:root {
  color-scheme: light;
  --bg: #FFFFFF;
  --ink: #18203A;
  --muted: #626D82;
  --accent: #2346DB;
  --line: #CFD7ED;
  --band: #EAF0FF;
  --surface: #F5F7FC;
  --soft-line: #E9EDF7;
  --button-ink: #FFFFFF;
  --accent-hover: #1935BA;
  --social-line: #BCC7E5;
  --display: "Songti SC", "STSong", "Noto Serif CJK SC", serif;
  --sans: "PingFang SC", -apple-system, "Microsoft YaHei", sans-serif;
  --brand: "Avenir Next", Avenir, "Helvetica Neue", Arial, sans-serif;
  --mono: "SFMono-Regular", Menlo, monospace;
  --gutter: clamp(24px, 4.7vw, 80px);
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #101522;
  --ink: #E6ECFA;
  --muted: #A8B3C9;
  --accent: #9AAEFF;
  --line: #35415B;
  --band: #1A2540;
  --surface: #151D2E;
  --soft-line: #29344B;
  --button-ink: #10182B;
  --accent-hover: #B5C3FF;
  --social-line: #485774;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
  color-scheme: dark;
  --bg: #101522;
  --ink: #E6ECFA;
  --muted: #A8B3C9;
  --accent: #9AAEFF;
  --line: #35415B;
  --band: #1A2540;
  --surface: #151D2E;
  --soft-line: #29344B;
  --button-ink: #10182B;
  --accent-hover: #B5C3FF;
  --social-line: #485774;
  }
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 28px; }
body { margin: 0; color: var(--ink); background: var(--bg); font-family: var(--sans); -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; cursor: pointer; }
img { display: block; max-width: 100%; height: auto; }
svg { display: block; width: 22px; height: 22px; flex-shrink: 0; }
button, a { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible, summary:focus-visible, select:focus-visible { outline: 2px solid var(--accent); outline-offset: 6px; }
::selection { background: var(--accent); color: var(--button-ink); }
.wrap { width: 100%; max-width: 1440px; margin: auto; padding-left: var(--gutter); padding-right: var(--gutter); }
.skip { position: fixed; top: -100px; left: 24px; z-index: 10; padding: 16px; background: var(--accent); color: var(--button-ink); }
.skip:focus { top: 10px; }
h1, h2, h3, p, figure { margin: 0; }
h2 { font-family: var(--display); font-weight: 600; font-size: clamp(30px, 3.1vw, 46px); letter-spacing: -.025em; line-height: 1.4; }
.nav { display: flex; justify-content: space-between; align-items: center; height: 110px; }
.brand { display: inline-flex; gap: 12px; align-items: center; font: 650 28px/1 var(--brand); letter-spacing: -.9px; }
.brand svg { width: 27px; height: 27px; color: var(--accent); }
.nav nav { display: flex; gap: 42px; font-size: 14px; color: var(--muted); }
.nav nav a { display: inline-flex; align-items: center; min-height: 48px; transition: color .18s; }
.nav nav a:hover { color: var(--accent); }
.nav-actions { display: flex; align-items: center; gap: 34px; }
.theme-control { position: relative; display: inline-flex; align-items: center; gap: 8px; min-height: 44px; padding-left: 13px; border: 1px solid var(--line); border-radius: 24px; color: var(--muted); }
.theme-control[hidden] { display: none; }
.theme-control > svg { width: 16px; height: 16px; pointer-events: none; }
.theme-control select { appearance: none; border: 0; border-radius: 24px; background: transparent; color: var(--ink); font: 12px var(--sans); padding: 12px 30px 12px 0; min-height: 44px; cursor: pointer; }
.theme-control select option { color: var(--ink); background: var(--bg); }
.theme-control .theme-chevron { position: absolute; right: 10px; width: 14px; height: 14px; }
.theme-control:hover { border-color: var(--accent); }
.hero { display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 70px; padding-top: 25px; padding-bottom: 70px; min-height: 655px; }
h1 { color: var(--accent); font-family: var(--display); font-size: clamp(64px, 6.7vw, 96px); font-weight: 650; line-height: 1.2; letter-spacing: -.055em; }
h1 > span { display: block; white-space: nowrap; }
h1 em { font-family: Georgia, serif; font-weight: 400; font-style: normal; letter-spacing: -.05em; }
.cursor { display: none; }
.subtitle { font-size: clamp(15px, 1.4vw, 19px); line-height: 1.9; color: var(--muted); margin-top: 26px; max-width: 32em; }
.actions { display: flex; align-items: center; gap: 32px; margin-top: 32px; }
.primary { background: var(--accent); color: var(--button-ink); display: inline-flex; align-items: center; justify-content: center; gap: 24px; border: 1px solid transparent; min-height: 56px; padding: 15px 24px; font-size: 15px; font-weight: 600; transition: transform .2s, background .2s; }
.primary:hover { transform: translateY(-2px); background: var(--accent-hover); }
.secondary { display: inline-flex; align-items: center; gap: 16px; font-size: 15px; min-height: 48px; color: var(--accent); }
.secondary:hover { text-decoration: underline; text-underline-offset: 6px; }
.hero-foot { font-size: 12px; color: var(--muted); margin-top: 24px; letter-spacing: .08em; }
.hero-foot span { margin: 0 8px; color: var(--accent); }
.portrait { width: 100%; max-width: 450px; justify-self: end; margin-right: 18px; }
.portrait-frame { position: relative; margin-bottom: 32px; }
.portrait-frame::before { content: ""; position: absolute; background: var(--accent); inset: 18px -18px -18px 18px; }
.portrait-frame img { position: relative; width: 100%; height: 460px; object-fit: cover; object-position: 50% 38%; }
.portrait figcaption { display: flex; align-items: baseline; justify-content: flex-end; gap: 12px; font-size: 12px; color: var(--muted); }
.photo-name { font: 600 16px/1.4 var(--brand); color: var(--accent); letter-spacing: -.4px; }
.label { font-family: var(--mono); font-size: 12px; letter-spacing: .12em; color: var(--muted); margin-bottom: 22px; }
.body-copy { font-size: 15px; line-height: 2; color: var(--muted); max-width: 35em; margin-top: 24px; }
.small-note { font-size: 12px; color: var(--muted); line-height: 1.8; margin-top: 16px; }
/* The introduction keeps a real space for EP00, with an honest pre-release state. */
.video-section { background: var(--surface); padding: 84px 0 46px; border-top: 1px solid var(--soft-line); }
.video-heading { display: grid; grid-template-columns: 1fr 1fr; gap: 70px; align-items: center; margin-bottom: 42px; }
.video-heading h2 { color: var(--accent); font-size: 40px; }
.video-heading .body-copy { font-size: 14px; }
.video-questions { padding: 0; margin: 0; list-style: none; counter-reset: questions; }
.video-questions li { counter-increment: questions; display: flex; align-items: baseline; gap: 24px; padding: 20px 0; border-top: 1px solid var(--line); font-size: 15px; line-height: 1.7; }
.video-questions li:last-child { border-bottom: 1px solid var(--line); }
.video-questions li::before { content: "0" counter(questions); color: var(--accent); font: 12px var(--mono); }
.video-cover { background: #1A2858; color: #FFF; padding: 28px 40px; aspect-ratio: 16/7; display: flex; flex-direction: column; justify-content: space-between; }
.cover-top, .cover-bottom { display: flex; justify-content: space-between; align-items: center; gap: 16px; font-size: 12px; color: #CAD4F3; }
.video-status { display: flex; align-items: center; gap: 9px; }
.video-status::before { content: ""; display: inline-block; width: 6px; height: 6px; background: #B9CAFF; border-radius: 50%; }
.cover-content { display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 48px; margin: 36px 0; }
.cover-content > p { font-family: var(--display); font-size: clamp(32px, 4.2vw, 60px); line-height: 1.4; }
.cover-transition { display: flex; align-items: center; gap: 26px; justify-content: center; font: 34px Georgia, serif; }
.cover-transition span { color: #BAC6E8; }
.cover-transition strong { font-weight: 400; }
.cover-transition svg { width: clamp(36px, 6vw, 90px); height: 24px; color: #9BADE9; }
.cover-brand { font: 600 17px var(--brand); letter-spacing: -.5px; color: #FFF; }
.video-note { display: flex; align-items: center; justify-content: space-between; gap: 24px; margin-top: 22px; color: var(--muted); font-size: 13px; line-height: 1.9; }
.video-note a { color: var(--accent); min-height: 48px; display: flex; align-items: center; gap: 14px; white-space: nowrap; }
/* Chat/Agent comparison, with the four practical outcomes attached underneath. */
.difference-section { padding: 88px 0 0; }
.difference-section > .wrap > .body-copy { max-width: none; margin-top: 16px; }
.comparison { margin-top: 44px; }
.comparison-head, .comparison-row { display: grid; grid-template-columns: 1fr 1fr; }
.comparison-head > div { display: flex; flex-direction: column; gap: 12px; padding-bottom: 28px; }
.comparison-head > div:nth-child(2), .comparison-row > div:nth-child(2) { padding-left: 48px; border-left: 1px solid var(--line); color: var(--accent); }
.compare-word { font: 42px Georgia, serif; }
.comparison-head > div:first-child .compare-word { color: var(--muted); }
.compare-tag { font-size: 12px; color: var(--muted); }
.comparison-row > div { padding: 23px 28px 23px 0; border-top: 1px solid var(--line); font-size: 17px; line-height: 1.8; }
.comparison-row > div:first-child { color: var(--muted); }
.comparison-row > div:nth-child(2) { font-weight: 500; }
.compare-note { color: var(--muted); font-size: 13px; margin-top: 24px; line-height: 1.8; }
.mobile-tag { display: none; }
.work-band { padding: 38px 0 42px; margin-top: 48px; background: var(--band); }
.section-intro { display: flex; justify-content: space-between; align-items: center; gap: 24px; }
.section-intro h2 { color: var(--accent); font-size: 26px; }
.section-intro p { color: var(--muted); font-size: 13px; line-height: 1.8; }
.topics { display: grid; grid-template-columns: repeat(4, 1fr); margin-top: 28px; }
.topic { padding: 0 24px; border: 0; border-left: 1px solid var(--line); text-align: left; background: none; }
.topic:first-child { padding-left: 0; border-left: 0; }
.topic:last-child { padding-right: 0; }
.topic-name { font-family: var(--display); display: flex; align-items: center; justify-content: space-between; gap: 10px; color: var(--accent); font-size: 24px; line-height: 1.5; font-weight: 600; }
.topic-name svg { width: 18px; transition: transform .2s; }
.topic:hover .topic-name svg { transform: translateX(5px); }
.topic-desc { display: block; margin-top: 12px; max-width: 17em; font-size: 13px; line-height: 1.8; color: var(--muted); }
.progress { padding-top: 100px; padding-bottom: 110px; display: grid; grid-template-columns: 1fr 1.1fr; gap: 90px; }
.progress h2 { font-size: 40px; }
.progress-state { margin-top: 32px; font-size: 13px; display: flex; align-items: center; gap: 10px; }
.progress-state > span { width: 7px; height: 7px; flex-shrink: 0; border-radius: 50%; background: var(--accent); }
.chapter-head { font-size: 12px; color: var(--muted); display: flex; justify-content: space-between; padding-bottom: 18px; border-bottom: 1px solid var(--line); }
details { border-bottom: 1px solid var(--line); }
summary { min-height: 64px; display: flex; align-items: center; gap: 22px; cursor: pointer; list-style: none; font-size: 15px; }
summary::-webkit-details-marker { display: none; }
.chapter-num { font-family: var(--mono); font-size: 11px; color: var(--muted); }
.plus { font-family: var(--mono); margin-left: auto; color: var(--accent); font-size: 20px; font-weight: 300; }
details[open] .plus { transform: rotate(45deg); }
details p { font-size: 13px; line-height: 1.9; color: var(--muted); padding: 0 20px 22px 39px; }
.about-band { padding: 80px 0; background: var(--surface); }
.about { display: grid; grid-template-columns: .95fr 1fr; gap: 90px; align-items: center; }
.about figure { width: 100%; max-width: 480px; justify-self: center; }
.about img { width: 100%; aspect-ratio: 4/3; object-fit: cover; }
.about .label { margin-bottom: 20px; }
.social-area { margin-top: 30px; padding-top: 27px; border-top: 1px solid var(--line); }
.social-area h3 { font-size: 16px; font-weight: 500; }
.social-area > p { color: var(--muted); font-size: 13px; line-height: 1.9; margin-top: 12px; }
.social-links { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 20px; }
.social-link { display: inline-flex; align-items: center; gap: 10px; border: 1px solid var(--social-line); padding: 12px 16px; min-height: 48px; font-size: 14px; transition: background .2s, border-color .2s; }
.social-link:hover { background: var(--bg); border-color: var(--accent); }
.social-link img { width: 22px; height: 22px; aspect-ratio: 1; border-radius: 5px; }
.social-link > svg { width: 19px; height: 19px; }
.social-link > svg:last-child { margin-left: 12px; color: var(--accent); width: 16px; }
.footer { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding-top: 26px; padding-bottom: 26px; font-size: 12px; color: var(--muted); }
.footer a { display: flex; align-items: center; gap: 8px; min-height: 48px; }
.footer svg { width: 17px; height: 17px; }
dialog { background: var(--bg); color: var(--ink); border: 1px solid var(--line); padding: 46px; width: min(540px, calc(100% - 40px)); max-height: 85vh; overflow: auto; border-radius: 8px; }
dialog::backdrop { background: rgba(15, 24, 53, .55); backdrop-filter: blur(6px); }
dialog h2 { font-size: 30px; margin-bottom: 20px; }
dialog > p { font-size: 15px; line-height: 1.8; color: var(--muted); }
.close-dialog { position: absolute; right: 10px; top: 6px; border: 0; background: transparent; font-size: 27px; width: 48px; height: 48px; }
.dialog-result { padding: 24px 0; margin-top: 22px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.dialog-result span { color: var(--accent); font-size: 12px; }
.dialog-result p { font-size: 16px; line-height: 1.8; margin-top: 12px; }
.close-action { margin-top: 26px; width: 100%; }
@media (min-width: 1441px) { .hero { min-height: 720px; } .portrait-frame img { height: 520px; } }
@media (max-width: 1100px) and (min-width: 761px) {
  .hero { gap: 42px; }
  .actions { gap: 18px; }
  .primary { padding: 14px 17px; gap: 12px; }
  .subtitle { max-width: 24em; }
  .portrait-frame img { height: 420px; }
  .section-intro { align-items: flex-start; flex-direction: column; gap: 12px; }
  .topic { padding: 0 15px; }
  .topic-name { font-size: 20px; }
  .progress { gap: 60px; }
  .about { gap: 55px; }
  .video-heading { gap: 40px; }
  .video-heading h2 { font-size: 34px; }
  .cover-transition { font-size: 28px; gap: 16px; }
}
@media (max-width: 760px) {
  :root { --gutter: 24px; }
  .nav { height: auto; min-height: 120px; flex-wrap: wrap; gap: 8px; padding-top: 22px; padding-bottom: 12px; }
  .nav-actions { display: contents; }
  .nav nav { order: 3; width: 100%; }
  .theme-control { margin-left: auto; }
  .theme-control select { font-size: 11px; }
  .brand { font-size: 23px; gap: 8px; letter-spacing: -.65px; }
  .brand svg { width: 23px; height: 23px; }
  .nav nav { gap: 20px; font-size: 12px; }
  .hero { display: flex; flex-direction: column; align-items: stretch; gap: 32px; min-height: 0; padding-top: 32px; padding-bottom: 44px; }
  h1 { font-size: clamp(47px, 12.2vw, 86px); line-height: 1.18; letter-spacing: -.04em; }
  .hero-copy { width: 100%; }
  .subtitle { font-size: 15px; margin-top: 24px; max-width: 26em; }
  .actions { gap: 20px; margin-top: 26px; }
  .primary { min-height: 52px; padding: 13px 17px; gap: 14px; font-size: 14px; }
  .secondary { font-size: 14px; gap: 9px; }
  .secondary svg { width: 18px; }
  .hero-foot { font-size: 11px; margin-top: 20px; }
  .portrait { max-width: none; margin: 0; padding-right: 14px; }
  .portrait-frame img { height: 360px; object-position: 50% 32%; }
  .portrait-frame::before { inset: 14px -14px -14px 14px; }
  .portrait-frame { margin-bottom: 25px; }
  .portrait figcaption { font-size: 11px; gap: 9px; }
  .photo-name { font-size: 14px; }
  .video-section { padding: 48px 0 32px; }
  .video-heading { display: block; margin-bottom: 28px; }
  .video-heading h2 { font-size: 32px; }
  .video-heading .body-copy { font-size: 14px; }
  .video-questions { margin-top: 26px; }
  .video-questions li { font-size: 13px; gap: 16px; padding: 16px 0; }
  .video-cover { aspect-ratio: auto; padding: 20px; min-height: 320px; }
  .cover-top, .cover-bottom { font-size: 10px; }
  .cover-content { display: block; margin: 30px 0; }
  .cover-content > p { font-size: 35px; }
  .cover-transition { justify-content: flex-start; font-size: 21px; gap: 18px; margin-top: 24px; }
  .cover-transition svg { width: 58px; }
  .cover-brand { font-size: 15px; }
  .cover-bottom > span:last-child { display: none; }
  .video-note { display: block; font-size: 12px; margin-top: 18px; }
  .difference-section { padding-top: 52px; }
  .difference-section h2 { font-size: 29px; }
  .comparison { margin-top: 30px; }
  .comparison-head > div:nth-child(2) { padding-left: 24px; }
  .comparison-head > div { padding-bottom: 22px; }
  .compare-word { font-size: 33px; }
  .compare-tag { font-size: 11px; }
  .comparison-row { display: block; padding: 19px 0; border-top: 1px solid var(--line); }
  .comparison-row > div, .comparison-row > div:nth-child(2) { border: 0; padding: 0; font-size: 14px; line-height: 1.9; display: flex; align-items: baseline; gap: 16px; }
  .comparison-row > div:nth-child(2) { margin-top: 12px; }
  .mobile-tag { display: inline-block; width: 38px; flex-shrink: 0; font: 10px var(--mono); }
  .compare-note { font-size: 12px; margin-top: 18px; }
  .work-band { padding: 28px 0 34px; margin-top: 32px; }
  .section-intro { display: block; }
  .section-intro h2 { font-size: 22px; line-height: 1.5; max-width: 14em; }
  .section-intro p { margin-top: 10px; font-size: 12px; }
  .topics { grid-template-columns: 1fr 1fr; row-gap: 28px; margin-top: 26px; }
  .topic, .topic:first-child, .topic:last-child { padding: 0 16px; border: 0; }
  .topic:nth-child(odd) { padding-left: 0; border-right: 1px solid var(--line); }
  .topic:nth-child(even) { padding-right: 0; }
  .topic-name { font-size: 18px; }
  .topic-desc { font-size: 12px; margin-top: 9px; }
  .progress { padding-top: 60px; padding-bottom: 64px; display: block; }
  .progress h2 { font-size: 33px; }
  .body-copy { font-size: 14px; margin-top: 20px; }
  .progress-state { margin-top: 22px; }
  .chapter-list { margin-top: 36px; }
  summary { font-size: 14px; gap: 16px; }
  .label { font-size: 11px; margin-bottom: 16px; }
  .about-band { padding: 48px 0; }
  .about { display: flex; flex-direction: column; gap: 32px; }
  .about figure { width: 100%; max-width: 100%; }
  .about h2 { font-size: 33px; }
  .social-area { margin-top: 24px; padding-top: 24px; }
  .footer { font-size: 10px; flex-wrap: wrap; gap: 14px; padding-top: 18px; padding-bottom: 18px; }
  .footer > span { order: 3; width: 100%; }
  dialog { padding: 32px 24px; }
  dialog h2 { font-size: 26px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}