:root {
  --ground: #eef1f2;
  --surface: #ffffff;
  --surface-2: #e4e9eb;
  --ink: #14191c;
  --ink-soft: #59646b;
  --rule: #d3dbde;
  --accent: #0d5e66;
  --accent-bright: #4ec3cb;
  --accent-soft: #d8ecee;
  --ember: #a8621c;
  --ember-soft: #f6e7d6;
  --white: #f6f8f8;
  --content: 1160px;
  --serif: "Noto Serif TC", Georgia, "Songti TC", serif;
  --sans: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; color: var(--ink); background: var(--ground); font-family: var(--sans); line-height: 1.8; }
a { color: inherit; }
button, summary { font: inherit; }
:focus-visible { outline: 3px solid var(--accent-bright); outline-offset: 4px; }

.skip-link { position: fixed; z-index: 100; top: 12px; left: 12px; padding: 10px 15px; color: var(--white); background: var(--accent); transform: translateY(-160%); }
.skip-link:focus { transform: none; }
.nav { position: fixed; z-index: 20; top: 0; right: 0; left: 0; color: var(--white); transition: background .25s, border-color .25s; }
.nav.scrolled { background: rgba(16, 20, 22, .94); border-bottom: 1px solid rgba(255, 255, 255, .1); backdrop-filter: blur(16px); }
.nav-inner { width: min(calc(100% - 48px), var(--content)); height: 76px; margin: auto; display: flex; align-items: center; gap: 36px; }
.nav-logo { margin-right: auto; display: flex; align-items: center; gap: 10px; font-family: var(--serif); font-size: 20px; font-weight: 900; text-decoration: none; }
.nav-logo img { width: 36px; height: 36px; border-radius: 9px; }
.nav-links { display: flex; gap: 25px; }
.nav-links a { color: rgba(255, 255, 255, .72); font-size: 13px; font-weight: 700; text-decoration: none; }
.nav-links a:hover { color: var(--white); }

.button { min-height: 48px; padding: 12px 20px; display: inline-flex; align-items: center; justify-content: center; border: 1px solid transparent; text-decoration: none; font-weight: 700; }
.button--primary { color: #fff; background: var(--accent); }
.button--ghost { color: var(--white); border-color: rgba(255, 255, 255, .3); }
.button--nav { min-height: 40px; padding: 8px 16px; color: var(--ink); background: var(--accent-bright); font-size: 13px; }

.hero { min-height: 680px; position: relative; overflow: hidden; color: var(--white); background: #101416; }
.hero::before { content: ""; position: absolute; inset: 0; opacity: .16; background-image: linear-gradient(rgba(255, 255, 255, .12) 1px, transparent 1px), linear-gradient(90deg, rgba(255, 255, 255, .12) 1px, transparent 1px); background-size: 64px 64px; mask-image: linear-gradient(#000, transparent 92%); }
.hero-inner { width: min(calc(100% - 48px), var(--content)); min-height: 620px; margin: auto; padding: 122px 0 84px; display: grid; grid-template-columns: .88fr 1.12fr; align-items: center; gap: 64px; }
.hero-copy, .hero-product { position: relative; z-index: 1; }
.hero-identity { margin-bottom: 22px; display: flex; align-items: center; gap: 13px; }
.hero-identity img { width: 48px; height: 48px; border-radius: 12px; }
.hero-identity div { display: grid; gap: 1px; }
.hero-identity strong { font-family: var(--serif); font-size: 20px; line-height: 1.35; }
.hero-identity span { color: var(--accent-bright); font-family: var(--mono); font-size: 9px; font-weight: 500; letter-spacing: .12em; }
.eyebrow { margin: 0 0 22px; color: var(--accent); font-family: var(--mono); font-size: 12px; font-weight: 500; letter-spacing: .14em; }
.hero .eyebrow, .section--ink .eyebrow, .contact .eyebrow { color: var(--accent-bright); }
h1, h2, h3 { margin-top: 0; }
h1, h2 { font-family: var(--serif); font-weight: 900; }
h1 { margin-bottom: 28px; font-size: clamp(52px, 6.5vw, 88px); line-height: 1.16; }
h1 span { color: var(--accent-bright); }
h2 { margin-bottom: 25px; font-size: clamp(36px, 4.8vw, 60px); line-height: 1.3; }
.hero-lead { max-width: 580px; margin: 0; color: rgba(255, 255, 255, .68); font-size: 18px; }
.hero-actions { margin-top: 36px; display: flex; gap: 12px; flex-wrap: wrap; }
.hero-product { width: min(100%, 620px); justify-self: center; padding: 12px; background: #1f272b; box-shadow: 0 30px 80px rgba(0, 0, 0, .42); transform: rotate(1.5deg); }
.hero-product::before { content: ""; position: absolute; z-index: -1; inset: -18px 22px 24px -20px; border: 1px solid rgba(255, 255, 255, .16); }
.hero-product > span { padding: 12px 3px 2px; display: block; color: #97a5ac; font-family: var(--mono); font-size: 11px; letter-spacing: .1em; }
.hero-widget { overflow: hidden; color: var(--ink); background: var(--ground); border: 1px solid rgba(255, 255, 255, .1); transform: rotate(-1.5deg); }
.hero-widget-bar { min-height: 68px; padding: 13px 18px; display: flex; align-items: center; justify-content: space-between; gap: 18px; color: var(--white); background: var(--accent); }
.hero-widget-identity { display: flex; align-items: center; gap: 11px; }
.hero-widget-identity img { width: 38px; height: 38px; border-radius: 9px; }
.hero-widget-identity div { display: grid; gap: 1px; }
.hero-widget-identity strong { font-family: var(--serif); font-size: 18px; line-height: 1.25; }
.hero-widget-identity span { color: rgba(255, 255, 255, .68); font-size: 11px; line-height: 1.35; }
.hero-widget-online { display: flex; align-items: center; gap: 7px; font-size: 12px; font-weight: 700; }
.hero-widget-online i { width: 8px; height: 8px; display: block; background: var(--accent-bright); border-radius: 50%; box-shadow: 0 0 0 4px rgba(78, 195, 203, .18); }
.hero-widget-thread { min-height: 330px; padding: 24px; display: flex; flex-direction: column; gap: 14px; }
.hero-widget-message { padding: 15px 17px; border-radius: 14px; }
.hero-widget-message > span { display: block; margin-bottom: 5px; font-size: 12px; font-weight: 700; }
.hero-widget-message p { margin: 0; font-size: 16px; line-height: 1.65; }
.hero-widget-message--user { max-width: 76%; margin-left: auto; color: #072e32; background: #9ce3e7; border-bottom-right-radius: 4px; }
.hero-widget-message--user > span { color: #276970; }
.hero-widget-message--assistant { max-width: 88%; background: var(--surface); border: 1px solid var(--rule); border-bottom-left-radius: 4px; box-shadow: 0 8px 22px rgba(20, 25, 28, .07); }
.hero-widget-message--assistant > span { color: var(--accent); }
.hero-widget-search { align-self: center; padding: 8px 12px; display: flex; align-items: center; gap: 10px; color: var(--ink-soft); background: var(--surface-2); border-radius: 999px; font-size: 12px; line-height: 1.3; }
.hero-widget-search i { color: var(--accent); font-style: normal; }
.hero-widget-search strong { color: var(--accent); }
.hero-widget-source { margin-top: 12px; padding: 10px 12px; display: flex; align-items: center; justify-content: space-between; gap: 16px; background: var(--accent-soft); border-left: 3px solid var(--accent); }
.hero-widget-source span { color: var(--ink-soft); font-size: 12px; }
.hero-widget-source strong { color: var(--accent); font-size: 13px; }
.hero-widget-compose { min-height: 58px; padding: 10px 12px 10px 18px; display: flex; align-items: center; justify-content: space-between; gap: 12px; color: #78848a; background: var(--surface); border-top: 1px solid var(--rule); font-size: 14px; }
.hero-widget-compose i { width: 38px; height: 38px; display: grid; place-items: center; color: var(--white); background: var(--accent); border-radius: 50%; font-size: 20px; font-style: normal; line-height: 1; }
.scenario-shell { border: 1px solid rgba(255, 255, 255, .15); background: #171d20; box-shadow: 0 30px 80px rgba(0, 0, 0, .35); }
.message { max-width: 82%; padding: 14px 17px; border-radius: 14px; }
.message p { margin: 0; }
.message p + p { margin-top: 10px; }
.message--user { margin-left: auto; color: #08191b; background: var(--accent-bright); border-bottom-right-radius: 4px; }
.message--assistant { color: #e6ebed; background: #2a3439; border-bottom-left-radius: 4px; }
.answer-state { margin-top: 12px; display: block; color: var(--accent-bright); font-family: var(--mono); font-size: 11px; }
.answer-state--boundary { color: #de9a55; }
.scroll-cue { position: absolute; right: 0; bottom: 28px; left: 0; z-index: 2; color: rgba(255, 255, 255, .6); font-size: 12px; text-align: center; text-decoration: none; }

.section { padding: 112px 0; border-top: 1px solid var(--rule); }
.section--tinted { background: var(--surface-2); }
.section--ink { color: var(--white); background: var(--ink); border-color: #2a3439; }
.section-inner { width: min(calc(100% - 48px), var(--content)); margin: auto; }
.narrow { max-width: 760px; }
.section-lead { margin: 0; color: var(--ink-soft); font-size: 19px; }
.section-heading { margin-bottom: 58px; display: grid; grid-template-columns: 1fr .72fr; gap: 70px; align-items: end; }
.section-heading h2 { margin-bottom: 0; }
.section-heading > p { margin: 0 0 9px; color: var(--ink-soft); }
.section--ink .section-heading > p { color: #97a5ac; }

.method-list, .workflow-list { margin: 0; padding: 0; display: grid; grid-template-columns: repeat(4, 1fr); list-style: none; border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); }
.method-list li, .workflow-list li { min-height: 270px; padding: 30px 24px; border-right: 1px solid var(--rule); }
.method-list li:last-child, .workflow-list li:last-child { border-right: 0; }
.method-list span, .workflow-list span, .feature > span { font-family: var(--mono); font-size: 11px; }
.method-list span, .workflow-list span { color: var(--accent); }
.feature > span { color: var(--accent-bright); }
.method-list h3, .workflow-list h3 { margin: 54px 0 13px; font-size: 20px; }
.method-list p, .workflow-list p, .feature p, .quality-item p { margin: 0; color: var(--ink-soft); font-size: 14px; }

.scenario-shell { max-width: 900px; margin: auto; overflow: hidden; }
.scenario-tabs { padding: 10px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; background: #1f272b; border-bottom: 1px solid #2a3439; }
.scenario-tab { min-height: 48px; color: #97a5ac; background: transparent; border: 1px solid transparent; cursor: pointer; }
.scenario-tab.is-active { color: #08191b; background: var(--accent-bright); }
.scenario-panel { min-height: 330px; padding: 50px 40px; display: flex; flex-direction: column; justify-content: center; gap: 20px; }
.js .scenario-panel:not(.is-active) { display: none; }

.feature-grid, .quality-grid { display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid #2a3439; border-left: 1px solid #2a3439; }
.feature { min-height: 220px; padding: 30px; border-right: 1px solid #2a3439; border-bottom: 1px solid #2a3439; }
.feature h3, .quality-item h3 { margin: 38px 0 12px; font-family: var(--serif); font-size: 22px; }
.feature p { color: #97a5ac; }
.workflow-list li { background: var(--surface); }
.quality-grid { grid-template-columns: repeat(4, 1fr); border-color: var(--rule); }
.quality-item { min-height: 220px; padding: 30px 25px; border-right: 1px solid var(--rule); border-bottom: 1px solid var(--rule); background: var(--surface); }
.quality-item h3 { color: var(--accent); }

.faq-layout { display: grid; grid-template-columns: .72fr 1fr; gap: 90px; align-items: start; }
.faq-list { border-top: 1px solid var(--rule); }
.faq-list details { border-bottom: 1px solid var(--rule); }
.faq-list summary { padding: 24px 42px 24px 0; position: relative; cursor: pointer; font-weight: 700; list-style: none; }
.faq-list summary::after { content: "+"; position: absolute; right: 8px; color: var(--accent); font-family: var(--mono); }
.faq-list details[open] summary::after { content: "−"; }
.faq-list p { margin: -4px 0 26px; color: var(--ink-soft); }

.contact { padding: 120px 24px; color: var(--white); background: #101416; text-align: center; }
.contact-inner { max-width: 850px; margin: auto; }
.contact h2 { margin-bottom: 25px; }
.contact p:not(.eyebrow) { max-width: 650px; margin: 0 auto 34px; color: rgba(255, 255, 255, .65); }
.contact small { margin-top: 15px; display: block; color: rgba(255, 255, 255, .45); }
.footer { min-height: 110px; padding: 28px max(24px, calc((100% - var(--content)) / 2)); display: grid; grid-template-columns: 1fr auto auto; align-items: center; gap: 30px; color: var(--ink-soft); background: var(--ground); font-size: 12px; }
.footer a { color: var(--ink); font-family: var(--serif); font-size: 16px; font-weight: 900; text-decoration: none; }

.js .reveal { opacity: 0; transform: translateY(16px); transition: opacity .65s ease, transform .65s ease; }
.js .reveal.is-visible { opacity: 1; transform: none; }

@media (max-width: 900px) {
  .nav-links { display: none; }
  .hero-inner { grid-template-columns: 1fr; gap: 56px; }
  .hero-copy { padding-top: 30px; }
  .hero-product { width: min(100%, 560px); }
  .section-heading { grid-template-columns: 1fr; gap: 20px; }
  .method-list, .workflow-list { grid-template-columns: 1fr 1fr; }
  .method-list li:nth-child(2), .workflow-list li:nth-child(2) { border-right: 0; }
  .method-list li:nth-child(-n+2), .workflow-list li:nth-child(-n+2) { border-bottom: 1px solid var(--rule); }
  .feature-grid { grid-template-columns: 1fr 1fr; }
  .quality-grid { grid-template-columns: 1fr 1fr; }
  .faq-layout { grid-template-columns: 1fr; gap: 35px; }
}

@media (max-width: 560px) {
  .nav-inner, .hero-inner, .section-inner { width: calc(100% - 32px); }
  .nav-inner { height: 68px; }
  .button--nav { min-height: 38px; }
  .hero-inner { min-height: 0; padding: 98px 0 52px; gap: 28px; }
  h1 { margin-bottom: 18px; font-size: 44px; }
  h2 { font-size: 36px; }
  .hero-lead, .section-lead { font-size: 15px; }
  .hero-identity { margin-bottom: 14px; }
  .hero-identity img { width: 40px; height: 40px; border-radius: 10px; }
  .hero-identity strong { font-size: 18px; }
  .hero-identity span { font-size: 8px; }
  .hero-actions { align-items: stretch; flex-direction: column; }
  .hero-actions { margin-top: 24px; gap: 8px; }
  .hero-actions .button { min-height: 44px; padding-block: 9px; }
  .hero-product { width: 100%; padding: 8px; }
  .hero-product > span { padding-top: 8px; font-size: 8px; }
  .hero-widget-bar { min-height: 60px; padding: 11px 13px; }
  .hero-widget-identity img { width: 34px; height: 34px; }
  .hero-widget-identity strong { font-size: 16px; }
  .hero-widget-thread { min-height: 0; padding: 16px 13px; gap: 11px; }
  .hero-widget-message { padding: 12px 13px; }
  .hero-widget-message > span { font-size: 11px; }
  .hero-widget-message p { font-size: 14px; line-height: 1.55; }
  .hero-widget-message--user, .hero-widget-message--assistant { max-width: 94%; }
  .hero-widget-search { padding: 7px 10px; gap: 7px; font-size: 11px; }
  .hero-widget-source { align-items: flex-start; flex-direction: column; gap: 2px; }
  .hero-widget-compose { min-height: 52px; padding-left: 14px; font-size: 13px; }
  .hero-widget-compose i { width: 34px; height: 34px; }
  .scroll-cue { bottom: 12px; }
  .message { max-width: 92%; font-size: 14px; }
  .section { padding: 84px 0; }
  .method-list, .workflow-list, .feature-grid, .quality-grid { grid-template-columns: 1fr; }
  .method-list li, .workflow-list li { min-height: 210px; border-right: 0; border-bottom: 1px solid var(--rule); }
  .method-list li:last-child, .workflow-list li:last-child { border-bottom: 0; }
  .method-list h3, .workflow-list h3 { margin-top: 30px; }
  .scenario-tabs { grid-template-columns: 1fr; }
  .scenario-panel { min-height: 360px; padding: 34px 18px; }
  .footer { grid-template-columns: 1fr auto; gap: 12px; }
  .footer p:first-of-type { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .reveal { opacity: 1; transform: none; transition: none; }
}