/* ===== Variables ===== */
:root{
  --blue:#2563EB; --blue-d:#1E40AF; --indigo:#4F46E5;
  --ink:#1D1D1F; --ink2:#3A3A3C; --muted:#6B7280; --dim:#9CA3AF;
  --bg:#F6F7FB; --card:#FFFFFF; --line:#E6E8EE; --accent-soft:#EFF4FF;
  --radius:14px; --radius-sm:10px;
  --shadow:0 6px 24px rgba(30,41,59,.08); --shadow-h:0 12px 36px rgba(37,99,235,.16);
}

/* ===== Reset & Base ===== */
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:"Microsoft YaHei","PingFang SC","Hiragino Sans GB","Segoe UI",sans-serif;
  color:var(--ink); background:var(--bg); line-height:1.65;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none}
.wrap{max-width:1160px;margin:0 auto;padding:0 24px}

/* ===== Buttons ===== */
.btn{
  display:inline-flex;align-items:center;gap:8px;cursor:pointer;
  border:none;border-radius:999px;font-size:15px;font-weight:600;
  padding:12px 26px;transition:.18s;white-space:nowrap;
}
.btn-primary{background:linear-gradient(135deg,var(--blue),var(--indigo));color:#fff;box-shadow:var(--shadow-h)}
.btn-primary:hover{transform:translateY(-2px)}
.btn-ghost{background:rgba(255,255,255,.16);color:#fff;border:1px solid rgba(255,255,255,.4)}
.btn-ghost:hover{background:rgba(255,255,255,.28)}
.btn-line{background:#fff;color:var(--blue);border:1px solid #fff;box-shadow:0 8px 24px rgba(0,0,0,.14)}
.btn-line:hover{transform:translateY(-2px);box-shadow:0 12px 32px rgba(0,0,0,.20)}

/* ===== Top Nav ===== */
header.nav{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);
  backdrop-filter:saturate(160%) blur(10px);border-bottom:1px solid var(--line)}
.nav-inner{display:flex;align-items:center;height:64px}
.logo{display:flex;align-items:center;gap:10px;font-weight:800;font-size:20px;color:var(--ink)}
.logo .mark{width:30px;height:30px;border-radius:8px;background:linear-gradient(135deg,var(--blue),var(--indigo));
  color:#fff;display:flex;align-items:center;justify-content:center;font-size:16px;font-weight:800}
nav.menu{margin-left:auto;display:flex;align-items:center;gap:30px}
nav.menu a{color:var(--ink2);font-size:15px;font-weight:500;transition:.15s}
nav.menu a:hover{color:var(--blue)}
nav.menu a.active{color:var(--blue)}
.nav .btn{padding:9px 20px;font-size:14px;margin-left:18px}

/* ===== Page Header (sub-page hero) ===== */
.page-header{background:radial-gradient(1200px 400px at 50% -10%,rgba(79,70,229,.35),transparent),
  linear-gradient(135deg,#1E3A8A,#2563EB 55%,#4F46E5);color:#fff;padding:64px 0 70px;text-align:center;position:relative;overflow:hidden}
.page-header h1{font-size:38px;font-weight:800;margin-bottom:14px;letter-spacing:.5px}
.page-header p{font-size:17px;opacity:.92;max-width:640px;margin:0 auto}
.breadcrumb{padding:14px 0;background:#fff;border-bottom:1px solid var(--line);font-size:13.5px;color:var(--muted)}
.breadcrumb a{color:var(--muted)}
.breadcrumb a:hover{color:var(--blue)}
.breadcrumb .sep{margin:0 8px;color:var(--dim)}

/* ===== Section ===== */
section{padding:74px 0}
.sec-head{text-align:center;max-width:720px;margin:0 auto 46px}
.sec-head .kicker{color:var(--blue);font-weight:700;font-size:14px;letter-spacing:2px}
.sec-head h2{font-size:32px;font-weight:800;margin:10px 0 12px}
.sec-head p{color:var(--muted);font-size:16px}

.grid{display:grid;gap:20px}
.grid.f2{grid-template-columns:repeat(2,1fr)}
.grid.f3{grid-template-columns:repeat(3,1fr)}

.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:28px 26px;box-shadow:var(--shadow);transition:.18s}
.card:hover{transform:translateY(-4px);box-shadow:var(--shadow-h);border-color:#C9D6FF}

/* ===== Footer ===== */
footer{background:#0F172A;color:#C7CEDA;padding:48px 0 26px;margin-top:74px}
.foot-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:30px}
footer h4{color:#fff;font-size:15px;margin-bottom:14px}
footer a{color:#9FB0C7;font-size:14px;display:block;padding:5px 0}
footer a:hover{color:#fff}
.foot-logo{display:flex;align-items:center;gap:10px;font-weight:800;color:#fff;font-size:20px;margin-bottom:12px}
.foot-logo .mark{width:30px;height:30px;border-radius:8px;background:linear-gradient(135deg,var(--blue),var(--indigo));
  color:#fff;display:flex;align-items:center;justify-content:center;font-weight:800}
footer .desc{font-size:13.5px;color:#8C9AB0;max-width:300px}
.foot-bottom{border-top:1px solid #1E293B;margin-top:30px;padding-top:18px;text-align:center;
  font-size:13px;color:#7C8AA0;display:flex;flex-direction:column;gap:6px}
.foot-bottom a{display:inline;color:#9FB0C7}

/* ===== Back to Top ===== */
#toTop{position:fixed;right:24px;bottom:28px;width:46px;height:46px;border-radius:50%;
  background:linear-gradient(135deg,var(--blue),var(--indigo));color:#fff;border:none;cursor:pointer;
  font-size:20px;box-shadow:var(--shadow-h);opacity:0;visibility:hidden;transition:.25s;z-index:60}
#toTop.show{opacity:1;visibility:visible}

/* ===== Free Banner ===== */
.free-banner{
  background:linear-gradient(135deg,#EFF4FF 0%,#F0F4FF 100%);
  border-top:1px solid #DDE6FF;
  border-bottom:1px solid #DDE6FF;
  padding:24px 0;
}
.free-inner{
  display:flex;align-items:center;gap:28px;
  background:#fff;border-radius:14px;
  padding:20px 28px;box-shadow:0 2px 12px rgba(37,99,235,.08);
}
.free-icon{
  width:52px;height:52px;flex-shrink:0;
  background:linear-gradient(135deg,#2563EB,#4F46E5);
  color:#fff;border-radius:14px;
  display:flex;align-items:center;justify-content:center;
}
.free-icon svg{width:26px;height:26px}
.free-text{flex:1}
.free-text h3{font-size:18px;font-weight:800;color:var(--ink);margin-bottom:6px}
.free-text p{color:var(--muted);font-size:14.5px;line-height:1.7;margin:0}
.free-text strong{color:#2563EB;font-weight:700}

/* ===== Responsive ===== */
@media(max-width:920px){
  .grid.f3,.grid.f2{grid-template-columns:1fr}
  .foot-grid{grid-template-columns:1fr 1fr}
  nav.menu{display:none}
  .page-header h1{font-size:30px}
  .free-inner{flex-direction:column;text-align:center;padding:18px 20px}
}