:root {
  --blue: #164cff;
  --blue-dark: #103dcc;
  --ink: #10131c;
  --body: #343a48;
  --muted: #6b7280;
  --line: #dfe3ea;
  --soft: #f7f8fa;
  --white: #ffffff;
  --max: 1180px;
  --reading: 790px;
  --radius: 8px;
  --shadow: 0 12px 34px rgba(17, 24, 39, 0.12);
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", system-ui, -apple-system, sans-serif;
  color: var(--ink);
  background: var(--white);
  font-synthesis: none;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; color: var(--body); background: var(--white); line-height: 1.75; }
body, button { font-family: inherit; }
a { color: inherit; text-decoration: none; }
img, video { display: block; max-width: 100%; }
button { font-size: 14px; }
button, a { -webkit-tap-highlight-color: transparent; }
svg { display: block; }
[hidden] { display: none !important; }

:focus-visible { outline: 3px solid rgba(22, 76, 255, 0.35); outline-offset: 3px; }
.skip-link { position: fixed; left: 16px; top: -80px; z-index: 200; padding: 10px 14px; color: #fff; background: var(--blue); }
.skip-link:focus { top: 12px; }
.section-inner, .header-inner, .site-footer-inner { width: min(calc(100% - 48px), var(--max)); margin: 0 auto; }

.site-header { position: sticky; top: 0; z-index: 40; background: rgba(255,255,255,.97); border-bottom: 1px solid var(--line); backdrop-filter: blur(12px); }
.header-inner { min-height: 68px; display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 34px; }
.brand { color: var(--ink); font-size: 24px; font-weight: 900; line-height: 1; letter-spacing: -.04em; }
.site-nav { display: flex; align-items: stretch; justify-content: center; gap: 34px; align-self: stretch; }
.site-nav a { position: relative; display: flex; align-items: center; color: #292f3b; font-size: 14px; font-weight: 650; }
.site-nav a::after { content: ""; position: absolute; left: 0; right: 0; bottom: 0; height: 3px; background: var(--blue); transform: scaleX(0); transition: transform 160ms ease; }
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--blue); }
.site-nav a:hover::after, .site-nav a[aria-current="page"]::after { transform: scaleX(1); }
.nav-toggle { display: none; width: 42px; height: 42px; padding: 9px; color: var(--ink); background: #fff; border: 1px solid var(--line); border-radius: 6px; }
.nav-toggle svg { width: 100%; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; }
.header-wechat { display: inline-flex; align-items: center; gap: 8px; min-height: 40px; padding: 0 16px; color: #fff; background: var(--blue); border: 0; border-radius: 6px; font-weight: 750; cursor: pointer; }
.header-wechat:hover { background: var(--blue-dark); }
.header-wechat svg { width: 19px; height: 19px; fill: currentColor; }

/* Homepage portal */
.eyebrow { margin: 0 0 18px; color: var(--blue); font-size: 13px; font-weight: 850; letter-spacing: .14em; text-transform: uppercase; }
.home-hero { padding: 96px 0 76px; border-bottom: 1px solid var(--line); }
.home-hero h1 { max-width: 900px; margin: 0; color: var(--ink); font-size: clamp(50px, 6.4vw, 82px); line-height: 1.08; letter-spacing: -.06em; }
.home-hero .section-inner > p:last-child { max-width: 760px; margin: 24px 0 0; color: var(--muted); font-size: 19px; }
.home-destinations { padding: 18px 0 90px; }
.home-destination { width: 100%; display: grid; grid-template-columns: 70px minmax(0, 1fr) auto; gap: 28px; align-items: center; padding: 34px 0; color: var(--ink); background: none; border: 0; border-bottom: 1px solid var(--line); text-align: left; cursor: pointer; }
.home-destination:hover h2, .home-destination:hover .destination-action { color: var(--blue); }
.destination-number { color: var(--blue); font-size: 18px; font-weight: 800; }
.home-destination h2 { margin: 0 0 6px; font-size: 29px; letter-spacing: -.03em; transition: color 160ms; }
.home-destination p { margin: 0; color: var(--muted); font-size: 15px; }
.destination-action { display: inline-flex; align-items: center; gap: 10px; color: #4b5260; font-weight: 750; white-space: nowrap; transition: color 160ms; }
.destination-action svg { width: 22px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }

/* Free document library */
.library-shell-page .site-header { height: 92px; }
.library-shell-page .header-inner { width: calc(100% - 88px); max-width: none; min-height: 92px; }
.library-page { min-height: calc(100vh - 92px); display: grid; grid-template-columns: 260px minmax(0, 1fr) 260px; grid-template-rows: auto 1fr; grid-template-areas: "sidebar hero rail" "sidebar documents rail"; }
.library-sidebar { grid-area: sidebar; padding: 74px 40px 68px; border-right: 1px solid var(--line); }
.library-sidebar .filter-row { display: grid; gap: 22px; margin: 0; }
.library-sidebar .filter-button { position: relative; justify-self: stretch; padding: 0 0 0 25px; color: #242a36; background: none; border: 0; border-radius: 0; font-size: 17px; font-weight: 650; line-height: 1.4; text-align: left; }
.library-sidebar .filter-button::before { content: ""; position: absolute; left: 0; top: 50%; width: 3px; height: 30px; background: transparent; transform: translateY(-50%); }
.library-sidebar .filter-button:hover { color: var(--blue); background: none; }
.library-sidebar .filter-button.is-active { color: var(--blue); background: none; }
.library-sidebar .filter-button.is-active::before { background: var(--blue); }
.library-hero { grid-area: hero; margin: 0 44px; padding: 76px 0 48px; border-bottom: 1px solid var(--line); }
.library-hero h1 { margin: 0; color: var(--ink); font-size: clamp(44px, 4vw, 58px); line-height: 1.08; letter-spacing: -.05em; }
.library-hero > p { max-width: 680px; margin: 18px 0 0; color: var(--muted); font-size: 17px; }
.library-content { grid-area: documents; margin: 0 44px; padding: 0 0 120px; }
.document-list { border-bottom: 1px solid var(--line); }
.document-row { display: grid; grid-template-columns: 230px minmax(0, 1fr); gap: 32px; align-items: center; padding: 46px 0; }
.document-row .document-cover { aspect-ratio: 1.46 / 1; border-radius: 5px; }
.document-row .document-copy h3 { font-size: clamp(24px, 1.95vw, 28px); }
.document-row .document-copy p { margin: 13px 0 0; }
.document-row .arrow-link { margin-top: 18px; }
.library-content .empty-state { margin-left: 0; border-top: 0; }
.library-wechat-rail { grid-area: rail; border-left: 1px solid var(--line); }
.library-shell-page .wechat-widget { right: 22px; top: 140px; align-items: center; transform: none; }
.library-shell-page .wechat-collapse { width: 32px; min-height: 112px; padding: 10px 6px; }
.library-shell-page .wechat-collapse span { display: none; }
.library-shell-page .wechat-panel { width: 210px; padding: 28px 19px 26px; border-right: 1px solid #d5dae3; border-radius: 10px; }
.library-shell-page .wechat-title { margin-bottom: 20px; font-size: 17px; }
.library-shell-page .wechat-qr-crop { width: 170px; height: 170px; }
.library-shell-page .wechat-name { margin-top: 4px; }

.portal-hero { padding: 68px 0 0; }
.portal-hero h1 { max-width: 880px; margin: 0; color: var(--ink); font-size: clamp(46px, 5.8vw, 76px); line-height: 1.12; letter-spacing: -.055em; }
.portal-hero > .section-inner > p { max-width: 840px; margin: 20px 0 0; color: #4c5361; font-size: 20px; line-height: 1.8; }
.topic-rail { display: grid; grid-template-columns: repeat(4, 1fr); margin-top: 54px; border-bottom: 1px solid var(--line); }
.topic-rail-item { position: relative; display: flex; align-items: center; justify-content: center; gap: 12px; min-height: 64px; color: #292f3b; font-size: 17px; }
.topic-rail-item + .topic-rail-item::before { content: ""; position: absolute; left: 0; height: 28px; border-left: 1px solid var(--line); }
.topic-rail-item::after { content: ""; position: absolute; left: 0; right: 0; bottom: -1px; height: 3px; background: var(--blue); transform: scaleX(0); }
.topic-rail-item:hover, .topic-rail-item.is-active { color: var(--blue); }
.topic-rail-item:hover::after, .topic-rail-item.is-active::after { transform: scaleX(1); }
.topic-icon { width: 25px; height: 25px; fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }

.portal-section { padding: 42px 0 24px; }
.number-heading { display: flex; align-items: baseline; gap: 18px; margin-bottom: 20px; }
.number-heading > span { color: var(--blue); font-size: 24px; font-weight: 850; letter-spacing: -.03em; }
.number-heading h2 { margin: 0; color: var(--ink); font-size: 25px; line-height: 1.2; letter-spacing: -.025em; }
.filter-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 22px 52px; }
.filter-button { padding: 6px 12px; color: #656c79; background: #fff; border: 1px solid var(--line); border-radius: 4px; cursor: pointer; }
.filter-button:hover, .filter-button.is-active { color: var(--blue); border-color: #9db2ff; background: #f6f8ff; }
.featured-document { display: grid; grid-template-columns: 310px 1fr; gap: 36px; margin-left: 52px; padding: 26px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.document-cover { aspect-ratio: 16 / 9; overflow: hidden; background: #e9edf5; border-radius: var(--radius); }
.document-cover img { width: 100%; height: 100%; object-fit: cover; transition: transform 250ms ease; }
.document-cover:hover img { transform: scale(1.025); }
.document-copy { align-self: center; }
.document-tags { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 12px; color: var(--blue); font-size: 13px; font-weight: 750; }
.document-tags span + span::before { content: "/"; margin-right: 10px; color: #b0b7c3; }
.document-copy h3 { margin: 0; color: var(--ink); font-size: clamp(24px, 2.8vw, 34px); line-height: 1.35; letter-spacing: -.035em; }
.document-copy h3 a:hover { color: var(--blue); }
.document-copy p { max-width: 720px; margin: 12px 0 20px; color: var(--muted); font-size: 16px; }
.arrow-link { display: inline-flex; align-items: center; gap: 10px; color: var(--blue); font-weight: 750; }
.arrow-link svg, .button svg, .topic-card svg { width: 21px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.empty-state { margin-left: 52px; padding: 54px 24px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); text-align: center; }
.empty-state strong { color: var(--ink); font-size: 22px; }
.empty-state p { margin: 6px 0 0; color: var(--muted); }
.topic-section { padding-top: 24px; }
.topic-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-left: 52px; }
.topic-card { min-height: 74px; display: flex; align-items: center; justify-content: space-between; gap: 18px; padding: 16px 20px; color: var(--ink); border: 1px solid #aeb5c0; border-radius: 5px; font-weight: 700; transition: border-color 160ms, color 160ms; }
.topic-card:hover { color: var(--blue); border-color: var(--blue); }
.topic-card small { display: block; margin-top: 2px; color: #8a919d; font-size: 11px; font-weight: 500; }
.topic-card.is-empty { color: #515866; }
.pro-strip-section { padding-bottom: 62px; }
.pro-strip { display: grid; grid-template-columns: 150px minmax(0,1fr) auto; gap: 36px; align-items: center; margin-left: 52px; padding: 28px 0 16px; border-top: 1px solid var(--line); }
.pro-price { display: grid; }
.pro-price strong { color: var(--blue); font-size: 42px; line-height: 1; letter-spacing: -.04em; }
.pro-price span { margin-top: 8px; color: var(--muted); font-size: 13px; }
.pro-strip ul { display: grid; grid-template-columns: 1fr 1fr; gap: 20px 30px; margin: 0; padding: 0; list-style: none; }
.pro-strip li { display: flex; gap: 10px; align-items: flex-start; color: #303644; font-size: 15px; }
.pro-strip li > span { color: var(--blue); font-weight: 900; }
.payment-note { margin: 0 0 0 202px; color: #858c98; font-size: 12px; }

.button { display: inline-flex; align-items: center; justify-content: center; gap: 9px; min-height: 46px; padding: 0 20px; border-radius: 5px; font-weight: 750; cursor: pointer; }
.button-primary { color: #fff; background: var(--blue); border: 1px solid var(--blue); }
.button-primary:hover { background: var(--blue-dark); border-color: var(--blue-dark); }

.site-footer { border-top: 1px solid var(--line); padding: 26px 0; }
.site-footer-inner { display: grid; grid-template-columns: auto 1fr auto; gap: 36px; align-items: center; }
.site-footer .brand { font-size: 20px; }
.footer-nav { display: flex; gap: 24px; color: #5d6470; font-size: 13px; }
.footer-nav a:hover { color: var(--blue); }
.footer-meta { color: #8a919d; font-size: 12px; }

/* Article */
.article-layout { width: min(calc(100% - 48px), var(--max)); display: grid; grid-template-columns: 210px minmax(0, var(--reading)); gap: 58px; margin: 0 auto; padding: 58px 0 100px; }
.article-toc { position: sticky; top: 96px; align-self: start; max-height: calc(100vh - 120px); overflow: auto; padding-right: 26px; border-right: 1px solid var(--line); }
.article-toc > strong { display: block; margin-bottom: 13px; color: var(--ink); font-size: 15px; }
.article-toc nav { display: grid; }
.article-toc a { padding: 6px 0; color: #636a77; font-size: 13px; line-height: 1.5; }
.article-toc a:hover { color: var(--blue); }
.toc-copy-button { width: 100%; margin-top: 22px; padding: 9px 12px; color: var(--blue); background: #fff; border: 1px solid #b6c5fa; border-radius: 5px; cursor: pointer; }
.article-content { min-width: 0; }
.article-header { padding-bottom: 38px; border-bottom: 1px solid var(--line); }
.article-header h1 { margin: 0; color: var(--ink); font-size: clamp(40px, 4.4vw, 58px); line-height: 1.16; letter-spacing: -.05em; }
.article-header > p { margin: 18px 0 0; color: var(--muted); font-size: 18px; }
.mobile-toc { display: none; }
.article-content > section { scroll-margin-top: 92px; padding-top: 58px; }
.article-content h2 { margin: 0 0 16px; color: var(--ink); font-size: 30px; line-height: 1.32; letter-spacing: -.03em; }
.article-content h3 { margin: 30px 0 12px; color: var(--ink); font-size: 20px; line-height: 1.4; }
.article-content h4 { margin: 0 0 7px; color: var(--ink); font-size: 17px; }
.article-content p { margin: 12px 0; color: #3e4552; }
.article-content ol { margin: 8px 0 0; padding-left: 1.3em; }
.article-callout { display: flex; gap: 14px; margin: 30px 0 0; padding: 18px 20px; color: #2d3a59; background: #f6f8ff; border: 1px solid #bdcafd; border-left: 4px solid var(--blue); }
.article-callout > span { flex: 0 0 auto; }
.article-callout p { margin: 0; color: inherit; }
.article-callout p + p { margin-top: 8px; }
.table-scroll { width: 100%; overflow-x: auto; margin: 24px 0; border: 1px solid var(--line); }
table { width: 100%; min-width: 680px; border-collapse: collapse; font-size: 14px; line-height: 1.65; }
th, td { padding: 12px 14px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th:last-child, td:last-child { border-right: 0; }
tr:last-child td { border-bottom: 0; }
th { color: var(--ink); background: var(--soft); font-weight: 800; }
.code-block { position: relative; margin: 18px 0; color: #e6edf7; background: #111827; border-radius: 7px; overflow: hidden; }
.code-block button { position: absolute; right: 10px; top: 10px; z-index: 1; padding: 6px 10px; color: #fff; background: #284fd4; border: 0; border-radius: 4px; cursor: pointer; font-size: 12px; font-weight: 700; }
.code-block pre { max-height: 480px; overflow: auto; margin: 0; padding: 48px 22px 22px; white-space: pre-wrap; overflow-wrap: anywhere; }
.code-block code { font: 13px/1.8 "Cascadia Code", "SFMono-Regular", Consolas, monospace; }
.code-block-long pre { max-height: 620px; }
.example-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.example-grid > div > h3 { margin-top: 16px; }
.article-media { margin: 24px 0; }
.article-media img { width: 100%; max-height: 680px; object-fit: contain; background: var(--soft); border: 1px solid var(--line); }
.article-media figcaption { margin-top: 9px; color: var(--muted); font-size: 13px; text-align: center; }
.media-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.media-pair .article-media img { aspect-ratio: 4 / 3; object-fit: contain; }
.video-comparison { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; margin: 20px 0 28px; }
.video-comparison figure { margin: 0; padding: 14px; border: 1px solid var(--line); }
.video-comparison figcaption { margin-bottom: 12px; color: var(--ink); font-weight: 800; text-align: center; }
.video-comparison video { width: 100%; aspect-ratio: 9 / 16; max-height: 620px; background: #0b0d12; object-fit: contain; }
.responsibility-grid { display: grid; grid-template-columns: repeat(3, 1fr); margin: 18px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.responsibility-grid > div { padding: 24px 22px; }
.responsibility-grid > div + div { border-left: 1px solid var(--line); }
.responsibility-grid p { margin: 0; color: var(--muted); font-size: 14px; }
.section-label { margin-bottom: 5px !important; color: var(--blue) !important; font-size: 14px; font-weight: 800; }
.face-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; margin-top: 24px; }
.face-grid figure { margin: 0; border: 1px solid var(--line); }
.face-grid figcaption { padding: 14px 16px; color: var(--ink); font-weight: 750; border-bottom: 1px solid var(--line); }
.face-grid img { width: 100%; aspect-ratio: 4 / 3; object-fit: contain; background: var(--soft); }
.article-end { display: flex; justify-content: space-between; align-items: center; margin-top: 70px; padding-top: 26px; border-top: 1px solid var(--line); }
.article-end a, .article-end button { color: var(--blue); background: none; border: 0; font-weight: 750; cursor: pointer; }

/* Pro */
.pro-hero { padding: 88px 0 74px; border-bottom: 1px solid var(--line); }
.pro-hero .section-inner { display: grid; grid-template-columns: minmax(0, 1fr) 250px; gap: 80px; align-items: center; }
.pro-hero h1 { max-width: 820px; margin: 0; color: var(--ink); font-size: clamp(46px, 5vw, 68px); line-height: 1.15; letter-spacing: -.055em; }
.pro-hero-copy > p { max-width: 740px; margin: 22px 0 30px; color: var(--muted); font-size: 18px; }
.pro-price-card { padding: 34px 0 34px 40px; border-left: 1px solid var(--line); }
.pro-price-card span, .pro-price-card p { display: block; color: var(--muted); font-size: 13px; }
.pro-price-card strong { display: block; margin: 12px 0; color: var(--blue); font-size: 62px; line-height: 1; letter-spacing: -.05em; }
.pro-benefits, .pro-fit { padding: 68px 0; }
.benefit-rows { margin-left: 52px; border-top: 1px solid var(--line); }
.benefit-rows article { display: grid; grid-template-columns: 80px 1fr; gap: 24px; padding: 32px 0; border-bottom: 1px solid var(--line); }
.benefit-number { color: var(--blue); font-size: 24px; }
.benefit-rows h3 { margin: 0 0 8px; color: var(--ink); font-size: 24px; }
.benefit-rows p { max-width: 780px; margin: 0; color: var(--muted); }
.pro-fit { background: var(--soft); }
.fit-list { display: grid; grid-template-columns: repeat(3, 1fr); margin-left: 52px; border-top: 1px solid #cfd4dc; border-bottom: 1px solid #cfd4dc; }
.fit-list p { margin: 0; padding: 28px 26px; color: #343b49; }
.fit-list p + p { border-left: 1px solid #cfd4dc; }
.pro-cta { padding: 78px 0; text-align: center; }
.pro-cta h2 { margin: 0; color: var(--ink); font-size: 40px; letter-spacing: -.04em; }
.pro-cta p { margin: 12px 0 24px; color: var(--muted); }
.pro-cta small { display: block; margin-top: 12px; color: #8b929d; }

/* WeChat */
.wechat-widget { position: fixed; right: 0; top: 50%; z-index: 80; display: flex; align-items: center; transform: translateY(-45%); filter: drop-shadow(0 12px 26px rgba(16, 24, 40, .16)); }
.wechat-collapse { width: 42px; min-height: 176px; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 12px; padding: 14px 8px; color: #fff; background: var(--blue); border: 0; border-radius: 8px 0 0 8px; cursor: pointer; }
.wechat-collapse span { writing-mode: vertical-rl; letter-spacing: .12em; font-weight: 800; }
.wechat-collapse svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; transition: transform 180ms; }
.wechat-panel { width: 190px; padding: 14px 14px 16px; text-align: center; background: #fff; border: 1px solid #d5dae3; border-right: 0; border-radius: 10px 0 0 10px; }
.wechat-qr-crop { position: relative; width: 160px; height: 160px; overflow: hidden; margin: 0 auto 10px; background: #fff; }
.wechat-qr-crop img { position: absolute; top: -59.5%; left: -20.4%; width: 140.8%; max-width: none; height: auto; }
.wechat-panel strong, .wechat-panel span { display: block; color: var(--ink); }
.wechat-panel strong { font-size: 16px; }
.wechat-panel span { margin-top: 1px; color: var(--muted); font-size: 12px; }
.wechat-panel p { margin: 7px 0 0; color: #727987; font-size: 12px; }
.wechat-widget.is-collapsed .wechat-panel { display: none; }
.wechat-widget.is-collapsed .wechat-collapse svg { transform: rotate(180deg); }

.not-found { min-height: calc(100vh - 69px); display: grid; place-items: center; padding: 48px 24px; text-align: center; }
.not-found strong { color: var(--blue); }
.not-found h1 { margin: 5px 0; color: var(--ink); font-size: 90px; line-height: 1; }
.not-found p { margin: 12px 0 24px; color: var(--muted); }

@media (max-width: 1080px) {
  .library-page { grid-template-columns: 220px minmax(0, 1fr) 220px; }
  .library-sidebar { padding-left: 28px; padding-right: 28px; }
  .library-hero, .library-content { margin-left: 32px; margin-right: 32px; }
  .library-shell-page .wechat-widget { right: 12px; }
  .library-shell-page .wechat-panel { width: 168px; padding-left: 10px; padding-right: 10px; }
  .library-shell-page .wechat-qr-crop { width: 146px; height: 146px; }
  .document-row { grid-template-columns: 190px minmax(0, 1fr); gap: 24px; }
  .topic-grid { grid-template-columns: 1fr 1fr; }
  .pro-strip { grid-template-columns: 130px 1fr; }
  .pro-strip .button { grid-column: 2; justify-self: start; }
  .payment-note { margin-left: 182px; }
  .article-layout { grid-template-columns: 180px minmax(0, 1fr); gap: 38px; padding-right: 120px; }
}

@media (max-width: 860px) {
  .header-inner { grid-template-columns: auto 1fr auto; gap: 14px; }
  .nav-toggle { display: block; justify-self: end; }
  .site-nav { position: absolute; left: 0; right: 0; top: 68px; display: none; flex-direction: column; align-items: stretch; gap: 0; padding: 8px 24px 18px; background: #fff; border-bottom: 1px solid var(--line); box-shadow: var(--shadow); }
  .site-nav.is-open { display: flex; }
  .site-nav a { min-height: 46px; }
  .site-nav a::after { display: none; }
  .header-wechat { font-size: 0; width: 42px; padding: 0; }
  .header-wechat svg { width: 21px; height: 21px; }
  .library-shell-page .site-header { height: 68px; }
  .library-shell-page .header-inner { width: min(calc(100% - 48px), var(--max)); min-height: 68px; }
  .library-page { min-height: calc(100vh - 68px); grid-template-columns: 1fr; grid-template-rows: auto auto 1fr; grid-template-areas: "hero" "sidebar" "documents"; }
  .library-hero { margin: 0 24px; padding: 50px 0 32px; }
  .library-sidebar { padding: 0 24px; border-right: 0; border-bottom: 1px solid var(--line); }
  .library-sidebar .filter-row { display: flex; flex-wrap: wrap; gap: 8px; padding: 18px 0; }
  .library-sidebar .filter-button { width: auto; justify-self: auto; padding: 7px 12px; color: #656c79; background: #fff; border: 1px solid var(--line); border-radius: 4px; font-size: 14px; font-weight: 500; }
  .library-sidebar .filter-button::before { display: none; }
  .library-sidebar .filter-button:hover, .library-sidebar .filter-button.is-active { color: var(--blue); border-color: #9db2ff; background: #f6f8ff; }
  .library-content { margin: 0 24px; padding-bottom: 80px; }
  .library-wechat-rail { display: none; }
  .library-shell-page .wechat-widget { right: 0; top: 50%; transform: translateY(-45%); }
  .library-shell-page .wechat-panel { width: 180px; }
  .document-row { grid-template-columns: 210px minmax(0, 1fr); gap: 22px; }
  .portal-hero { padding-top: 54px; }
  .topic-rail { grid-template-columns: 1fr 1fr; }
  .topic-rail-item:nth-child(3), .topic-rail-item:nth-child(4) { border-top: 1px solid var(--line); }
  .topic-rail-item:nth-child(3)::before { display: none; }
  .featured-document { grid-template-columns: 240px 1fr; }
  .pro-strip ul { grid-template-columns: 1fr; }
  .article-layout { width: min(calc(100% - 40px), var(--reading)); display: block; padding: 42px 0 80px; }
  .article-toc { display: none; }
  .mobile-toc { display: block; margin: 24px 0 0; border: 1px solid var(--line); }
  .mobile-toc summary { padding: 13px 16px; color: var(--ink); font-weight: 750; cursor: pointer; }
  .mobile-toc nav { display: grid; padding: 0 16px 14px; }
  .mobile-toc a { padding: 5px 0; color: var(--blue); font-size: 14px; }
  .pro-hero .section-inner { grid-template-columns: 1fr; gap: 36px; }
  .pro-price-card { padding: 24px 0 0; border-left: 0; border-top: 1px solid var(--line); }
  .fit-list { grid-template-columns: 1fr; }
  .fit-list p + p { border-left: 0; border-top: 1px solid #cfd4dc; }
}

@media (max-width: 640px) {
  .section-inner, .header-inner, .site-footer-inner { width: min(calc(100% - 32px), var(--max)); }
  .header-inner { min-height: 64px; }
  .library-shell-page .site-header { height: 64px; }
  .library-shell-page .header-inner { width: min(calc(100% - 32px), var(--max)); min-height: 64px; }
  .site-nav { top: 64px; padding-left: 16px; padding-right: 16px; }
  .brand { font-size: 21px; }
  .home-hero { padding: 64px 0 52px; }
  .home-hero h1 { font-size: clamp(42px, 13vw, 58px); }
  .home-hero .section-inner > p:last-child { font-size: 17px; }
  .home-destinations { padding-bottom: 62px; }
  .home-destination { grid-template-columns: 42px minmax(0, 1fr); gap: 14px; padding: 26px 0; }
  .home-destination h2 { font-size: 23px; }
  .destination-action { grid-column: 2; justify-self: start; margin-top: 4px; }
  .library-hero { margin: 0 16px; padding: 46px 0 28px; }
  .library-sidebar { padding: 0 16px; }
  .library-content { margin: 0 16px; padding-bottom: 66px; }
  .document-row { grid-template-columns: 1fr; gap: 18px; padding: 26px 0 30px; }
  .document-row .document-cover { max-width: none; }
  .wechat-is-open .library-page .document-row .document-copy,
  .wechat-is-open .library-page .empty-state { padding-right: 148px; }
  .portal-hero h1 { font-size: clamp(42px, 13vw, 58px); }
  .portal-hero > .section-inner > p { font-size: 17px; }
  .topic-rail { margin-top: 36px; }
  .topic-rail-item { min-height: 58px; font-size: 14px; }
  .portal-section { padding-top: 34px; }
  .number-heading { gap: 12px; }
  .number-heading > span { font-size: 20px; }
  .number-heading h2 { font-size: 22px; }
  .filter-row, .featured-document, .empty-state, .topic-grid, .pro-strip, .benefit-rows, .fit-list { margin-left: 0; }
  .filter-row { flex-wrap: nowrap; overflow-x: auto; padding-bottom: 5px; }
  .filter-button { flex: 0 0 auto; }
  .library-toolbar .filter-row { flex-wrap: wrap; overflow: visible; padding-bottom: 0; }
  .featured-document { grid-template-columns: 1fr; gap: 22px; }
  .document-copy h3 { font-size: 26px; }
  .topic-grid { grid-template-columns: 1fr; gap: 10px; }
  .topic-card { min-height: 62px; }
  .pro-strip { grid-template-columns: 1fr; gap: 22px; }
  .pro-strip .button { grid-column: auto; justify-self: stretch; }
  .payment-note { margin-left: 0; }
  .site-footer-inner { grid-template-columns: 1fr; gap: 14px; }
  .footer-meta { order: 3; }
  .article-layout { width: min(calc(100% - 32px), var(--reading)); padding-top: 32px; }
  .article-header h1 { font-size: clamp(36px, 11vw, 48px); }
  .article-header > p { font-size: 16px; }
  .article-content > section { padding-top: 48px; }
  .article-content h2 { font-size: 26px; }
  .example-grid, .media-pair, .video-comparison, .face-grid { grid-template-columns: 1fr; }
  .responsibility-grid { grid-template-columns: 1fr; }
  .responsibility-grid > div + div { border-left: 0; border-top: 1px solid var(--line); }
  .code-block pre { max-height: 420px; padding-left: 16px; padding-right: 16px; }
  .article-callout { padding: 15px 16px; }
  .pro-hero { padding: 58px 0; }
  .pro-hero h1 { font-size: clamp(40px, 12vw, 54px); }
  .benefit-rows article { grid-template-columns: 48px 1fr; gap: 14px; }
  .benefit-rows h3 { font-size: 20px; }
  .pro-cta h2 { font-size: 32px; }
  .wechat-widget { top: auto; right: 4px; bottom: 12px; transform: none; align-items: flex-end; }
  .wechat-collapse { width: 34px; min-height: 124px; padding: 10px 6px; border-radius: 8px 0 0 8px; }
  .wechat-collapse span { font-size: 12px; }
  .wechat-panel { width: 144px; padding: 9px 9px 11px; border-right: 1px solid #d5dae3; border-radius: 9px 0 0 9px; }
  .wechat-qr-crop { width: 122px; height: 122px; margin-bottom: 7px; }
  .wechat-panel strong { font-size: 14px; }
  .wechat-panel p { margin-top: 4px; font-size: 10px; }
  .library-shell-page .wechat-widget { top: auto; right: 4px; bottom: 12px; transform: none; }
  .library-shell-page .wechat-collapse { width: 34px; min-height: 124px; padding: 10px 6px; }
  .library-shell-page .wechat-collapse span { display: block; }
  .library-shell-page .wechat-panel { width: 144px; padding: 9px 9px 11px; }
  .library-shell-page .wechat-title { margin-bottom: 7px; font-size: 14px; }
  .library-shell-page .wechat-qr-crop { width: 122px; height: 122px; }
  .not-found h1 { font-size: 72px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; }
}