/* ==========================================================================
   QuickQ  —— 靛蓝 × 电光青「蓝图工程图」主题
   工程图纸纸感:图纸网格底、等宽标注、角标、虚线选路、路由拓扑
   ========================================================================== */

:root{
  --indigo:#4f46e5; --indigo-deep:#3730a3; --indigo-ink:#1e1b4b;
  --cyan:#0891b2; --cyan-bright:#22d3ee; --sky:#67e8f9; --sky-soft:#e0f7fe;
  --paper:#f4f6fb; --white:#ffffff; --ink:#1e1b4b; --muted:#5b6178;
  --line:#dde2f0; --soft:#eef0f8;
  --grad:linear-gradient(135deg,#22d3ee 0%,#4f46e5 62%,#3730a3 100%);
  --grad-soft:linear-gradient(135deg,#67e8f9 0%,#818cf8 100%);
  --mono:"Cascadia Code","Consolas","JetBrains Mono","SFMono-Regular",monospace;
  --shadow:0 1px 2px rgba(30,27,75,.05),0 10px 28px -14px rgba(30,27,75,.16);
  --shadow-lg:0 28px 64px -28px rgba(30,27,75,.34);
  --r:16px;
}

*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;
  color:var(--ink);background:var(--paper);line-height:1.7;font-size:16px}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
ul,ol{padding-left:1.3em}
.wrap{max-width:1180px;margin:0 auto;padding:0 24px}

/* ===== 蓝图标注条(topbar) ===== */
.topbar{background:var(--ink);color:var(--sky);font-family:var(--mono);font-size:12px;
  letter-spacing:.07em;border-bottom:1px solid rgba(103,232,249,.18)}
.topbar .wrap{display:flex;justify-content:space-between;align-items:center;gap:16px;height:38px}
.topbar a{color:var(--sky)}
.topbar a:hover{color:#fff}
.tb-left,.tb-right{display:flex;align-items:center;gap:14px;white-space:nowrap}
.tb-tag{color:var(--cyan-bright);font-weight:700}
.tb-live{display:inline-flex;align-items:center;gap:7px;color:#a7f3d0}
.tb-live .dot{width:7px;height:7px;border-radius:50%;background:#34d399;box-shadow:0 0 0 0 rgba(52,211,153,.6);animation:pulse 2s infinite}
@keyframes pulse{0%{box-shadow:0 0 0 0 rgba(52,211,153,.5)}70%{box-shadow:0 0 0 7px rgba(52,211,153,0)}100%{box-shadow:0 0 0 0 rgba(52,211,153,0)}}

/* ===== 导航 masthead ===== */
.masthead{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);
  backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}
.masthead .wrap{display:flex;align-items:center;gap:26px;height:66px}
.wordmark{display:flex;align-items:center;gap:11px;flex-shrink:0}
.wm-mark{width:36px;height:36px;border-radius:9px;box-shadow:var(--shadow)}
.wm-text{display:flex;flex-direction:column;line-height:1.15}
.wm-name{font-size:19px;font-weight:800;letter-spacing:.02em;background:var(--grad);
  -webkit-background-clip:text;background-clip:text;color:transparent}
.wm-sub{font-family:var(--mono);font-size:10px;letter-spacing:.12em;color:var(--muted);margin-top:2px}
.nav-wrap{display:flex;align-items:center;gap:4px;margin-left:auto}
.nav-wrap>a{position:relative;padding:8px 12px;font-size:15px;font-weight:500;color:var(--ink);border-radius:9px}
.nav-wrap>a:hover{background:var(--soft);color:var(--indigo)}
.nav-wrap>a.on{color:var(--indigo);font-weight:700}
.nav-wrap>a.on::after{content:"";position:absolute;left:12px;right:12px;bottom:4px;height:2px;
  background:var(--grad);border-radius:2px}
.dd{position:relative}
.dd>button{background:none;border:none;font:inherit;font-size:15px;font-weight:500;color:var(--ink);
  padding:8px 12px;border-radius:9px;cursor:pointer;font-family:inherit}
.dd>button:hover{background:var(--soft);color:var(--indigo)}
.dd-menu{position:absolute;top:calc(100% + 8px);left:0;min-width:200px;background:#fff;border:1px solid var(--line);
  border-radius:12px;box-shadow:var(--shadow-lg);padding:8px;display:none;flex-direction:column;z-index:60}
.dd:hover .dd-menu{display:flex}
.dd-menu a{padding:9px 12px;border-radius:8px;font-size:14px;color:var(--ink)}
.dd-menu a:hover{background:var(--soft);color:var(--indigo)}
.nav-search{width:40px;height:40px;border:1px solid var(--line);border-radius:10px;background:#fff;color:var(--indigo);
  font-size:17px;cursor:pointer;flex-shrink:0}
.nav-search:hover{border-color:var(--indigo);background:var(--sky-soft)}
.nav-cta{flex-shrink:0}
.nav-toggle{display:none;background:none;border:1px solid var(--line);border-radius:9px;width:42px;height:42px;
  font-size:22px;color:var(--ink);cursor:pointer;line-height:1}

/* ===== 按钮 ===== */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border-radius:11px;font-weight:600;
  padding:11px 20px;font-size:15px;border:1px solid transparent;cursor:pointer;transition:.18s}
.btn-primary{background:var(--grad);color:#fff;box-shadow:0 8px 22px -8px rgba(79,70,229,.55)}
.btn-primary:hover{transform:translateY(-1px);box-shadow:0 14px 30px -10px rgba(79,70,229,.65)}
.btn-ghost{background:#fff;color:var(--ink);border-color:var(--line);box-shadow:var(--shadow)}
.btn-ghost:hover{border-color:var(--indigo);color:var(--indigo)}
.btn-outline{background:transparent;color:var(--indigo);border-color:var(--indigo)}
.btn-outline:hover{background:var(--indigo);color:#fff}
.btn-lg{padding:14px 28px;font-size:16px;border-radius:13px}
.btn-sm{padding:9px 16px;font-size:14px}

/* ===== 蓝图 hero ===== */
.hero-print{position:relative;background:var(--paper);overflow:hidden;
  border-bottom:1px solid var(--line)}
.hero-print .bp-grid{position:absolute;inset:0;opacity:.9;
  background-image:linear-gradient(rgba(79,70,229,.055) 1px,transparent 1px),
    linear-gradient(90deg,rgba(79,70,229,.055) 1px,transparent 1px),
    linear-gradient(rgba(34,211,238,.04) 1px,transparent 1px),
    linear-gradient(90deg,rgba(34,211,238,.04) 1px,transparent 1px);
  background-size:132px 132px,132px 132px,26px 26px,26px 26px;
  -webkit-mask-image:linear-gradient(180deg,#000 0%,rgba(0,0,0,.25) 88%,transparent);
  mask-image:linear-gradient(180deg,#000 0%,rgba(0,0,0,.25) 88%,transparent)}
.hero-print .corner{position:absolute;width:26px;height:26px;border:2px solid var(--line);opacity:.9}
.hero-print .c1{top:18px;left:18px;border-right:0;border-bottom:0}
.hero-print .c2{top:18px;right:18px;border-left:0;border-bottom:0}
.hero-print .c3{bottom:18px;left:18px;border-right:0;border-top:0}
.hero-print .c4{bottom:18px;right:18px;border-left:0;border-top:0}
.hero-print .wrap{position:relative;z-index:2;padding:66px 24px 44px;text-align:center}
.hero-kicker{display:inline-flex;align-items:center;gap:9px;font-family:var(--mono);font-size:12.5px;
  letter-spacing:.14em;color:var(--indigo);background:#fff;border:1px solid var(--line);
  padding:6px 14px;border-radius:999px;box-shadow:var(--shadow)}
.hero-kicker .dot{width:8px;height:8px;border-radius:50%;background:var(--grad)}
.hero-title{font-size:clamp(34px,5.4vw,58px);font-weight:800;line-height:1.14;letter-spacing:-.02em;
  margin:22px 0 16px;color:var(--ink)}
.hero-title .hl{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero-sub{max-width:640px;margin:0 auto;color:var(--muted);font-size:17px}
.hero-cta{display:flex;justify-content:center;gap:14px;margin:28px 0 20px;flex-wrap:wrap}
.hero-trust{display:flex;justify-content:center;gap:22px;flex-wrap:wrap;font-size:13.5px;color:var(--muted)}
.trust-item{display:inline-flex;align-items:center;gap:7px;font-family:var(--mono);font-size:12px;letter-spacing:.05em}
.trust-item::before{content:"▸";color:var(--cyan)}
.blueprint-sheet{max-width:1040px;margin:46px auto 0;background:#fff;border:1px solid var(--line);
  border-radius:16px;box-shadow:var(--shadow-lg);padding:16px;position:relative}
.blueprint-sheet .sheet-note{position:absolute;top:10px;left:16px;right:16px;display:flex;
  justify-content:space-between;font-family:var(--mono);font-size:10.5px;letter-spacing:.1em;color:var(--muted)}
.blueprint-sheet svg{width:100%;height:auto;display:block}
.route,.compare,.nodes{width:100%;height:auto;display:block}

/* ===== 规格条 spec-strip ===== */
.spec-strip{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;background:#fff;
  border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);padding:22px 26px;
  position:relative;overflow:hidden}
.spec-strip::before{content:"";position:absolute;inset:0;
  background-image:linear-gradient(rgba(79,70,229,.03) 1px,transparent 1px),linear-gradient(90deg,rgba(79,70,229,.03) 1px,transparent 1px);
  background-size:22px 22px;pointer-events:none}
.spec-cell{position:relative;padding:6px 18px;border-left:1px solid var(--line)}
.spec-cell:first-child{border-left:0}
.spec-k{font-family:var(--mono);font-size:11px;letter-spacing:.12em;color:var(--cyan);text-transform:uppercase}
.spec-v{font-size:16px;font-weight:700;color:var(--ink);margin-top:5px}

/* ===== section / head / kicker ===== */
.section{padding:62px 0}
.section.alt{background:#fff;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.sec-head{text-align:center;max-width:680px;margin:0 auto 34px}
.sec-head.left{text-align:left;margin-left:0}
.sec-head h2{font-size:30px;font-weight:800;letter-spacing:-.01em;margin:8px 0 10px}
.sec-head p{color:var(--muted);font-size:16px}
.kicker{display:inline-block;font-family:var(--mono);font-size:11.5px;letter-spacing:.18em;
  color:var(--indigo);text-transform:uppercase;background:var(--sky-soft);padding:4px 11px;border-radius:7px}

/* ===== rel-grid / rel-card ===== */
.rel-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.rel-grid.single{grid-template-columns:repeat(4,1fr)}
.rel-card{display:block;background:#fff;border:1px solid var(--line);border-radius:14px;padding:22px;
  box-shadow:var(--shadow);transition:.18s;position:relative;overflow:hidden}
.rel-card::before{content:"";position:absolute;left:0;top:0;bottom:0;width:3px;background:var(--grad);
  opacity:0;transition:.18s}
.rel-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);border-color:var(--indigo)}
.rel-card:hover::before{opacity:1}
.rel-card .tag{display:inline-block;font-family:var(--mono);font-size:11px;letter-spacing:.08em;
  color:var(--cyan);background:var(--sky-soft);padding:3px 9px;border-radius:6px;margin-bottom:12px}
.rel-card h4{font-size:17px;font-weight:700;margin-bottom:7px;color:var(--ink)}
.rel-card p{font-size:14px;color:var(--muted)}

/* ===== bento ===== */
.bento{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.bento-card{background:#fff;border:1px solid var(--line);border-radius:14px;padding:24px;box-shadow:var(--shadow);
  transition:.18s;position:relative;overflow:hidden}
.bento-card::after{content:"";position:absolute;right:-28px;top:-28px;width:84px;height:84px;border-radius:50%;
  background:var(--sky-soft);opacity:.55}
.bento-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.bento-card .ic{font-size:30px;margin-bottom:14px;display:inline-block}
.bento-card h3{font-size:18px;font-weight:700;margin-bottom:8px}
.bento-card p{font-size:14.5px;color:var(--muted)}
.bento.glass{background:transparent}
.bento.glass .bento-card{background:rgba(255,255,255,.72);backdrop-filter:blur(8px)}

/* ===== 场景墙 sc-wall ===== */
.sc-wall{display:grid;grid-template-columns:repeat(4,1fr);gap:18px}
.sc-card{display:block;background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden;
  box-shadow:var(--shadow);transition:.18s}
.sc-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.sc-card img{aspect-ratio:16/10;object-fit:cover;width:100%}
.sc-cap{padding:14px 16px}
.sc-cap h4{font-size:16px;font-weight:700;margin-bottom:4px}
.sc-cap p{font-size:13px;color:var(--muted)}

/* ===== 步骤 steps ===== */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;max-width:940px;margin:0 auto}
.step{background:#fff;border:1px solid var(--line);border-radius:14px;padding:24px;box-shadow:var(--shadow);
  position:relative}
.step .n{width:40px;height:40px;border-radius:10px;background:var(--grad);color:#fff;font-weight:800;font-size:18px;
  display:flex;align-items:center;justify-content:center;margin-bottom:16px;font-family:var(--mono)}
.step h3{font-size:17px;font-weight:700;margin-bottom:8px}
.step p{font-size:14.5px;color:var(--muted)}
.step .b{line-height:1.6}

/* ===== 表格 ===== */
.table-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);background:#fff}
table{width:100%;border-collapse:collapse;font-size:14.5px;min-width:520px}
thead th{background:var(--ink);color:#fff;text-align:left;padding:13px 16px;font-weight:600;white-space:nowrap}
thead th:first-child{border-radius:13px 0 0 0}
thead th:last-child{border-radius:0 13px 0 0}
tbody td{padding:13px 16px;border-top:1px solid var(--line);color:var(--ink)}
tbody tr:nth-child(even){background:#fafbff}
tbody tr:hover{background:var(--sky-soft)}

/* ===== 提示 / 警示 / 引用 ===== */
.tip,.callout{border-radius:12px;padding:15px 18px;margin:20px 0;font-size:15px;position:relative;padding-left:48px}
.tip{background:var(--sky-soft);border:1px solid #bae6fd;color:#155e75}
.tip::before{content:"ⓘ";position:absolute;left:16px;top:14px;font-weight:700;color:var(--cyan);font-size:18px}
.callout{background:#fff7ed;border:1px solid #fed7aa;color:#9a3412}
.callout::before{content:"!";position:absolute;left:19px;top:13px;font-weight:800;color:#f97316;font-size:18px}
blockquote{border-left:3px solid var(--indigo);background:var(--soft);padding:14px 20px;border-radius:0 12px 12px 0;
  margin:20px 0;color:var(--indigo-ink);font-style:italic}

/* ===== FAQ ===== */
.faq-group{margin-bottom:18px}
.faq-group h2{font-size:20px;font-weight:700;margin-bottom:14px;color:var(--indigo-deep)}
.faq-group details{background:#fff;border:1px solid var(--line);border-radius:12px;margin-bottom:12px;
  box-shadow:var(--shadow);overflow:hidden}
.faq-group summary{cursor:pointer;padding:16px 20px;font-weight:600;font-size:15.5px;list-style:none;
  display:flex;justify-content:space-between;align-items:center}
.faq-group summary::-webkit-details-marker{display:none}
.faq-group summary::after{content:"＋";font-family:var(--mono);color:var(--indigo);font-weight:700;font-size:18px}
.faq-group details[open] summary::after{content:"－"}
.faq-a{padding:0 20px 18px;color:var(--muted);font-size:14.5px}

/* ===== CTA ===== */
.cta-band{background:var(--grad);border-radius:20px;padding:52px 40px;text-align:center;color:#fff;
  position:relative;overflow:hidden;box-shadow:var(--shadow-lg)}
.cta-band::before{content:"";position:absolute;inset:0;
  background-image:linear-gradient(rgba(255,255,255,.09) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.09) 1px,transparent 1px);
  background-size:30px 30px;opacity:.5}
.cta-band h2{font-size:30px;font-weight:800;margin-bottom:10px;position:relative}
.cta-band p{font-size:16px;opacity:.92;margin-bottom:24px;position:relative}
.cta-band .btn-ghost{position:relative;background:#fff;color:var(--indigo-deep);border:0;font-weight:700}

/* ===== 页脚 mastfoot ===== */
.mastfoot{background:var(--ink);color:#b9c2dd;border-top:3px solid var(--cyan);position:relative;overflow:hidden}
.mastfoot::before{content:"";position:absolute;inset:0;
  background-image:linear-gradient(rgba(103,232,249,.05) 1px,transparent 1px),linear-gradient(90deg,rgba(103,232,249,.05) 1px,transparent 1px);
  background-size:26px 26px;pointer-events:none}
.mastfoot .wrap{position:relative;padding:54px 24px 0}
.mf-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1fr;gap:34px;padding-bottom:38px}
.mf-brand p{font-size:14px;margin-top:14px;max-width:280px;line-height:1.8}
.mf-brand .wm-name{color:#fff;-webkit-text-fill-color:#fff;background:none}
.mf-brand .wm-sub{color:#8f9ac4}
.mf-brand .wm-mark{border:1px solid rgba(103,232,249,.35)}
.mf-col h4{color:#fff;font-size:13px;letter-spacing:.08em;text-transform:uppercase;margin-bottom:16px;
  font-family:var(--mono)}
.mf-col a{display:block;font-size:14px;padding:5px 0;color:#b9c2dd}
.mf-col a:hover{color:var(--sky)}
.foot-line{border-top:1px solid rgba(103,232,249,.14);padding:20px 0;text-align:center;
  font-family:var(--mono);font-size:12.5px;letter-spacing:.05em;color:#8f9ac4}

/* ===== 面包屑 ===== */
.breadcrumb{font-size:13.5px;color:var(--muted);margin-bottom:16px}
.breadcrumb a{color:var(--indigo)}
.breadcrumb a:hover{text-decoration:underline}
.breadcrumb .sep{margin:0 8px;color:#b8c0d8}

/* ===== page-hero(内页) ===== */
.page-hero{background:#fff;border-bottom:1px solid var(--line);padding:52px 0 46px;position:relative;overflow:hidden}
.page-hero::before{content:"";position:absolute;inset:0;
  background-image:linear-gradient(rgba(79,70,229,.045) 1px,transparent 1px),linear-gradient(90deg,rgba(79,70,229,.045) 1px,transparent 1px);
  background-size:26px 26px;-webkit-mask-image:linear-gradient(180deg,#000,transparent);
  mask-image:linear-gradient(180deg,#000,transparent)}
.page-hero .wrap{position:relative}
.page-hero h1{font-size:36px;font-weight:800;letter-spacing:-.01em;margin-bottom:12px}
.page-hero p{color:var(--muted);font-size:16.5px;max-width:720px}

/* ===== 左右图文 split ===== */
.split{display:grid;grid-template-columns:1fr 1fr;gap:40px;align-items:center}
.split.rev>div:first-child{order:2}
.split h2{font-size:26px;font-weight:800;margin-bottom:14px}
.split p{color:var(--muted);margin-bottom:14px}
.split ul{color:var(--muted);margin-bottom:16px}
.split ul li{margin-bottom:8px}
.split .img{border:1px solid var(--line);border-radius:16px;overflow:hidden;box-shadow:var(--shadow-lg)}
.split .img img{aspect-ratio:4/3;object-fit:cover;width:100%}

/* ===== 文章页 ===== */
.article-hero{background:#fff;border-bottom:1px solid var(--line);padding:44px 0 40px;position:relative;overflow:hidden}
.article-hero::before{content:"";position:absolute;inset:0;
  background-image:linear-gradient(rgba(79,70,229,.04) 1px,transparent 1px),linear-gradient(90deg,rgba(79,70,229,.04) 1px,transparent 1px);
  background-size:26px 26px;-webkit-mask-image:linear-gradient(180deg,#000,transparent);
  mask-image:linear-gradient(180deg,#000,transparent)}
.article-hero .wrap{position:relative}
.article-hero h1{font-size:34px;font-weight:800;letter-spacing:-.01em;margin-bottom:12px;line-height:1.3}
.article-hero p{color:var(--muted);max-width:720px}
.article-meta{display:flex;gap:20px;margin-top:16px;font-size:13px;color:var(--muted);font-family:var(--mono)}
.article-body{padding:44px 0 70px}
.article-layout{display:grid;grid-template-columns:240px 1fr;gap:44px;max-width:1080px;margin:0 auto;padding:0 24px}
.toc{position:sticky;top:90px;align-self:start;background:#fff;border:1px solid var(--line);
  border-radius:14px;padding:18px;box-shadow:var(--shadow)}
.toc h4{font-family:var(--mono);font-size:12px;letter-spacing:.12em;color:var(--cyan);
  text-transform:uppercase;margin-bottom:12px}
.toc a{display:block;font-size:14px;color:var(--muted);padding:6px 0;border-left:2px solid transparent;
  padding-left:12px}
.toc a:hover{color:var(--indigo);border-left-color:var(--indigo)}
.prose{font-size:16.5px;line-height:1.9;color:#2a2c40}
.prose h2{font-size:24px;font-weight:800;margin:36px 0 14px;padding-top:14px;color:var(--indigo-deep)}
.prose p{margin-bottom:16px}
.prose ul,.prose ol{margin-bottom:16px}
.prose li{margin-bottom:8px}
.prose figure{margin:26px 0}
.prose figure img{border-radius:14px;border:1px solid var(--line);box-shadow:var(--shadow)}
.prose figcaption{font-size:13px;color:var(--muted);text-align:center;margin-top:10px}

/* ===== 分享 ===== */
.share{display:flex;gap:10px;margin-top:36px;padding-top:22px;border-top:1px solid var(--line);flex-wrap:wrap}
.share a{font-size:13px;font-weight:600;color:var(--indigo);border:1px solid var(--line);border-radius:9px;
  padding:8px 14px;background:#fff;transition:.15s}
.share a:hover{border-color:var(--indigo);background:var(--sky-soft)}

/* ===== center-hero / search-box / sitemap ===== */
.center-hero{min-height:55vh;display:flex;align-items:center;justify-content:center;text-align:center;
  padding:60px 24px}
.center-hero h1{font-size:72px;font-weight:800;background:var(--grad);-webkit-background-clip:text;
  background-clip:text;color:transparent;line-height:1}
.center-hero p{color:var(--muted);margin:18px 0 26px}
.search-box{display:flex;gap:10px;max-width:520px;margin:0 auto}
.search-box input{flex:1;padding:12px 16px;border:1px solid var(--line);border-radius:11px;font-size:15px;font-family:inherit}
.search-box input:focus{outline:none;border-color:var(--indigo);box-shadow:0 0 0 3px var(--sky-soft)}
.sitemap-list h2{font-size:20px;font-weight:700;margin:30px 0 12px;color:var(--indigo-deep);
  border-bottom:2px solid var(--line);padding-bottom:8px}
.sitemap-list>div{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.sitemap-list a{font-size:14px;color:var(--indigo);padding:4px 0;display:block}
.sitemap-list a:hover{text-decoration:underline}

/* ===== 返回顶部 ===== */
.backtop{position:fixed;right:22px;bottom:24px;width:46px;height:46px;border-radius:12px;background:var(--grad);
  color:#fff;font-size:20px;border:0;cursor:pointer;box-shadow:var(--shadow-lg);opacity:0;visibility:hidden;
  transform:translateY(10px);transition:.25s;z-index:90}
.backtop.show{opacity:1;visibility:visible;transform:translateY(0)}
.backtop:hover{transform:translateY(-2px)}

/* ===== 滚动渐显 ===== */
.reveal{opacity:0;transform:translateY(22px);transition:opacity .6s ease,transform .6s ease}
.reveal.in{opacity:1;transform:none}

/* ===== 响应式 ===== */
@media (max-width:980px){
  .spec-strip{grid-template-columns:repeat(2,1fr);gap:0}
  .spec-cell:nth-child(3){border-left:0}
  .spec-cell{padding:14px 18px}
  .rel-grid,.bento{grid-template-columns:repeat(2,1fr)}
  .rel-grid.single,.sc-wall{grid-template-columns:repeat(2,1fr)}
  .steps{grid-template-columns:1fr;max-width:460px}
  .mf-grid{grid-template-columns:1fr 1fr}
  .split{grid-template-columns:1fr;gap:28px}
  .split.rev>div:first-child{order:0}
  .article-layout{grid-template-columns:1fr}
  .toc{position:static;display:none}
  .sitemap-list>div{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:680px){
  .nav-wrap>a,.dd,.nav-cta{display:none}
  .nav-wrap.open>a,.nav-wrap.open .dd,.nav-wrap.open .nav-cta{display:flex}
  .nav-wrap.open{flex-direction:column;align-items:flex-start;position:absolute;top:66px;left:0;right:0;
    background:#fff;border-bottom:1px solid var(--line);padding:14px 24px;gap:6px;box-shadow:var(--shadow-lg)}
  .nav-wrap.open .dd-menu{position:static;display:flex;box-shadow:none;border:0;padding:0 0 0 12px}
  .nav-toggle{display:block}
  .topbar .tb-right{display:none}
  .rel-grid,.bento,.rel-grid.single,.sc-wall{grid-template-columns:1fr}
  .mf-grid{grid-template-columns:1fr}
  .sitemap-list>div{grid-template-columns:1fr}
  .hero-cta .btn{width:100%}
  .cta-band{padding:38px 22px}
  .cta-band h2{font-size:24px}
}