/* ==========================================================================
   BT 钱包 · 官网样式
   设计语言：苹果风 —— 大量留白、克制配色、强字体层级、滚动渐显。
   色值集中在 :root，不散落 hex；品牌蓝与钱包保持一致（#2980FE / #3D8BFF）。
   ========================================================================== */
:root{
  --ink:#1d1d1f;
  --ink-2:#6e6e73;
  --ink-3:#86868b;
  --bg:#ffffff;
  --soft:#f5f5f7;
  --soft-2:#ebebeb;
  --line:#d2d2d7;
  --brand:#2980FE;
  --brand-2:#3D8BFF;
  --brand-deep:#0a58d6;
  --gold:#f0b90b;            /* 仅在强调处点缀，不喧宾夺主 */
  --radius:18px;
  --radius-lg:28px;
  --maxw:1120px;
  --shadow-sm:0 1px 2px rgba(0,0,0,.06), 0 4px 16px rgba(0,0,0,.05);
  --shadow-md:0 10px 40px rgba(0,0,0,.10);
  --ease:cubic-bezier(.22,.61,.36,1);
  --font:-apple-system,BlinkMacSystemFont,"SF Pro Display","Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",Roboto,Helvetica,Arial,sans-serif;
}

*{box-sizing:border-box;}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%;}
body{
  margin:0;background:var(--bg);color:var(--ink);
  font-family:var(--font);font-size:17px;line-height:1.6;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
img{max-width:100%;display:block;}
a{color:var(--brand-deep);text-decoration:none;}
a:hover{text-decoration:underline;}
h1,h2,h3{margin:0;letter-spacing:-.02em;font-weight:700;}
p{margin:0;}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px;}

/* ---------- 顶部导航 ---------- */
.nav{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.72);
  backdrop-filter:saturate(180%) blur(20px);
  -webkit-backdrop-filter:saturate(180%) blur(20px);
  border-bottom:1px solid rgba(0,0,0,.06);
}
.nav-inner{display:flex;align-items:center;justify-content:space-between;height:56px;}
.nav-logo{display:flex;align-items:center;gap:10px;}
.nav-logo img{height:26px;width:auto;}
.nav-links{display:flex;align-items:center;gap:30px;}
.nav-links a{color:var(--ink);font-size:14px;font-weight:500;}
.nav-links a:hover{color:var(--brand-deep);text-decoration:none;}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  border:0;border-radius:980px;font-weight:600;cursor:pointer;
  padding:11px 22px;font-size:15px;transition:transform .2s var(--ease),background .2s,box-shadow .2s;
  text-decoration:none;white-space:nowrap;
}
.btn:hover{text-decoration:none;transform:translateY(-1px);}
.btn:active{transform:translateY(0);}
.btn-primary{background:var(--brand);color:#fff;box-shadow:0 6px 18px rgba(41,128,254,.30);}
.btn-primary:hover{background:var(--brand-deep);}
.btn-dark{background:var(--ink);color:#fff;}
.btn-dark:hover{background:#000;}
.btn-ghost{background:rgba(0,0,0,.05);color:var(--ink);}
.btn-ghost:hover{background:rgba(0,0,0,.09);}
.btn-lg{padding:14px 30px;font-size:17px;}
.nav-toggle{display:none;background:none;border:0;cursor:pointer;padding:8px;}
.nav-toggle span{display:block;width:22px;height:2px;background:var(--ink);margin:4px 0;border-radius:2px;}

/* ---------- Hero ---------- */
.hero{text-align:center;padding:84px 24px 40px;}
.hero .eyebrow{
  color:var(--brand-deep);font-weight:600;font-size:15px;letter-spacing:.01em;margin-bottom:18px;
}
.hero h1{
  font-size:clamp(40px,6vw,72px);line-height:1.05;margin:0 auto 22px;max-width:14ch;
}
.hero .sub{
  font-size:clamp(18px,2.4vw,22px);color:var(--ink-2);max-width:34ch;margin:0 auto 34px;line-height:1.5;
}
.hero-cta{display:flex;gap:14px;justify-content:center;flex-wrap:wrap;margin-bottom:14px;}
.hero-note{font-size:13px;color:var(--ink-3);}
.hero-art{margin:54px auto 0;max-width:1100px;}
.hero-art img{width:100%;height:auto;border-radius:var(--radius-lg);box-shadow:var(--shadow-md);}

/* ---------- 信任条 ---------- */
.trust{background:var(--soft);border-top:1px solid var(--line);border-bottom:1px solid var(--line);}
.trust-inner{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;padding:30px 0;text-align:center;}
.trust .t-num{font-size:30px;font-weight:700;color:var(--ink);letter-spacing:-.02em;}
.trust .t-lab{font-size:14px;color:var(--ink-2);margin-top:4px;}

/* ---------- 区块通用 ---------- */
.section{padding:96px 24px;}
.section.soft{background:var(--soft);}
.section-head{text-align:center;max-width:720px;margin:0 auto 56px;}
.section-head .eyebrow{color:var(--brand-deep);font-weight:600;font-size:15px;margin-bottom:14px;}
.section-head h2{font-size:clamp(30px,4.4vw,46px);line-height:1.1;}
.section-head p{color:var(--ink-2);font-size:19px;margin-top:16px;}

/* ---------- 功能 Bento ---------- */
.bento{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;}
.card{
  background:var(--bg);border:1px solid var(--line);border-radius:var(--radius-lg);
  padding:32px;box-shadow:var(--shadow-sm);transition:transform .3s var(--ease),box-shadow .3s;
}
.card:hover{transform:translateY(-4px);box-shadow:var(--shadow-md);}
.card.wide{grid-column:span 2;}
.card .ico{
  width:46px;height:46px;border-radius:12px;display:grid;place-items:center;
  background:linear-gradient(180deg,var(--brand-2),var(--brand));color:#fff;margin-bottom:18px;
}
.card .ico svg{width:24px;height:24px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round;}
.card h3{font-size:21px;margin-bottom:10px;}
.card p{color:var(--ink-2);font-size:15.5px;}

/* ---------- 安全区（深色） ---------- */
.security{background:#0b0b0f;color:#f5f5f7;}
.security .section-head h2{color:#fff;}
.security .section-head p{color:#a1a1a6;}
.sec-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px;max-width:920px;margin:0 auto;}
.sec-item{display:flex;gap:16px;padding:22px;border:1px solid rgba(255,255,255,.10);border-radius:var(--radius);background:rgba(255,255,255,.03);}
.sec-item .si-ico{width:38px;height:38px;flex:0 0 38px;border-radius:10px;background:rgba(41,128,254,.18);color:var(--brand-2);display:grid;place-items:center;}
.sec-item .si-ico svg{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round;}
.sec-item h3{font-size:18px;color:#fff;margin-bottom:6px;}
.sec-item p{color:#a1a1a6;font-size:14.5px;}

/* ---------- 多平台 ---------- */
.platforms{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;}
.plat{
  text-align:center;padding:40px 28px;border:1px solid var(--line);border-radius:var(--radius-lg);
  background:var(--bg);box-shadow:var(--shadow-sm);transition:transform .3s var(--ease),box-shadow .3s;
}
.plat:hover{transform:translateY(-4px);box-shadow:var(--shadow-md);}
.plat .p-ico{width:64px;height:64px;margin:0 auto 18px;border-radius:18px;display:grid;place-items:center;
  background:linear-gradient(180deg,var(--brand-2),var(--brand));color:#fff;}
.plat .p-ico svg{width:32px;height:32px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round;}
.plat h3{font-size:20px;margin-bottom:8px;}
.plat p{color:var(--ink-2);font-size:15px;margin-bottom:18px;}

/* ---------- 下载区 ---------- */
.download{background:var(--soft);}
.dl-grid{display:grid;grid-template-columns:1.1fr .9fr;gap:28px;align-items:stretch;}
.dl-card{
  background:var(--bg);border:1px solid var(--line);border-radius:var(--radius-lg);
  padding:40px;box-shadow:var(--shadow-sm);display:flex;flex-direction:column;
}
.dl-card .dl-badge{display:inline-flex;align-items:center;gap:8px;align-self:flex-start;
  background:rgba(41,128,254,.10);color:var(--brand-deep);font-size:13px;font-weight:600;
  padding:6px 12px;border-radius:999px;margin-bottom:18px;}
.dl-card h3{font-size:26px;margin-bottom:12px;}
.dl-card p{color:var(--ink-2);font-size:15.5px;margin-bottom:24px;}
.dl-card .btn{margin-bottom:12px;}
.dl-meta{font-size:13px;color:var(--ink-3);margin-top:auto;padding-top:18px;border-top:1px solid var(--line);}
.dl-qr{
  background:var(--bg);border:1px solid var(--line);border-radius:var(--radius-lg);
  padding:36px;box-shadow:var(--shadow-sm);text-align:center;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:18px;
}
.dl-qr .qr-img{width:200px;height:200px;border-radius:16px;background:#fff;box-shadow:var(--shadow-sm);}
.dl-qr .qr-cap{font-size:14px;color:var(--ink-2);max-width:24ch;}
.dl-steps{list-style:none;margin:0;padding:0;counter-reset:s;}
.dl-steps li{position:relative;padding-left:40px;margin-bottom:16px;color:var(--ink-2);font-size:15px;}
.dl-steps li::before{
  counter-increment:s;content:counter(s);position:absolute;left:0;top:0;
  width:28px;height:28px;border-radius:50%;background:var(--brand);color:#fff;
  display:grid;place-items:center;font-size:14px;font-weight:700;
}

/* ---------- FAQ ---------- */
.faq{max-width:780px;margin:0 auto;}
.faq-item{border-bottom:1px solid var(--line);padding:22px 0;}
.faq-q{font-size:19px;font-weight:600;margin-bottom:8px;color:var(--ink);}
.faq-a{color:var(--ink-2);font-size:15.5px;}

/* ---------- 页脚 ---------- */
.footer{background:var(--soft);border-top:1px solid var(--line);padding:54px 24px 40px;font-size:13.5px;color:var(--ink-2);}
.footer-inner{max-width:var(--maxw);margin:0 auto;display:flex;flex-wrap:wrap;gap:30px;justify-content:space-between;}
.footer .f-brand img{height:24px;margin-bottom:12px;}
.footer .f-brand p{max-width:30ch;line-height:1.7;}
.footer .f-cols{display:flex;gap:56px;flex-wrap:wrap;}
.footer .f-col h4{font-size:13px;color:var(--ink);margin-bottom:12px;font-weight:600;letter-spacing:.02em;}
.footer .f-col a{display:block;color:var(--ink-2);margin-bottom:9px;font-size:13.5px;}
.footer .f-col a:hover{color:var(--brand-deep);}
.footer .f-risk{max-width:var(--maxw);margin:34px auto 0;padding-top:22px;border-top:1px solid var(--line);
  color:var(--ink-3);line-height:1.7;}
.footer .f-copy{max-width:var(--maxw);margin:16px auto 0;color:var(--ink-3);}

/* ---------- 滚动渐显 ---------- */
.reveal{opacity:0;transform:translateY(24px);transition:opacity .7s var(--ease),transform .7s var(--ease);}
.reveal.in{opacity:1;transform:none;}
@media (prefers-reduced-motion:reduce){
  .reveal{opacity:1;transform:none;transition:none;}
  html{scroll-behavior:auto;}
}

/* ---------- 响应式 ---------- */
@media (max-width:900px){
  .nav-links{display:none;}
  .nav-toggle{display:block;}
  .nav-links.open{
    display:flex;flex-direction:column;position:absolute;top:56px;left:0;right:0;
    background:#fff;border-bottom:1px solid var(--line);padding:18px 24px;gap:16px;align-items:flex-start;
  }
  .bento{grid-template-columns:1fr 1fr;}
  .card.wide{grid-column:span 2;}
  .sec-grid{grid-template-columns:1fr;}
  .platforms{grid-template-columns:1fr;}
  .dl-grid{grid-template-columns:1fr;}
  .trust-inner{grid-template-columns:1fr;gap:14px;}
  .section{padding:64px 20px;}
  .hero{padding:56px 20px 30px;}
}
@media (max-width:560px){
  .bento{grid-template-columns:1fr;}
  .card.wide{grid-column:span 1;}
  body{font-size:16px;}
}