/* ================================================================
   建圈强链官网 · v2 视觉层（仅首页 index.html 引用）
   2026-10-18 · 与 _样张/sample.css 同一套令牌
   作用域：导航 / 首屏 / 资质条 / 架构卡 / 场景卡 / CTA / 页脚
   ================================================================ */
:root{
  --v2-navy:#1F3864; --v2-ink:#111A28; --v2-ink2:#5A6678; --v2-ink3:#8A94A4;
  --v2-gold:#C9A063; --v2-gold-soft:#E3CB9B; --v2-gold-deep:#8E6B39;
  --v2-line:#E6EBF2; --v2-bg:#F7F9FC; --v2-r:14px;
  --v2-shadow:0 1px 2px rgba(16,32,64,.04),0 18px 40px -28px rgba(16,32,64,.35);
}

/* ---------- 导航：当前页态 ---------- */
.nav-links a.on{background:rgba(201,160,99,.2);color:#fff;border-color:rgba(201,160,99,.55)}
.nav-links a.on:hover{background:rgba(201,160,99,.26)}
.brand img{filter:none}

/* ---------- 首屏 ---------- */
.hero{background:radial-gradient(120% 90% at 80% 14%,rgba(201,160,99,.13),transparent 56%),linear-gradient(160deg,#0B1526,#14263F 62%,#16304F);}
.hero::after{background:radial-gradient(circle,rgba(201,160,99,.10),transparent 66%)}
.hero .wrap{grid-template-columns:minmax(0,1fr) 500px;gap:56px;padding-top:84px;padding-bottom:72px;align-items:center}
.hero h1{font-size:56px;line-height:1.14;letter-spacing:-.015em;margin:26px 0 0}
.hero h1 .hl{background:linear-gradient(100deg,#E6CFA0,#C9A063);-webkit-background-clip:text;background-clip:text;color:transparent;text-shadow:none}
.hero .sub{margin-top:30px;font-size:16.5px;line-height:1.85;color:rgba(255,255,255,.66);max-width:560px}
.hero-btns{margin-top:40px;gap:14px}
.btn{height:52px;padding:0 30px;border-radius:999px;font-size:15px;display:inline-flex;align-items:center;justify-content:center}
.btn-gold{background:linear-gradient(120deg,#CBA367,#DEC294);color:#101B2C;box-shadow:0 10px 24px -12px rgba(201,160,99,.5)}
.btn-gold:hover{transform:translateY(-1px);box-shadow:0 16px 30px -14px rgba(201,160,99,.55)}
.btn-ghost{background:transparent;border:1px solid rgba(255,255,255,.24);color:rgba(255,255,255,.9)}
.btn-ghost:hover{border-color:rgba(201,160,99,.7);color:var(--v2-gold-soft);background:transparent}

/* 首屏右：几何闭环图 */
.figure{position:relative}
.fig-cap{display:flex;align-items:center;gap:12px;margin-bottom:24px;font-size:11.5px;letter-spacing:.2em;color:rgba(255,255,255,.44)}
.fig-cap::before{content:'';width:22px;height:1px;background:rgba(201,160,99,.6)}
.fig-cap b{color:var(--v2-gold-soft);font-weight:400}
.loop{position:relative;width:100%;max-width:500px;aspect-ratio:520/420}
.loop svg{position:absolute;inset:0;width:100%;height:100%}
.loop-node{position:absolute;display:flex;flex-direction:column;align-items:center;gap:6px;transform:translate(-50%,-50%)}
.loop-node .lb{font-size:14px;font-weight:700;color:#fff;white-space:nowrap}
.loop-node .en{font-size:9.5px;letter-spacing:.16em;color:rgba(255,255,255,.4);white-space:nowrap}
.loop-core{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);width:138px;height:138px;border-radius:50%;
  border:1px solid rgba(201,160,99,.3);background:radial-gradient(circle at 50% 45%,rgba(201,160,99,.16),rgba(201,160,99,.02) 72%);
  display:grid;place-items:center;box-shadow:0 0 60px -10px rgba(201,160,99,.35)}
.loop-core img{width:128px;height:128px;object-fit:cover;border-radius:50%;mix-blend-mode:screen;
  filter:saturate(1.05) brightness(1.16) contrast(1.05);
  -webkit-mask-image:radial-gradient(circle,#000 74%,rgba(0,0,0,0) 94%);mask-image:radial-gradient(circle,#000 74%,rgba(0,0,0,0) 94%)}

/* ---------- 资质条 ---------- */
.datastrip{background:linear-gradient(180deg,#0E1E36,#12243F);border-top:1px solid rgba(201,160,99,.16);border-bottom:1px solid rgba(201,160,99,.14)}
.datastrip .wrap{display:block;padding:0 24px}
.datastrip .stat:nth-child(3){padding-right:0}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:0;padding:6px 0 2px}
.stat{display:flex;flex-direction:column;gap:0;padding:20px 24px;background:transparent;border:0;border-radius:0;
  border-left:1px solid rgba(255,255,255,.08);border-top:1px solid rgba(255,255,255,.08)}
.stat:nth-child(-n+3){border-top:0;padding-top:14px}
.stat:nth-child(3n+1){border-left:0;padding-left:0}
.stat:first-child{border-left:0;padding-left:0}
.stat .ic{display:none}
.stat .num{font-size:30px;font-weight:700;color:#fff;line-height:1.05;white-space:nowrap;letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.stat .num small{font-size:15px;font-weight:700;color:rgba(255,255,255,.62);margin-left:2px}
.stat .lb{font-size:12.5px;color:rgba(255,255,255,.55);margin-top:8px;white-space:normal;line-height:1.45}
.badges{display:flex;gap:0;border-top:1px solid rgba(255,255,255,.08);padding:18px 0 6px}
.badge-item{display:flex;align-items:baseline;gap:12px;padding-right:40px;margin-right:40px;border-right:1px solid rgba(255,255,255,.08)}
.badge-item:last-child{border-right:0;margin-right:0;padding-right:0}
.badge-item .bi-t{font-size:15px;font-weight:700;color:var(--v2-gold-soft);letter-spacing:.01em}
.badge-item .bi-k{font-size:12.5px;color:rgba(255,255,255,.55)}

/* ---------- 区块标题 ---------- */
.section.light{background:var(--v2-bg)}
.section.white{background:#fff}
.sec-head{align-items:flex-end;margin-bottom:38px}
.sec-head h2{font-size:36px;line-height:1.3;letter-spacing:-.01em;color:var(--v2-navy);margin:14px 0 0}
.sec-head p{margin-top:12px;font-size:15px;color:var(--v2-ink2);line-height:1.75}
.eyebrow{font-size:12px;letter-spacing:.18em;color:var(--v2-gold-deep);font-weight:700}
.link-more.right{font-size:13.5px;color:var(--v2-ink3);font-weight:700;letter-spacing:.02em}
.link-more.right:hover{color:var(--v2-navy)}

/* ---------- 三层架构 ---------- */
.layers-wrap{position:relative}
.layers{display:grid;grid-template-columns:1fr 26px 1fr 26px 1fr;gap:0;align-items:stretch}
.arrow-cell{display:grid;place-items:center}
.flow-arrow{width:24px;height:24px;display:grid;place-items:center;border-radius:50%;background:#fff;
  border:1px solid rgba(201,160,99,.45);color:var(--v2-gold);box-shadow:0 6px 14px -8px rgba(16,32,64,.35)}
.flow-arrow svg{width:12px;height:12px}
.layer{display:flex;flex-direction:column;background:#fff;border:1px solid var(--v2-line);border-radius:var(--v2-r);
  padding:32px 28px 26px;box-shadow:var(--v2-shadow);overflow:visible;
  transition:transform .22s,box-shadow .22s,border-color .22s}
.layer:hover{transform:translateY(-3px);border-color:#D9E2EF;box-shadow:0 1px 2px rgba(16,32,64,.05),0 26px 50px -30px rgba(16,32,64,.45)}
.layer::before{display:none}
.layer .no{font-size:26px;font-weight:700;line-height:1;color:#D8E1EF;letter-spacing:0;font-variant-numeric:tabular-nums;display:block}
.layer .no::after{display:none}
.layer h3{font-size:21px;font-weight:700;color:var(--v2-navy);margin:16px 0 0;letter-spacing:-.01em}
.layer .role{font-size:13px;color:var(--v2-ink3);font-weight:400;letter-spacing:0;margin-top:8px}
.layer .desc{font-size:14.5px;line-height:1.85;color:var(--v2-ink2);margin-top:16px}
.layer .tags{margin-top:auto;padding-top:24px;gap:8px}
.layer .tags span{font-size:12.5px;color:var(--v2-ink2);background:#fff;border:1px solid var(--v2-line);border-radius:999px;padding:6px 13px;line-height:1}
.layer .tags span:hover{border-color:rgba(201,160,99,.6);color:var(--v2-navy)}
.loop-rail{position:relative;height:58px;margin-top:20px}
.loop-rail::before{content:'';position:absolute;left:16.666%;right:16.666%;top:0;bottom:16px;
  border:1px dashed rgba(201,160,99,.62);border-top:0;border-radius:0 0 14px 14px}
.loop-rail::after{content:'';position:absolute;left:16.666%;top:-2px;transform:translate(-50%,0);
  border-left:5px solid transparent;border-right:5px solid transparent;border-bottom:8px solid rgba(201,160,99,.85)}
.loop-rail-cap{text-align:center;font-size:11.5px;letter-spacing:.1em;color:var(--v2-ink3);margin-top:4px}

/* ---------- 场景卡 ---------- */
.cases{display:grid;grid-template-columns:repeat(3,1fr);gap:26px;align-items:stretch}
.case{display:flex;flex-direction:column;background:#fff;border:1px solid var(--v2-line);border-radius:var(--v2-r);
  padding:0;box-shadow:var(--v2-shadow);overflow:hidden;transition:transform .22s,box-shadow .22s,border-color .22s}
.case:hover{transform:translateY(-3px);border-color:#D9E2EF;box-shadow:0 1px 2px rgba(16,32,64,.05),0 26px 50px -30px rgba(16,32,64,.45)}
.case .illus{position:relative;aspect-ratio:1280/658;background:linear-gradient(180deg,#F4F7FB,#EDF1F7);overflow:hidden;margin:0}
.case .illus .art{width:100%;height:100%;object-fit:cover;filter:saturate(.92) contrast(1.03)}
.case .ph{display:none}
.case h4{font-size:20px;font-weight:700;color:var(--v2-navy);margin:24px 26px 0;letter-spacing:-.01em}
.case .sub2{font-size:13px;color:var(--v2-gold-deep);margin:7px 26px 0;letter-spacing:.02em}
.case .metrics{margin-top:auto;padding:20px 26px 26px;border-top:1px solid var(--v2-line);display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.case .metrics .m{text-align:left}
.case .metrics .v{font-size:21px;font-weight:700;color:var(--v2-navy);font-variant-numeric:tabular-nums;letter-spacing:-.02em}
.case .metrics .v em{font-style:normal;color:var(--v2-navy)}
.case .metrics .k{margin-top:5px;font-size:12px;color:var(--v2-ink3)}

/* ---------- CTA ---------- */
.cta{background:linear-gradient(170deg,#0B1526,#14263F 70%,#16304F);padding:0}
.cta .wrap{padding:88px 24px 76px;text-align:center}
.cta h2{font-size:44px;letter-spacing:-.01em}
.cta h2 .hl{color:var(--v2-gold-soft);text-shadow:none}
.cta .sub{font-size:16px;color:rgba(255,255,255,.66);line-height:1.8;margin-top:18px}
.cta .btn{margin-top:34px}
.cta .contact{margin-top:34px;font-size:13.5px;color:rgba(255,255,255,.5);align-items:center}
.cta .contact .sep{opacity:.3;margin:0 4px}
.cta .contact a{color:rgba(255,255,255,.78)}

/* ---------- 页脚 ---------- */
footer{background:#0A1220;padding:34px 0 30px}
footer .wrap{display:flex;flex-direction:column;align-items:flex-start;gap:16px;padding:0 24px}
.f-brand{display:flex;align-items:center;justify-content:flex-start;gap:14px}
.f-brand img{height:40px;width:auto}
.f-brand span{font-size:14px;font-weight:700;color:#fff}
.f-bottom{display:flex;flex-wrap:wrap;justify-content:flex-start;gap:10px 26px;width:100%;font-size:12px;color:rgba(255,255,255,.42);border-top:1px solid rgba(255,255,255,.08);padding-top:16px}

/* ---------- 响应式 ---------- */
@media (max-width:1200px){
  .hero .wrap{grid-template-columns:1fr;gap:44px}
  .figure{margin-top:8px}
  .loop{max-width:440px}
  .stats{grid-template-columns:repeat(3,1fr)}
  .stat:nth-child(4){border-left:0;padding-left:0}
  .layers{grid-template-columns:1fr}
  .arrow-cell{padding:14px 0;transform:rotate(90deg)}
  .loop-rail{display:none}
  .cases{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:760px){
  /* 导航压成两行：logo + 按钮一行，链接横向滚动一行 */
  .nav .wrap{height:auto;flex-wrap:wrap;align-items:center;gap:8px 10px;padding:10px 14px}
  .brand{order:1}
  .brand img{height:42px}
  .nav-cta{order:2;margin-left:auto;height:38px;padding:0 18px;font-size:13px}
  .nav-links{order:3;width:100%;flex-wrap:nowrap;overflow-x:auto;justify-content:flex-start;gap:4px;margin:4px 0 0;padding-bottom:2px}
  .nav-links::-webkit-scrollbar{display:none}
  .nav-links a{padding:7px 11px;font-size:13px}

  .hero .wrap{padding-top:52px;padding-bottom:48px}
  .hero h1{font-size:30px}
  .hero .sub{font-size:15px}
  .btn{height:46px;padding:0 22px;font-size:14px}
  .loop-core{width:104px;height:104px}
  .loop-core img{width:96px;height:96px}
  .loop-node .lb{font-size:12px}
  .loop-node .en{font-size:8.5px}
  .stats{grid-template-columns:repeat(2,1fr)}
  .stat:nth-child(odd){border-left:0;padding-left:0}
  .badges{flex-direction:column;gap:10px}
  .badge-item{border-right:0;padding-right:0;margin-right:0}
  .sec-head h2{font-size:24px}
  .cases{grid-template-columns:1fr}
  .cta h2{font-size:26px}
  .f-brand span{font-size:13px}
}