7rem, 2.25vw, 2.5rem); line-height: 1.4; }
  .photo-slide.copy-light .chapter-claim { color: white; }
  .photo-slide.copy-dark .chapter-claim { color: var(--ink); }
  .photo-slide .big-points { margin-top: clamp(1.3rem, 2vw, 2.2rem); gap: 0.7rem; }
  .photo-slide .big-points li {
    width: min(100%, 34rem);
    min-height: 3.8rem;
    border-width: 0;
    font-size: clamp(1.08rem, 1.35vw, 1.45rem);
  }
  .photo-slide.copy-light .big-points li { background: rgb(16 24 44 / 0.78); color: #f4f7ff; }
  .photo-slide.copy-dark .big-points li { background: rgb(255 255 255 / 0.78); color: var(--ink); }
  .photo-slide.copy-light .big-points li b { background: var(--lime); color: var(--lime-ink); }
  .photo-slide.copy-dark .big-points li b { background: var(--blue); color: white; }
  .photo-slide .live-demo-line { width: min(100%, 34rem); }
  .photo-slide.copy-light .live-demo-line { border-color: rgb(255 255 255 / 0.55); }
  .photo-slide.copy-light .live-demo-line b { color: #d9e0ee; }
  .photo-slide.copy-dark .live-demo-line { border-color: var(--ink); }
}

@media screen and (max-width: 1180px) {
  .overview-photo-slide .overview-copy { width: 52%; }
  .overview-photo-slide > .method-loop { width: 56%; }
  .photo-slide::before { width: 61%; }
  .photo-slide .chapter-slide-head { width: 59%; }
  .photo-slide .chapter-ppt-body { width: 57%; }
}

@media screen and (max-width: 900px) {
  .overview-photo-slide { min-height: 48rem; padding: 1.4rem; }
  .overview-photo-slide::before { width: 100%; background: rgb(247 245 239 / 0.78); }
  .overview-photo { object-position: 65% center; opacity: 0.5; }
  .overview-photo-slide .overview-copy { width: 100%; }
  .overview-photo-slide .overview-copy h1 { max-width: 7ch; font-size: clamp(3.7rem, 15vw, 5.5rem); }
  .overview-photo-slide .overview-copy > p { font-size: 1.3rem; }
  .overview-photo-slide > .method-loop { width: 100%; min-height: 4.7rem; }

  .photo-slide { min-height: 52rem; padding: 1.4rem; }
  .photo-slide::before { width: 100%; }
  .photo-slide.copy-light::before { background: rgb(5 10 24 / 0.72); }
  .photo-slide.copy-dark::before { background: rgb(247 245 239 / 0.75); }
  .slide-photo-layer img { object-position: 65% center; }
  .photo-slide .chapter-slide-head, .photo-slide .chapter-ppt-body { width: 100%; }
  .photo-slide .chapter-title h1 { font-size: clamp(2.8rem, 11vw, 4.2rem); }
  .photo-slide .chapter-claim { max-width: 19em; font-size: 1.5rem; }
  .photo-slide .big-points li { font-size: 1.03rem; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 1ms !important; }
}

@media print {
  @page { size: A4 portrait; margin: 14mm; }
  body { overflow: visible; background: white; color: black; font-size: 11pt; }
  .course-app, dialog { display: none !important; }
  .print-book { display: block; }
  .print-book > header { margin-bottom: 12mm; }
  .print-book h1 { font-size: 27pt; }
  .print-book article { break-before: page; }
  .print-book h2 { font-size: 21pt; }
  .print-book h3 { margin-top: 5mm; font-size: 13pt; }
  .print-book li { margin-bottom: 2mm; }
  .print-book blockquote { margin: 4mm 0; padding: 4mm; border: 1px solid #aaa; }
  .model-table { font-size: 8.5pt; }
}