:root {
    --bg: #edf1f5;
    --card: #fff;
    --line: #dbe3ec;
    --line-soft: #e8edf2;
    --navy: #122a46;
    --navy-2: #254666;
    --blue: #3f73b8;
    --blue-dark: #315f98;
    --blue-soft: #edf4fb;
    --teal: #15786f;
    --teal-soft: #eaf7f4;
    --orange: #ad6e13;
    --orange-soft: #fff7e8;
    --text: #1d2937;
    --muted: #68788b;
    --muted-2: #8996a5;
    --shadow: 0 4px 14px rgba(15, 35, 58, .05);
    --radius: 7px;
}

* { box-sizing: border-box; }
html { min-height: 100%; scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { min-height: 100%; margin: 0; padding-top: 66px; color: var(--text); background: var(--bg); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif; -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; -webkit-tap-highlight-color: transparent; }
button, input { font: inherit; }
button { -webkit-tap-highlight-color: transparent; }
.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; }

.site-app-header { position: fixed; inset: 0 0 auto; z-index: 100; width: 100%; background: rgba(255,255,255,.96); border-bottom: 1px solid #e2e8ef; box-shadow: 0 2px 10px rgba(15,35,58,.04); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); }
.site-app-header-inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; width: 100%; max-width: 750px; min-height: 66px; margin: 0 auto; padding: calc(env(safe-area-inset-top, 0px) + 10px) 14px 10px; }
.site-app-logo { display: flex; min-width: 0; flex: 1 1 auto; align-items: center; gap: 10px; }
.site-app-logo-box { width: 38px; height: 38px; flex: 0 0 auto; overflow: hidden; border-radius: 7px; }
.site-app-logo-box img { display: block; width: 100%; height: 100%; }
.site-app-logo-text { display: block; min-width: 0; }
.site-app-logo-text strong, .site-app-logo-text small { display: block; overflow: hidden; white-space: nowrap; text-overflow: ellipsis; }
.site-app-logo-text strong { color: var(--navy); font-size: 17px; font-weight: 750; line-height: 1.15; }
.site-app-logo-text small { margin-top: 3px; color: var(--muted); font-size: 11px; }
.page-nav-actions { display: inline-flex; flex: 0 0 auto; align-items: center; gap: 6px; }
.page-nav-button { display: inline-flex; min-width: 58px; min-height: 36px; align-items: center; justify-content: center; gap: 5px; padding: 0 9px; color: var(--blue-dark); background: #f8fafc; border: 1px solid #d4dfeb; border-radius: 6px; font-size: 12px; font-weight: 700; cursor: pointer; transition: background .15s ease, border-color .15s ease, transform .15s ease; }
.page-nav-button svg { width: 15px; height: 15px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.page-nav-button:hover { background: var(--blue-soft); border-color: #b7cadf; }
.page-nav-button:active { transform: translateY(1px); }
.page-nav-button:focus-visible, .help-search input:focus-visible, .help-search button:focus-visible, .category-card:focus-visible, .article-card:focus-visible { outline: 3px solid rgba(63,115,184,.2); outline-offset: 2px; }

.help-shell, .article-shell { width: 100%; max-width: 750px; margin: 0 auto; padding: 14px 12px 24px; }
.help-hero { position: relative; overflow: hidden; padding: 23px 20px 21px; color: #fff; background: linear-gradient(135deg, #102541 0%, #17395d 100%); border: 1px solid #294c70; border-radius: 8px; box-shadow: 0 8px 22px rgba(15,35,58,.12); }
.help-hero::after { content: "?"; position: absolute; right: 18px; top: -30px; color: rgba(255,255,255,.06); font-family: Georgia, serif; font-size: 180px; font-weight: 700; line-height: 1; pointer-events: none; }
.help-eyebrow, .section-kicker { display: block; color: #e8b956; font-size: 10px; font-weight: 800; letter-spacing: .15em; }
.help-hero h1 { position: relative; z-index: 1; margin: 7px 0 0; font-size: 25px; font-weight: 760; line-height: 1.28; }
.help-hero > p { position: relative; z-index: 1; max-width: 570px; margin: 8px 0 0; color: #c9d7e7; font-size: 13px; line-height: 1.65; }
.help-search { position: relative; z-index: 1; display: grid; grid-template-columns: 20px minmax(0,1fr) auto; align-items: center; gap: 8px; margin-top: 17px; padding: 5px 5px 5px 13px; background: #fff; border: 1px solid rgba(255,255,255,.45); border-radius: 7px; box-shadow: 0 5px 16px rgba(3,15,29,.16); }
.help-search svg { width: 18px; height: 18px; fill: none; stroke: #728399; stroke-width: 1.8; stroke-linecap: round; }
.help-search input { min-width: 0; height: 35px; padding: 0; color: var(--text); background: transparent; border: 0; outline: 0; font-size: 13px; }
.help-search input::placeholder { color: #929eab; }
.help-search button { min-width: 62px; height: 35px; padding: 0 12px; color: #fff; background: var(--blue); border: 0; border-radius: 5px; font-size: 12px; font-weight: 700; cursor: pointer; }
.help-search button:hover { background: var(--blue-dark); }
.quick-questions { position: relative; z-index: 1; display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.quick-question { padding: 5px 8px; color: #cbd9e7; background: rgba(255,255,255,.07); border: 1px solid rgba(255,255,255,.13); border-radius: 999px; font-size: 10px; cursor: pointer; }
.quick-question:hover { color: #fff; background: rgba(255,255,255,.12); }

.help-section { margin-top: 14px; padding: 15px; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.section-heading { display: flex; align-items: flex-end; justify-content: space-between; gap: 12px; margin-bottom: 12px; }
.section-heading h2, .article-toolbar h2 { margin: 3px 0 0; color: var(--navy); font-size: 18px; line-height: 1.25; }
.section-note { flex: 0 0 auto; color: var(--muted); font-size: 10.5px; }
.start-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 9px; }
.start-card { position: relative; min-width: 0; padding: 13px 12px 12px; background: #f7f9fc; border: 1px solid #dfe7ef; border-radius: 6px; transition: border-color .15s ease, background .15s ease, transform .15s ease; }
.start-card:hover { background: #f1f6fb; border-color: #bccfe2; transform: translateY(-1px); }
.start-number { display: grid; width: 24px; height: 24px; place-items: center; color: #fff; background: var(--blue); border-radius: 5px; font-size: 11px; font-weight: 800; }
.start-card strong { display: block; margin-top: 9px; color: var(--navy); font-size: 13px; line-height: 1.4; }
.start-card p { margin: 4px 0 0; color: var(--muted); font-size: 10.5px; line-height: 1.5; }
.start-card span:last-child { display: block; margin-top: 8px; color: var(--blue-dark); font-size: 10.5px; font-weight: 700; }

.category-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 8px; }
.category-card { display: flex; min-width: 0; min-height: 90px; align-items: flex-start; gap: 10px; padding: 12px; color: inherit; background: #fff; border: 1px solid var(--line-soft); border-radius: 6px; text-align: left; cursor: pointer; transition: border-color .15s ease, background .15s ease; }
.category-card:hover, .category-card.is-active { background: var(--blue-soft); border-color: #bcd0e4; }
.category-icon { display: grid; width: 32px; height: 32px; flex: 0 0 auto; place-items: center; color: var(--blue-dark); background: var(--blue-soft); border-radius: 6px; }
.category-icon svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }
.category-card strong { display: block; color: var(--navy); font-size: 12.5px; }
.category-card p { margin: 4px 0 0; color: var(--muted); font-size: 10px; line-height: 1.45; }
.category-count { display: block; margin-top: 5px; color: var(--blue-dark); font-size: 9.5px; }

.article-toolbar { display: flex; align-items: flex-end; justify-content: space-between; gap: 12px; margin-bottom: 10px; }
.filter-reset { min-height: 30px; padding: 0 9px; color: var(--blue-dark); background: var(--blue-soft); border: 1px solid #ccdaea; border-radius: 5px; font-size: 10.5px; cursor: pointer; }
.active-filter { margin: -2px 0 10px; padding: 7px 9px; color: #475d75; background: #f4f7fa; border-left: 3px solid var(--blue); font-size: 11px; }
.article-list { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 8px; }
.article-card { display: flex; min-width: 0; min-height: 118px; flex-direction: column; padding: 12px; background: #fff; border: 1px solid var(--line-soft); border-radius: 6px; transition: border-color .15s ease, box-shadow .15s ease, transform .15s ease; }
.article-card:hover { border-color: #b9cde1; box-shadow: 0 4px 12px rgba(25,62,98,.06); transform: translateY(-1px); }
.article-card-top { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.article-card-category { color: var(--blue-dark); font-size: 9.5px; font-weight: 750; }
.article-card-time { color: var(--muted-2); font-size: 9px; }
.article-card h3 { margin: 7px 0 0; color: var(--navy); font-size: 13px; line-height: 1.45; }
.article-card p { margin: 5px 0 0; color: var(--muted); font-size: 10.5px; line-height: 1.5; }
.article-card-keywords { display: flex; flex-wrap: wrap; gap: 4px; margin-top: auto; padding-top: 8px; }
.article-card-keywords span { padding: 3px 5px; color: #66788b; background: #f4f6f8; border-radius: 3px; font-size: 8.5px; }
.help-empty { padding: 34px 16px; color: var(--muted); text-align: center; }
.help-empty svg { width: 36px; height: 36px; fill: none; stroke: #9aa8b6; stroke-width: 1.5; }
.help-empty strong { display: block; margin-top: 8px; color: var(--navy); font-size: 14px; }
.help-empty p { margin: 5px 0 0; font-size: 11px; }

.help-principle { display: flex; align-items: flex-start; gap: 11px; margin-top: 14px; padding: 13px 14px; background: #fffaf1; border: 1px solid #eadbc1; border-radius: 6px; }
.principle-icon { display: grid; width: 30px; height: 30px; flex: 0 0 auto; place-items: center; color: var(--orange); background: var(--orange-soft); border-radius: 6px; }
.principle-icon svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }
.help-principle strong { color: #6e4a16; font-size: 12px; }
.help-principle p { margin: 3px 0 0; color: #806842; font-size: 10.5px; line-height: 1.55; }

.site-footer { width: 100%; max-width: 750px; margin: 0 auto; padding: 16px 12px calc(22px + env(safe-area-inset-bottom)); color: var(--muted); text-align: center; font-size: 10.5px; }
.footer-links { display: flex; justify-content: center; flex-wrap: wrap; gap: 6px; }
.footer-links a:hover { color: var(--blue-dark); }
.site-footer p { margin: 6px 0 0; }
.back-to-top { position: fixed; z-index: 60; right: max(12px, calc((100vw - 750px) / 2 + 12px)); bottom: calc(18px + env(safe-area-inset-bottom)); display: grid; width: 38px; height: 38px; place-items: center; color: var(--blue-dark); background: #fff; border: 1px solid #cbd8e5; border-radius: 6px; box-shadow: 0 5px 14px rgba(15,35,58,.1); opacity: 0; pointer-events: none; transform: translateY(8px); transition: opacity .15s ease, transform .15s ease; cursor: pointer; }
.back-to-top.show { opacity: 1; pointer-events: auto; transform: translateY(0); }
.back-to-top svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }

/* Article */
.breadcrumb { display: flex; align-items: center; gap: 6px; overflow: hidden; margin: 2px 2px 10px; color: var(--muted); font-size: 10.5px; white-space: nowrap; }
.breadcrumb a { color: var(--blue-dark); }
.breadcrumb span:last-child { overflow: hidden; text-overflow: ellipsis; }
.article-layout { display: grid; grid-template-columns: minmax(0,1fr) 190px; align-items: start; gap: 12px; }
.help-article { overflow: hidden; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.article-header { padding: 21px 20px 18px; background: #fff; border-bottom: 1px solid var(--line-soft); }
.article-category { color: var(--blue-dark); font-size: 10px; font-weight: 800; letter-spacing: .08em; }
.article-header h1 { margin: 7px 0 0; color: var(--navy); font-size: 24px; line-height: 1.35; }
.article-header > p { margin: 8px 0 0; color: var(--muted); font-size: 12.5px; line-height: 1.65; }
.article-meta { display: flex; flex-wrap: wrap; gap: 6px 12px; margin-top: 11px; color: var(--muted-2); font-size: 9.5px; }
.open-feature-link { display: inline-flex; min-height: 34px; align-items: center; gap: 5px; margin-top: 13px; padding: 0 11px; color: var(--blue-dark); background: var(--blue-soft); border: 1px solid #cadced; border-radius: 5px; font-size: 11px; font-weight: 700; }
.open-feature-link svg { width: 14px; height: 14px; fill: none; stroke: currentColor; stroke-width: 1.7; }
.article-takeaway { margin: 14px 18px 0; padding: 11px 12px; color: #285c57; background: var(--teal-soft); border-left: 3px solid var(--teal); border-radius: 4px; font-size: 11.5px; line-height: 1.6; }
.article-takeaway strong { display: block; margin-bottom: 3px; color: #175f58; }
.article-content { padding: 4px 20px 22px; }
.article-section-block { padding-top: 18px; }
.article-section-block h2 { scroll-margin-top: 82px; margin: 0; color: var(--navy); font-size: 17px; line-height: 1.4; }
.article-section-block > p { margin: 7px 0 0; color: #506174; font-size: 12px; line-height: 1.75; }
.step-list { display: grid; gap: 8px; margin-top: 11px; padding: 0; list-style: none; }
.step-item { display: grid; grid-template-columns: 25px minmax(0,1fr); gap: 9px; padding: 10px; background: #f8fafc; border: 1px solid #e3e9ef; border-radius: 5px; }
.step-number { display: grid; width: 25px; height: 25px; place-items: center; color: #fff; background: var(--blue); border-radius: 5px; font-size: 10px; font-weight: 800; }
.step-item strong { display: block; color: var(--navy); font-size: 12px; }
.step-item p { margin: 3px 0 0; color: var(--muted); font-size: 11px; line-height: 1.6; }
.plain-list { display: grid; gap: 7px; margin: 9px 0 0; padding: 0; list-style: none; }
.plain-list li { position: relative; padding-left: 15px; color: #526274; font-size: 11.5px; line-height: 1.65; }
.plain-list li::before { content: ""; position: absolute; left: 2px; top: .72em; width: 5px; height: 5px; background: var(--blue); border-radius: 50%; }
.definition-list { display: grid; gap: 7px; margin-top: 10px; }
.definition-item { padding: 9px 10px; background: #fbfcfd; border: 1px solid #e5eaf0; border-radius: 5px; }
.definition-item strong { display: block; color: var(--navy-2); font-size: 11.5px; }
.definition-item p { margin: 3px 0 0; color: var(--muted); font-size: 10.8px; line-height: 1.6; }
.note-box { margin-top: 10px; padding: 10px 11px; color: #73541f; background: var(--orange-soft); border: 1px solid #ecd8b4; border-radius: 5px; font-size: 11px; line-height: 1.65; }
.note-box strong { color: #65450d; }
.article-aside { position: sticky; top: 78px; display: grid; gap: 9px; }
.toc-card, .aside-tip { padding: 12px; background: #fff; border: 1px solid var(--line); border-radius: 6px; box-shadow: var(--shadow); }
.toc-card > strong, .aside-tip > strong { color: var(--navy); font-size: 11.5px; }
.toc-card nav { display: grid; gap: 3px; margin-top: 8px; }
.toc-card a { padding: 6px 7px; color: var(--muted); border-left: 2px solid transparent; font-size: 10px; line-height: 1.35; }
.toc-card a:hover { color: var(--blue-dark); background: var(--blue-soft); border-left-color: var(--blue); }
.aside-tip { background: #fffaf2; border-color: #eadfc9; }
.aside-tip p { margin: 5px 0 0; color: #806d4b; font-size: 10px; line-height: 1.55; }
.aside-tip a { display: block; margin-top: 7px; color: #92611a; font-size: 10px; font-weight: 700; }
.article-neighbors { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 8px; margin-top: 12px; }
.neighbor-link { padding: 10px 11px; background: #fff; border: 1px solid var(--line); border-radius: 6px; }
.neighbor-link.next { text-align: right; }
.neighbor-link span { display: block; color: var(--muted-2); font-size: 9px; }
.neighbor-link strong { display: block; overflow: hidden; margin-top: 3px; color: var(--navy-2); font-size: 11px; text-overflow: ellipsis; white-space: nowrap; }
.related-guides { margin-top: 12px; padding: 14px; background: #fff; border: 1px solid var(--line); border-radius: 7px; }
.related-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 7px; }
.related-card { padding: 10px; background: #f8fafc; border: 1px solid #e4eaf0; border-radius: 5px; }
.related-card span { color: var(--blue-dark); font-size: 9px; }
.related-card strong { display: block; margin-top: 4px; color: var(--navy); font-size: 11px; line-height: 1.45; }
.article-not-found { padding: 50px 20px; background: #fff; border: 1px solid var(--line); border-radius: 7px; text-align: center; }
.article-not-found h1 { color: var(--navy); font-size: 21px; }
.article-not-found p { color: var(--muted); font-size: 12px; }
.article-not-found a { display: inline-flex; margin-top: 8px; padding: 8px 12px; color: #fff; background: var(--blue); border-radius: 5px; font-size: 11px; }

@media (max-width: 640px) {
    body { padding-top: 58px; }
    .site-app-header-inner { min-height: 58px; padding: calc(env(safe-area-inset-top, 0px) + 8px) 9px 8px; }
    .site-app-logo-box { width: 34px; height: 34px; }
    .site-app-logo-text strong { font-size: 15px; }
    .site-app-logo-text small { font-size: 10px; }
    .page-nav-button { min-width: 50px; min-height: 34px; padding: 0 7px; }
    .page-nav-button span { display: none; }
    .page-nav-button svg { width: 17px; height: 17px; }
    .help-shell, .article-shell { padding: 8px 6px 16px; }
    .help-hero { padding: 18px 13px 16px; }
    .help-hero h1 { font-size: 21px; }
    .help-hero > p { font-size: 12px; }
    .help-search { grid-template-columns: 18px minmax(0,1fr); padding: 5px 10px; }
    .help-search input { height: 38px; font-size: 16px; }
    .help-search button { display: none; }
    .help-section { margin-top: 9px; padding: 11px; }
    .section-heading { align-items: flex-start; }
    .section-heading h2, .article-toolbar h2 { font-size: 16px; }
    .section-note { max-width: 120px; text-align: right; }
    .start-grid, .category-grid, .article-list { grid-template-columns: 1fr; }
    .start-card { display: grid; grid-template-columns: 26px minmax(0,1fr); column-gap: 9px; min-height: 0; }
    .start-card strong, .start-card p, .start-card span:last-child { grid-column: 2; margin-top: 0; }
    .start-card p { margin-top: 3px; }
    .start-card span:last-child { margin-top: 5px; }
    .category-card { min-height: 0; }
    .article-card { min-height: 0; }
    .help-principle { margin-top: 9px; }
    .back-to-top { right: 9px; bottom: calc(12px + env(safe-area-inset-bottom)); }

    .breadcrumb { margin: 3px 3px 8px; }
    .article-layout { display: block; }
    .article-aside { position: static; margin-bottom: 9px; }
    .toc-card { display: none; }
    .aside-tip { padding: 10px; }
    .help-article { border-radius: 6px; }
    .article-header { padding: 17px 14px 14px; }
    .article-header h1 { font-size: 21px; }
    .article-header > p { font-size: 12px; }
    .article-takeaway { margin: 11px 12px 0; }
    .article-content { padding: 2px 14px 18px; }
    .article-section-block { padding-top: 16px; }
    .article-section-block h2 { font-size: 16px; }
    .article-neighbors { grid-template-columns: 1fr; }
    .neighbor-link.next { text-align: left; }
    .related-guides { padding: 11px; }
    .related-grid { grid-template-columns: 1fr; }
}

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