:root {
  --bg: #0b1020;
  --bg-alt: #11182e;
  --surface: #161f3a;
  --surface-2: #1d294a;
  --text: #e8edf7;
  --muted: #9aa7c4;
  --primary: #4f7cff;
  --primary-2: #6d9bff;
  --accent: #21d4a8;
  --border: rgba(255,255,255,.08);
  --radius: 16px;
  --shadow: 0 10px 40px rgba(0,0,0,.35);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

.container {
  width: 100%;
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
}
.container-narrow { max-width: 760px; }

/* Buttons */
.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 15px;
  transition: transform .15s ease, box-shadow .2s ease, background .2s ease;
  cursor: pointer;
  border: 1px solid transparent;
  text-align: center;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: #fff;
  box-shadow: 0 8px 24px rgba(79,124,255,.35);
}
.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}
.btn-ghost:hover { background: var(--surface); }
.btn-lg { padding: 15px 32px; font-size: 16px; }
.btn-block { display: block; width: 100%; }

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(11,16,32,.82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 68px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 800;
  font-size: 19px;
}
.brand-icon { font-size: 22px; }
.nav-links {
  display: flex;
  gap: 28px;
  margin-left: auto;
  font-size: 15px;
  color: var(--muted);
}
.nav-links a:hover { color: var(--text); }
.nav-cta { margin-left: 4px; }

/* Hero */
.hero {
  position: relative;
  padding: 96px 0 80px;
  background:
    radial-gradient(900px 500px at 70% -10%, rgba(79,124,255,.25), transparent 60%),
    radial-gradient(700px 400px at 10% 10%, rgba(33,212,168,.16), transparent 55%);
  text-align: center;
}
.hero-inner { max-width: 820px; margin: 0 auto; }
.hero h1 {
  font-size: clamp(30px, 5vw, 50px);
  line-height: 1.2;
  font-weight: 800;
  letter-spacing: -.5px;
}
.hero-sub {
  margin: 22px auto 0;
  max-width: 640px;
  font-size: clamp(16px, 2.2vw, 19px);
  color: var(--muted);
}
.hero-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  margin-top: 34px;
  flex-wrap: wrap;
}
.hero-stats {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-top: 56px;
}
.hero-stats li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 12px;
}
.hero-stats strong {
  display: block;
  font-size: 26px;
  font-weight: 800;
  color: var(--primary-2);
}
.hero-stats span { font-size: 13px; color: var(--muted); }

/* Sections */
.section { padding: 84px 0; }
.section-alt { background: var(--bg-alt); }
.section-title {
  text-align: center;
  font-size: clamp(24px, 3.5vw, 34px);
  font-weight: 800;
}
.section-lead {
  text-align: center;
  color: var(--muted);
  max-width: 600px;
  margin: 14px auto 48px;
}

/* Prose (long-form content) */
.prose { text-align: left; }
.prose .section-title { text-align: center; }
.prose h3 {
  font-size: 21px;
  font-weight: 700;
  margin: 36px 0 12px;
}
.prose p {
  color: var(--muted);
  margin-bottom: 16px;
  font-size: 16px;
}
.prose strong { color: var(--text); }

/* Steps (tutorial) */
.steps {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 22px;
  counter-reset: step;
}
.steps li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 22px;
  position: relative;
}
.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: #fff;
  font-weight: 800;
  font-size: 18px;
  margin-bottom: 14px;
}
.steps h3 { font-size: 18px; margin-bottom: 8px; }
.steps p { color: var(--muted); font-size: 14px; }

/* Grids */
.grid { display: grid; gap: 22px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* Cards */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: transform .2s ease, border-color .2s ease;
}
.card:hover { transform: translateY(-4px); border-color: rgba(79,124,255,.5); }
.card-icon { font-size: 30px; margin-bottom: 14px; }
.card h3 { font-size: 19px; margin-bottom: 8px; }
.card p { color: var(--muted); font-size: 15px; }

/* Nodes */
.node {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  text-align: center;
  font-weight: 600;
  transition: border-color .2s ease, background .2s ease;
}
.node:hover { border-color: var(--accent); background: var(--surface-2); }

/* Downloads */
.downloads { max-width: 920px; margin: 0 auto; }
.dl-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 18px;
  transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease;
}
.dl-card:hover {
  transform: translateY(-4px);
  border-color: var(--primary);
  box-shadow: 0 14px 40px rgba(79,124,255,.22);
}
.dl-icon { font-size: 40px; margin-bottom: 12px; }
.dl-card h3 { font-size: 19px; }
.dl-meta {
  margin-top: 6px;
  font-size: 13px;
  color: var(--muted);
}

/* FAQ */
.faq details {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 4px 20px;
  margin-bottom: 14px;
}
.faq summary {
  cursor: pointer;
  font-weight: 600;
  padding: 16px 0;
  list-style: none;
  position: relative;
  padding-right: 28px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+";
  position: absolute;
  right: 0;
  top: 14px;
  font-size: 22px;
  color: var(--primary-2);
  transition: transform .2s ease;
}
.faq details[open] summary::after { transform: rotate(45deg); }
.faq details p { padding: 0 0 18px; color: var(--muted); }

/* CTA band */
.cta-band {
  text-align: center;
  padding: 80px 0;
  background:
    radial-gradient(700px 320px at 50% 120%, rgba(79,124,255,.28), transparent 60%),
    var(--bg-alt);
}
.cta-band h2 { font-size: clamp(24px, 3.5vw, 32px); font-weight: 800; }
.cta-band p { color: var(--muted); margin: 14px 0 28px; }

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding-top: 48px;
  background: var(--bg);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px;
  padding-bottom: 32px;
}
.footer-brand p { color: var(--muted); margin-top: 10px; font-size: 14px; }
.footer-links { display: flex; gap: 24px; flex-wrap: wrap; color: var(--muted); }
.footer-links a:hover { color: var(--text); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 20px 24px;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
}

/* Responsive */
@media (max-width: 900px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 720px) {
  .nav-links { display: none; }
  .hero-stats { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 560px) {
  .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
}

/* friendly links */
.flinks{background:var(--bg-alt);border-top:1px solid var(--border);padding:34px 0}.flinks h2{font-size:15px;color:var(--muted);margin-bottom:14px;font-weight:600}.flinks-list{display:flex;flex-wrap:wrap;gap:10px 22px}.flinks-list a{color:var(--primary-2);font-size:14px}.flinks-list a:hover{text-decoration:underline}

/* hero quick-download row */
.hero-dl{display:flex;flex-wrap:wrap;gap:14px;margin:34px auto 38px;justify-content:center}.hdl{display:inline-flex;align-items:center;gap:8px;padding:14px 26px;border-radius:10px;border:1.5px solid var(--primary);color:var(--primary-2);font-weight:700;font-size:15px;background:rgba(79,124,255,.06);transition:.15s}.hdl span{font-size:18px}.hdl:hover{background:var(--primary);color:#fff}

.brand-logo{width:32px;height:32px;border-radius:8px;object-fit:contain;vertical-align:middle}