:root{
  --brand:#2f6f68;
  --brand-dark:#173f3b;
  --brand-soft:#e5efeb;
  --ink:#15211f;
  --text:#42504d;
  --muted:#78827f;
  --line:#dfe6e2;
  --surface:#ffffff;
  --surface-soft:#f4f7f4;
  --surface-deep:#edf2ef;
  --shadow-sm:0 8px 24px rgba(18,49,44,.06);
  --shadow-md:0 20px 55px rgba(18,49,44,.09);
  --radius-sm:12px;
  --radius:18px;
  --radius-lg:28px;
  --max:1180px;
  --font:"PingFang SC","Microsoft YaHei","微软雅黑","Hiragino Sans GB",-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:var(--font);color:var(--ink);background:var(--surface);line-height:1.7;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
button,input{font:inherit}
svg{display:block}
img{display:block;max-width:100%}
.container{width:min(var(--max),calc(100% - 48px));margin:0 auto}
.icon{width:22px;height:22px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}

/* Header */
.site-header{position:sticky;top:0;z-index:40;padding:14px 0;background:rgba(250,252,250,.86);backdrop-filter:blur(18px) saturate(1.2);border-bottom:1px solid rgba(223,230,226,.78)}
.header-inner{height:58px;display:flex;align-items:center;gap:24px;padding:0 17px 0 20px;background:rgba(255,255,255,.82);border:1px solid rgba(31,65,59,.09);border-radius:17px;box-shadow:var(--shadow-sm)}
.brand{display:flex;align-items:center;gap:10px;white-space:nowrap}
.brand-logo{height:21px;width:auto}
.brand-sub{font-weight:600;color:var(--muted);font-size:13px;padding-left:10px;border-left:1px solid #d9e1dd}
.header-spacer{flex:1}
.header-link{font-size:14px;color:#53605d;font-weight:600;padding:8px 11px;border-radius:9px;transition:.2s}
.header-link:hover{background:var(--surface-deep);color:var(--brand-dark)}
.header-cta{display:inline-flex;align-items:center;gap:8px;padding:9px 14px;border-radius:10px;background:var(--brand-dark);color:#fff;font-size:14px;font-weight:700;transition:.2s}
.header-cta:hover{background:#0e312d;transform:translateY(-1px)}

/* Search */
.search-wrap{position:relative;width:100%;max-width:720px}
.search-box{display:flex;align-items:center;gap:12px;width:100%;height:62px;padding:0 19px;background:#fff;border:1px solid #d8e2dd;border-radius:16px;box-shadow:0 18px 48px rgba(16,52,46,.10);transition:.2s}
.search-box:focus-within{border-color:#88aaa2;box-shadow:0 22px 58px rgba(16,52,46,.15),0 0 0 4px rgba(47,111,104,.08)}
.search-box .icon{color:#6a7774;flex:none}
.search-box input{width:100%;border:0;outline:0;background:transparent;color:var(--ink);font-size:16px}
.search-box input::placeholder{color:#98a19f}
.search-shortcut{flex:none;padding:4px 8px;border:1px solid #dfe5e2;border-radius:7px;background:#f7f9f7;color:#88918f;font-size:12px}
.search-results{display:none;position:absolute;left:0;right:0;top:70px;padding:8px;background:#fff;border:1px solid var(--line);border-radius:15px;box-shadow:var(--shadow-md);z-index:30;max-height:360px;overflow:auto}
.search-results.open{display:block}
.search-result{display:flex;align-items:flex-start;gap:12px;padding:12px;border-radius:11px;transition:.18s}
.search-result:hover,.search-result.active{background:var(--surface-soft)}
.search-result-icon{width:34px;height:34px;border-radius:9px;background:var(--brand-soft);color:var(--brand-dark);display:grid;place-items:center;flex:none}
.search-result-icon .icon{width:17px;height:17px}
.search-result b{display:block;font-size:14px;line-height:1.45}
.search-result span{display:block;margin-top:3px;font-size:12px;color:var(--muted)}
.search-empty{padding:22px;text-align:center;color:var(--muted);font-size:14px}
.compact-search{max-width:430px;margin-left:auto}
.compact-search .search-box{height:42px;border-radius:11px;box-shadow:none;padding:0 13px;background:#f7f9f7}
.compact-search .search-box input{font-size:14px}
.compact-search .search-results{top:49px}

/* Home hero */
.help-hero{position:relative;overflow:hidden;padding:82px 0 90px;background:linear-gradient(180deg,#f7faf7 0%,#eef4f0 100%);border-bottom:1px solid #e2e9e5}
.help-hero::before{content:"";position:absolute;inset:0;background-image:linear-gradient(rgba(31,78,70,.035) 1px,transparent 1px),linear-gradient(90deg,rgba(31,78,70,.035) 1px,transparent 1px);background-size:54px 54px;-webkit-mask-image:linear-gradient(to bottom,black,transparent 92%);mask-image:linear-gradient(to bottom,black,transparent 92%)}
.help-hero::after{content:"";position:absolute;width:720px;height:420px;left:50%;top:-240px;transform:translateX(-50%);border-radius:50%;background:radial-gradient(circle,rgba(71,139,127,.22),transparent 66%);filter:blur(20px)}
.hero-content{position:relative;z-index:1;display:flex;flex-direction:column;align-items:center;text-align:center}
.eyebrow{display:inline-flex;align-items:center;gap:8px;margin-bottom:18px;padding:7px 12px;border-radius:999px;background:rgba(255,255,255,.72);border:1px solid #d7e3de;color:var(--brand-dark);font-size:12px;font-weight:800;letter-spacing:.08em}
.eyebrow-dot{width:7px;height:7px;border-radius:50%;background:#3aa27e}
.help-hero h1{margin:0 0 15px;font-size:clamp(36px,5vw,56px);line-height:1.12;letter-spacing:-.055em}
.help-hero p{max-width:640px;margin:0 0 32px;color:#63706d;font-size:17px}
.popular-links{display:flex;justify-content:center;flex-wrap:wrap;gap:9px;margin-top:20px;color:#5e6a67;font-size:13px}
.popular-links span{color:#8a9491}
.popular-links a{padding:5px 9px;border-radius:7px;transition:.18s}
.popular-links a:hover{background:rgba(255,255,255,.8);color:var(--brand-dark)}

/* Shared section */
.section{padding:76px 0}
.section.soft{background:var(--surface-soft)}
.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:24px;margin-bottom:30px}
.section-head h2{margin:0;font-size:29px;letter-spacing:-.035em}
.section-head p{margin:8px 0 0;color:var(--muted);font-size:14px}
.section-head a{color:var(--brand);font-size:14px;font-weight:700}

/* Home categories */
.category-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:17px}
.category-card{position:relative;min-height:255px;padding:25px;border:1px solid var(--line);border-radius:21px;background:#fff;transition:.25s;overflow:hidden}
.category-card::after{content:"";position:absolute;width:130px;height:130px;right:-48px;bottom:-58px;border-radius:50%;background:radial-gradient(circle,rgba(54,118,107,.12),transparent 70%);transition:.3s}
.category-card:hover{transform:translateY(-4px);border-color:#bdd0c9;box-shadow:var(--shadow-md)}
.category-card:hover::after{transform:scale(1.35)}
.category-top{display:flex;align-items:flex-start;justify-content:space-between;gap:18px;margin-bottom:18px}
.category-icon{width:45px;height:45px;border-radius:13px;display:grid;place-items:center;background:var(--brand-soft);color:var(--brand-dark)}
.category-icon .icon{width:21px;height:21px}
.category-count{color:#929b98;font-size:12px}
.category-card h3{margin:0 0 7px;font-size:18px;letter-spacing:-.02em}
.category-card>p{margin:0 0 16px;color:var(--muted);font-size:13px;line-height:1.65}
.article-preview{display:flex;flex-direction:column;gap:9px;position:relative;z-index:1}
.article-preview a,.article-preview span{display:flex;align-items:center;gap:8px;color:#4c5956;font-size:13px;line-height:1.45}
.article-preview a::before,.article-preview span::before{content:"";width:4px;height:4px;border-radius:50%;background:#93a49f;flex:none}
.article-preview a:hover{color:var(--brand-dark)}
.category-more{display:flex;align-items:center;gap:5px;margin-top:16px;color:var(--brand);font-size:13px;font-weight:700}
.category-more .icon{width:15px;height:15px}

/* Popular panel */
.popular-panel{display:grid;grid-template-columns:1.1fr .9fr;gap:22px}
.article-list-card,.contact-card{border:1px solid var(--line);border-radius:22px;background:#fff}
.article-list-card{padding:9px 27px}
.article-row{display:flex;align-items:center;gap:15px;padding:17px 0;border-bottom:1px solid #e8edea}
.article-row:last-child{border-bottom:0}
.article-row-num{width:28px;height:28px;border-radius:8px;display:grid;place-items:center;background:#eef3f0;color:#60706c;font-size:12px;font-weight:800;flex:none}
.article-row-main{min-width:0;flex:1}
.article-row b{display:block;font-size:14px}
.article-row span{display:block;color:var(--muted);font-size:12px;margin-top:3px}
.article-row .icon{width:17px;height:17px;color:#9ca5a3;flex:none}
.article-row:hover b{color:var(--brand)}
.contact-card{position:relative;overflow:hidden;padding:31px;background:linear-gradient(145deg,#173f3b,#2f6f68);color:#fff}
.contact-card::after{content:"";position:absolute;width:280px;height:280px;right:-120px;bottom:-150px;border-radius:50%;background:radial-gradient(circle,rgba(255,255,255,.20),transparent 68%)}
.contact-icon{width:47px;height:47px;border-radius:13px;display:grid;place-items:center;background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.16);margin-bottom:34px}
.contact-card h3{margin:0 0 11px;font-size:24px;letter-spacing:-.035em}
.contact-card p{margin:0 0 22px;color:#c9dbd6;font-size:14px;max-width:420px}
.contact-card a{position:relative;z-index:1;display:inline-flex;align-items:center;gap:8px;padding:11px 15px;border-radius:10px;background:#fff;color:var(--brand-dark);font-size:14px;font-weight:800}

/* Interior hero */
.inner-hero{padding:43px 0 47px;background:linear-gradient(180deg,#f8faf8,#f2f6f3);border-bottom:1px solid #e2e8e4}
.inner-top{display:flex;align-items:center;gap:28px}
.inner-heading{min-width:0;flex:1}
.breadcrumbs{display:flex;align-items:center;flex-wrap:wrap;gap:7px;margin-bottom:15px;color:#77827f;font-size:13px}
.breadcrumbs a:hover{color:var(--brand)}
.breadcrumbs .icon{width:13px;height:13px}
.inner-heading h1{margin:0;font-size:clamp(32px,4vw,46px);line-height:1.18;letter-spacing:-.05em}
.inner-heading p{margin:11px 0 0;color:#67736f;font-size:15px}

/* Collection + FAQ accordion */
.collection-layout{display:grid;grid-template-columns:235px minmax(0,1fr);gap:48px;padding:55px 0 90px}
.collection-side{align-self:start;position:sticky;top:105px}
.side-title{margin-bottom:10px;color:#89938f;font-size:11px;font-weight:800;letter-spacing:.1em;text-transform:uppercase}
.side-nav{display:flex;flex-direction:column;gap:4px}
.side-nav a{padding:9px 11px;border-radius:9px;color:#596562;font-size:14px;font-weight:600}
.side-nav a:hover{background:var(--surface-soft);color:var(--brand-dark)}
.side-nav a.active{background:var(--brand-soft);color:var(--brand-dark)}
.collection-main{min-width:0}
.collection-group{margin-bottom:42px;scroll-margin-top:115px}
.group-head{display:flex;align-items:end;justify-content:space-between;gap:16px;margin-bottom:14px}
.group-head h2{margin:0;font-size:22px;letter-spacing:-.025em}
.group-head span{color:#929b98;font-size:12px}
.faq-item{border:1px solid var(--line);border-radius:14px;background:#fff;margin-bottom:10px;transition:border-color .2s,box-shadow .2s}
.faq-item:hover{border-color:#cfddd7}
.faq-item.open{border-color:#bcd0c9;box-shadow:var(--shadow-sm)}
.faq-q{display:flex;align-items:center;gap:14px;width:100%;padding:17px 19px;background:none;border:0;text-align:left;cursor:pointer;color:var(--ink)}
.faq-q-icon{width:37px;height:37px;border-radius:10px;background:#edf3f0;color:#486d66;display:grid;place-items:center;flex:none}
.faq-q-icon .icon{width:18px;height:18px}
.faq-q b{flex:1;font-size:15px;font-weight:600;line-height:1.5}
.faq-q .chev{width:18px;height:18px;color:#9aa4a1;flex:none;transition:transform .25s,color .2s}
.faq-item.open .faq-q .chev{transform:rotate(90deg);color:var(--brand)}
.faq-a{display:grid;grid-template-rows:0fr;transition:grid-template-rows .3s ease}
.faq-item.open .faq-a{grid-template-rows:1fr}
.faq-a-clip{overflow:hidden}
.faq-a-inner{padding:0 20px 20px 70px;color:#495652;font-size:14.5px;line-height:1.85}
.faq-a-inner>*:first-child{margin-top:0}
.faq-a-inner p{margin:0 0 10px}
.faq-a-inner ul,.faq-a-inner ol{margin:6px 0 12px;padding-left:20px}
.faq-a-inner li{margin:5px 0}
.faq-a-inner strong{color:#1c2b28}
.faq-a-inner a{color:var(--brand);text-decoration:underline;text-underline-offset:2px}
.faq-a-inner code{background:#eef3f0;padding:1px 6px;border-radius:6px;font-family:ui-monospace,Consolas,monospace;font-size:12.5px;color:#2c463f}
.faq-a-inner .mode-table{width:100%;border-collapse:separate;border-spacing:0;margin:4px 0 12px;border:1px solid var(--line);border-radius:12px;overflow:hidden;font-size:13.5px}
.faq-a-inner .mode-table th,.faq-a-inner .mode-table td{text-align:left;padding:10px 13px;border-bottom:1px solid var(--line)}
.faq-a-inner .mode-table th{width:34%;background:#f5f8f5;color:#3f4d49;font-weight:700}
.faq-a-inner .mode-table tr:last-child th,.faq-a-inner .mode-table tr:last-child td{border-bottom:0}

/* Article */
.article-layout{display:grid;grid-template-columns:minmax(0,760px) 245px;justify-content:center;gap:72px;padding:58px 0 86px}
.article-body{min-width:0}
.article-meta{display:flex;align-items:center;gap:9px;margin:14px 0 35px;color:#89928f;font-size:13px}
.article-meta-dot{width:3px;height:3px;border-radius:50%;background:#a2aaa8}
.article-body h1{margin:0;font-size:clamp(34px,4.2vw,49px);line-height:1.16;letter-spacing:-.05em}
.article-body h2{scroll-margin-top:110px;margin:46px 0 15px;font-size:25px;line-height:1.3;letter-spacing:-.03em}
.article-body h3{scroll-margin-top:110px;margin:29px 0 10px;font-size:18px;letter-spacing:-.018em}
.article-body p{margin:0 0 17px;color:#42504d;font-size:16px;line-height:1.9}
.article-body ul,.article-body ol{margin:0 0 22px;padding-left:25px;color:#42504d}
.article-body li{margin:8px 0;padding-left:3px}
.article-body strong{color:#1c2b28}
.article-body a{color:var(--brand);text-decoration:underline;text-underline-offset:3px}
.article-body hr{border:0;border-top:1px solid #e1e7e3;margin:42px 0}
.notice{display:flex;align-items:flex-start;gap:13px;margin:24px 0;padding:17px 18px;border:1px solid #cfe0da;border-radius:14px;background:#eff6f2;color:#35534d}
.notice.warning{background:#fbf7ed;border-color:#ebe0c4;color:#655938}
.notice .icon{width:20px;height:20px;flex:none;margin-top:2px}
.notice p{margin:0;font-size:14px;line-height:1.7;color:inherit}
.steps-list{counter-reset:articleStep;display:flex;flex-direction:column;gap:13px;margin:22px 0 26px}
.steps-list>div{counter-increment:articleStep;display:grid;grid-template-columns:31px 1fr;gap:13px;align-items:start;padding:16px 17px;border:1px solid var(--line);border-radius:13px;background:#fafcfa}
.steps-list>div::before{content:counter(articleStep);width:29px;height:29px;border-radius:8px;display:grid;place-items:center;background:var(--brand-dark);color:#fff;font-size:13px;font-weight:800}
.steps-list b{display:block;margin-bottom:3px;font-size:14px}
.steps-list p{margin:0;font-size:13px;line-height:1.65;color:#6b7773}
.spec-table{width:100%;border-collapse:separate;border-spacing:0;margin:21px 0 27px;border:1px solid var(--line);border-radius:14px;overflow:hidden;font-size:14px}
.spec-table th,.spec-table td{text-align:left;padding:13px 15px;border-bottom:1px solid var(--line)}
.spec-table th{width:32%;background:#f5f8f5;color:#4c5956;font-weight:700}
.spec-table tr:last-child th,.spec-table tr:last-child td{border-bottom:0}
.code-line{display:block;padding:14px 16px;border-radius:11px;background:#172421;color:#d9ebe6;font-family:ui-monospace,SFMono-Regular,Consolas,monospace;font-size:13px;overflow:auto}
.article-side{align-self:start;position:sticky;top:108px}
.toc-card{padding:17px;border:1px solid var(--line);border-radius:16px;background:#fafcfa}
.toc-title{margin-bottom:10px;font-size:12px;font-weight:800;color:#87908e;letter-spacing:.08em}
.toc{display:flex;flex-direction:column;gap:3px}
.toc a{padding:7px 9px;border-left:2px solid transparent;color:#68736f;font-size:13px;line-height:1.45}
.toc a:hover{color:var(--brand-dark)}
.toc a.active{border-left-color:var(--brand);color:var(--brand-dark);background:#eef4f1;border-radius:0 7px 7px 0;font-weight:700}
.feedback{margin-top:18px;padding:18px;border:1px solid var(--line);border-radius:16px;text-align:center}
.feedback p{margin:0 0 11px;font-size:13px;color:#5f6c68}
.feedback-actions{display:flex;justify-content:center;gap:8px}
.feedback button{width:40px;height:36px;border:1px solid var(--line);border-radius:9px;background:#fff;color:#60706c;cursor:pointer;transition:.18s}
.feedback button:hover,.feedback button.selected{background:var(--brand-soft);border-color:#bfd2cb;color:var(--brand-dark)}
.related{margin-top:42px;padding-top:34px;border-top:1px solid var(--line)}
.related h2{margin:0 0 15px;font-size:20px}
.related-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.related-card{display:flex;align-items:center;justify-content:space-between;gap:18px;padding:16px 17px;border:1px solid var(--line);border-radius:13px;background:#fff;transition:.18s}
.related-card:hover{border-color:#bfd1ca;background:#f9fbf9}
.related-card b{font-size:13px;line-height:1.5}
.related-card .icon{width:16px;height:16px;color:#9aa4a1;flex:none}

/* Footer */
.site-footer{padding:48px 0 25px;background:#172421;color:#9bb0aa}
.footer-top{display:flex;align-items:flex-start;justify-content:space-between;gap:30px;padding-bottom:30px;border-bottom:1px solid rgba(255,255,255,.08)}
.footer-brand .brand{margin-bottom:12px}
.footer-brand .brand-sub{color:#c7d6d1;border-left-color:rgba(255,255,255,.2)}
.footer-brand p{max-width:420px;margin:0;color:#92a7a2;font-size:13px}
.footer-links{display:flex;gap:45px}
.footer-links h4{margin:0 0 10px;color:#dbe7e3;font-size:12px;letter-spacing:.07em}
.footer-links a{display:block;margin:7px 0;color:#95aaa4;font-size:13px}
.footer-links a:hover{color:#fff}
.footer-bottom{display:flex;justify-content:space-between;gap:20px;padding-top:22px;color:#6f8680;font-size:12px}
.footer-bottom a{color:#88a09a;border-bottom:1px solid rgba(136,160,154,.35);transition:.2s}
.footer-bottom a:hover{color:#cfe0db;border-color:#cfe0db}

/* Toast */
.toast{position:fixed;left:50%;bottom:28px;z-index:80;transform:translate(-50%,18px);padding:10px 15px;border-radius:10px;background:#173f3b;color:#fff;font-size:13px;opacity:0;pointer-events:none;transition:.25s;box-shadow:var(--shadow-md)}
.toast.show{opacity:1;transform:translate(-50%,0)}

@media(max-width:980px){
  .category-grid{grid-template-columns:repeat(2,1fr)}
  .popular-panel{grid-template-columns:1fr}
  .collection-layout{grid-template-columns:1fr;gap:25px}
  .collection-side{position:static;overflow:auto;margin:0 -24px;padding:0 24px}
  .side-title{display:none}
  .side-nav{flex-direction:row;width:max-content}
  .side-nav a{white-space:nowrap;background:#f5f7f5}
  .article-layout{grid-template-columns:minmax(0,760px);gap:0}
  .article-side{display:none}
}
@media(max-width:760px){
  .container{width:min(100% - 32px,var(--max))}
  .site-header{padding:9px 0}
  .header-inner{height:54px;padding:0 12px;gap:12px}
  .brand-sub,.header-link{display:none}
  .header-cta{padding:8px 10px;font-size:0;gap:0}
  .header-cta .icon{width:18px;height:18px}
  .compact-search{display:none}
  .help-hero{padding:60px 0 66px}
  .help-hero h1{font-size:38px}
  .help-hero p{font-size:15px}
  .search-box{height:57px;padding:0 15px}
  .search-shortcut{display:none}
  .category-grid{grid-template-columns:1fr}
  .category-card{min-height:0}
  .section{padding:56px 0}
  .section-head{align-items:flex-start;flex-direction:column;margin-bottom:22px}
  .section-head h2{font-size:26px}
  .inner-hero{padding:29px 0 34px}
  .inner-top{display:block}
  .inner-heading h1{font-size:34px}
  .collection-layout{padding:35px 0 65px}
  .faq-q{padding:15px}
  .faq-q b{font-size:14px}
  .article-layout{padding:38px 0 64px}
  .article-body h1{font-size:36px}
  .article-body h2{font-size:23px}
  .article-body p{font-size:15px}
  .related-grid{grid-template-columns:1fr}
  .footer-top{flex-direction:column}
  .footer-links{gap:30px;flex-wrap:wrap}
  .footer-bottom{flex-direction:column}
}
@media(max-width:480px){
  .container{width:min(100% - 24px,var(--max))}
  .header-inner{border-radius:14px}
  .brand-logo{height:19px}
  .help-hero h1{font-size:34px}
  .popular-links{display:none}
  .category-card{padding:21px}
  .article-list-card{padding:7px 18px}
  .contact-card{padding:25px}
  .faq-q-icon{display:none}
  .faq-a-inner{padding-left:19px}
  .article-body h1{font-size:32px}
  .spec-table{font-size:12px}
  .spec-table th,.spec-table td{padding:11px}
}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}