:root{
  --brand:#3b7dff;--brand-dark:#2563eb;--brand-light:#eff4ff;
  --green:#10b981;--amber:#f59e0b;--red:#ef4444;
  --bg:#f4f6fb;--surface:#fff;--border:#e4e8f5;
  --text:#1a1d2e;--muted:#6b7280;--light:#9ca3af;
  --radius:14px;--shadow:0 2px 16px rgba(59,125,255,.08);
}
*{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;}
body{font-family:'Noto Sans SC','PingFang SC','Microsoft YaHei',sans-serif;background:var(--bg);color:var(--text);font-size:15px;line-height:1.7;}

/* NAV */
nav{background:var(--surface);border-bottom:1px solid var(--border);padding:0 1.5rem;display:flex;align-items:center;justify-content:space-between;height:58px;position:sticky;top:0;z-index:100;box-shadow:0 1px 10px rgba(59,125,255,.07);}
.nav-logo{display:flex;align-items:center;gap:9px;text-decoration:none;}
.nav-icon{width:32px;height:32px;background:linear-gradient(135deg,var(--brand),#06b6d4);border-radius:9px;display:flex;align-items:center;justify-content:center;font-size:17px;}
.nav-name{font-size:16px;font-weight:700;color:var(--text);}
.nav-right{display:flex;align-items:center;gap:12px;}
.nav-link{font-size:13px;color:var(--muted);text-decoration:none;}
.nav-link:hover{color:var(--brand);}
.nav-btn{background:var(--brand);color:#fff;border:none;border-radius:8px;padding:7px 16px;font-size:13px;cursor:pointer;text-decoration:none;font-weight:500;}
.nav-btn:hover{background:var(--brand-dark);}
.nav-menu-btn{display:flex;align-items:center;gap:5px;background:var(--brand-light);color:var(--brand);border:1px solid rgba(59,125,255,.2);border-radius:8px;padding:7px 14px;font-size:13px;cursor:pointer;font-weight:500;font-family:inherit;}
.nav-menu-btn:hover{background:#e2ebff;}

/* MEGA MENU OVERLAY */
.menu-mask{position:fixed;inset:0;background:rgba(20,26,46,.45);z-index:199;opacity:0;pointer-events:none;transition:opacity .2s;}
.menu-mask.open{opacity:1;pointer-events:auto;}
.mega-menu{position:fixed;top:0;right:0;height:100%;width:min(340px,86vw);background:var(--surface);z-index:200;box-shadow:-8px 0 30px rgba(20,26,46,.15);transform:translateX(100%);transition:transform .25s ease;overflow-y:auto;}
.mega-menu.open{transform:translateX(0);}
.mm-head{display:flex;align-items:center;justify-content:space-between;padding:1.1rem 1.3rem;border-bottom:1px solid var(--border);position:sticky;top:0;background:var(--surface);}
.mm-title{font-size:15px;font-weight:700;}
.mm-close{width:30px;height:30px;border-radius:50%;border:none;background:var(--bg);color:var(--muted);font-size:16px;cursor:pointer;display:flex;align-items:center;justify-content:center;}
.mm-close:hover{background:var(--border);}
.mm-group{padding:1rem 1.3rem 0.2rem;}
.mm-group-title{font-size:11px;font-weight:700;color:var(--light);text-transform:uppercase;letter-spacing:.06em;margin-bottom:.5rem;}
.mm-item{display:flex;align-items:center;gap:10px;padding:.65rem .5rem;border-radius:9px;text-decoration:none;color:var(--text);font-size:14px;}
.mm-item:hover{background:var(--brand-light);color:var(--brand);}
.mm-item.current{background:var(--brand-light);color:var(--brand);font-weight:700;}
.mm-emoji{font-size:16px;width:22px;text-align:center;flex-shrink:0;}
.mm-foot{padding:1.2rem 1.3rem 1.8rem;}

/* HERO */
.hero{background:linear-gradient(135deg,#e8efff 0%,#dff5f7 100%);padding:3.5rem 1.5rem 2.5rem;text-align:center;position:relative;overflow:hidden;}
.hero::before{content:'';position:absolute;inset:0;background:radial-gradient(ellipse 55% 55% at 75% 25%,rgba(59,125,255,.13) 0%,transparent 70%),radial-gradient(ellipse 40% 40% at 20% 80%,rgba(6,182,212,.10) 0%,transparent 70%);}
.hero-tag{display:inline-flex;align-items:center;gap:6px;background:rgba(59,125,255,.12);color:var(--brand);border:1px solid rgba(59,125,255,.2);border-radius:20px;padding:4px 14px;font-size:13px;font-weight:500;margin-bottom:1rem;position:relative;}
.hero h1{font-size:clamp(24px,5vw,38px);font-weight:700;color:var(--text);margin-bottom:.7rem;position:relative;}
.hero h1 span{color:var(--brand);}
.hero p{font-size:14px;color:var(--muted);max-width:500px;margin:0 auto 1.8rem;position:relative;}
.hero-btns{display:flex;gap:10px;justify-content:center;flex-wrap:wrap;position:relative;}
.btn-p{background:var(--brand);color:#fff;border:none;border-radius:10px;padding:11px 24px;font-size:14px;font-weight:500;cursor:pointer;text-decoration:none;display:inline-flex;align-items:center;gap:7px;box-shadow:0 4px 14px rgba(59,125,255,.35);}
.btn-p:hover{background:var(--brand-dark);}
.btn-s{background:var(--surface);color:var(--brand);border:1.5px solid var(--brand);border-radius:10px;padding:11px 24px;font-size:14px;font-weight:500;cursor:pointer;text-decoration:none;display:inline-flex;align-items:center;gap:7px;}
.btn-s:hover{background:var(--brand-light);}

/* STEPS NAV */
.steps-nav{background:var(--surface);border-bottom:1px solid var(--border);display:flex;overflow-x:auto;justify-content:center;}
.sn-item{display:flex;align-items:center;gap:7px;padding:13px 18px;font-size:13px;color:var(--light);white-space:nowrap;cursor:pointer;border-bottom:2px solid transparent;text-decoration:none;transition:all .2s;}
.sn-item:hover{color:var(--brand);}
.sn-item.active{color:var(--brand);border-bottom-color:var(--brand);font-weight:500;}
.sn-dot{width:20px;height:20px;border-radius:50%;background:#e5e7eb;display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:700;color:#9ca3af;flex-shrink:0;}
.sn-item.active .sn-dot{background:var(--brand);color:#fff;}

/* MAIN */
main{max-width:860px;margin:0 auto;padding:2.5rem 1.5rem 5rem;}

/* SECTION */
.sec{margin-bottom:3.5rem;}
.sec-hd{display:flex;align-items:center;gap:12px;margin-bottom:1.4rem;padding-bottom:.9rem;border-bottom:1px solid var(--border);}
.sec-num{width:34px;height:34px;background:var(--brand);color:#fff;border-radius:9px;display:flex;align-items:center;justify-content:center;font-size:15px;font-weight:700;flex-shrink:0;}
.sec-title{font-size:19px;font-weight:700;color:var(--text);}
.sec-sub{font-size:12px;color:var(--muted);margin-top:2px;}

/* STEP CARD */
.sc{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow);margin-bottom:1rem;}
.sc-top{display:flex;align-items:flex-start;gap:13px;padding:1.2rem 1.4rem;}
.sc-icon{width:40px;height:40px;border-radius:11px;display:flex;align-items:center;justify-content:center;font-size:19px;flex-shrink:0;}
.ic-blue{background:#eff4ff;} .ic-cyan{background:#e0f7fa;} .ic-green{background:#d1fae5;} .ic-amber{background:#fef3c7;}
.sc-body{flex:1;}
.sc-label{font-size:11px;font-weight:700;color:var(--brand);text-transform:uppercase;letter-spacing:.06em;margin-bottom:3px;}
.sc-name{font-size:15px;font-weight:700;color:var(--text);margin-bottom:4px;}
.sc-desc{font-size:13px;color:var(--muted);line-height:1.65;}
.sc-desc a{color:var(--brand);}

/* IMAGE AREA */
.img-area{border-top:1px solid var(--border);background:#f8faff;padding:1.2rem 1.4rem;}
.img-grid{display:grid;gap:10px;}
.img-grid.cols-2{grid-template-columns:1fr 1fr;}
.img-grid.cols-1{grid-template-columns:1fr;}
.img-wrap{border-radius:10px;overflow:hidden;border:1px solid var(--border);background:#fff;}
.img-wrap img{width:100%;height:auto;display:block;}
.img-caption{font-size:11px;color:var(--muted);text-align:center;padding:6px 8px;background:#fff;border-top:1px solid var(--border);}
.img-placeholder{aspect-ratio:16/10;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:6px;background:repeating-linear-gradient(135deg,#f2f5fc,#f2f5fc 10px,#eaeffb 10px,#eaeffb 20px);color:var(--light);}
.img-placeholder .ph-icon{font-size:26px;opacity:.6;}
.img-placeholder .ph-text{font-size:11px;color:var(--muted);text-align:center;padding:0 .8rem;max-width:220px;}
.img-placeholder[data-src]{background:none;}

/* INFO BOXES */
.ib{border-radius:10px;padding:11px 14px;margin:1rem 0;display:flex;gap:9px;align-items:flex-start;font-size:13px;line-height:1.6;}
.ib.tip{background:#d1fae5;color:#065f46;border:1px solid #a7f3d0;}
.ib.warn{background:#fef3c7;color:#92400e;border:1px solid #fde68a;}
.ib.note{background:#eff4ff;color:#1e40af;border:1px solid #c7d2fe;}
.ib.red{background:#fee2e2;color:#991b1b;border:1px solid #fca5a5;}
.ib-icon{font-size:15px;flex-shrink:0;margin-top:1px;}
.ib a{color:inherit;font-weight:700;text-decoration:underline;}

/* FAQ */
.faq-list{display:flex;flex-direction:column;gap:10px;}
.faq-item{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:1rem 1.25rem;box-shadow:var(--shadow);}
.faq-q{font-size:14px;font-weight:700;color:var(--text);margin-bottom:6px;display:flex;gap:8px;}
.faq-q::before{content:'Q';color:var(--brand);font-weight:800;flex-shrink:0;}
.faq-a{font-size:13px;color:var(--muted);line-height:1.7;padding-left:18px;}
.faq-a::before{content:'A：';color:var(--green);font-weight:700;}

/* HUB LIST (directory-style pages) */
.hub-list{display:flex;flex-direction:column;gap:12px;}
.hub-item{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:1.1rem 1.3rem;display:flex;align-items:center;gap:14px;text-decoration:none;color:var(--text);}
.hub-item:hover{border-color:var(--brand);}
.hub-icon{width:44px;height:44px;border-radius:12px;background:var(--brand-light);display:flex;align-items:center;justify-content:center;font-size:20px;flex-shrink:0;}
.hub-body{flex:1;}
.hub-name{font-size:15px;font-weight:700;margin-bottom:2px;}
.hub-desc{font-size:12.5px;color:var(--muted);}
.hub-arrow{color:var(--light);font-size:18px;flex-shrink:0;}

/* CTA */
.cta{background:linear-gradient(135deg,#eff4ff,#dff5f7);border-radius:var(--radius);padding:2rem;text-align:center;border:1px solid var(--border);}

/* RELATED LINKS */
.related{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px;margin-top:1rem;}
.related a{background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:.8rem 1rem;text-decoration:none;color:var(--text);font-size:13px;font-weight:500;display:flex;align-items:center;gap:6px;}
.related a:hover{border-color:var(--brand);color:var(--brand);}

/* FOOTER */
footer{background:var(--surface);border-top:1px solid var(--border);text-align:center;padding:1.8rem 1.5rem;color:var(--muted);font-size:13px;}
footer a{color:var(--brand);text-decoration:none;}

/* ANIMATIONS */
@keyframes fadeUp{from{opacity:0;transform:translateY(18px);}to{opacity:1;transform:none;}}
.sec{animation:fadeUp .5s ease both;}
.sec:nth-child(1){animation-delay:.05s;} .sec:nth-child(2){animation-delay:.11s;}
.sec:nth-child(3){animation-delay:.17s;} .sec:nth-child(4){animation-delay:.23s;}
.sec:nth-child(5){animation-delay:.29s;}

@media(max-width:640px){
  .img-grid.cols-2{grid-template-columns:1fr;}
  main{padding:1.8rem 1rem 4rem;}
  .hero{padding:2.5rem 1rem 2rem;}
  .nav-link{display:none;}
}