:root {
  --bg: #f7f9fc;
  --bg-soft: #eef2f8;
  --surface: rgba(15, 23, 42, 0.04);
  --surface-2: rgba(15, 23, 42, 0.07);
  --border: rgba(15, 23, 42, 0.1);
  --text: #0f172a;
  --text-dim: #475569;
  --text-faint: #94a3b8;
  --accent: #1d4ed8;
  --accent-2: #1e40af;
  --accent-soft: rgba(29, 78, 216, 0.08);
  --accent-deep: #0f172a;
  --radius: 18px;
  --max: 1080px;
  font-family: "Inter", "Noto Sans SC", system-ui, -apple-system, sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { font-weight: 700; letter-spacing: -0.02em; }

/* Background orbs */
.bg-orbs { position: fixed; inset: 0; z-index: 0; pointer-events: none; overflow: hidden; }
.orb { position: absolute; border-radius: 50%; filter: blur(110px); opacity: 0.16; }
.orb-1 { width: 540px; height: 540px; background: #bfdbfe; top: -180px; left: -120px; }
.orb-2 { width: 480px; height: 480px; background: #c7d2fe; top: 30%; right: -140px; opacity: 0.14; }
.orb-3 { width: 420px; height: 420px; background: #ddd6fe; bottom: -140px; left: 35%; opacity: 0.12; }

/* Nav */
.nav {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px; padding: 16px 32px;
  backdrop-filter: blur(14px);
  background: rgba(247, 249, 252, 0.78);
  border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 9px; font-weight: 700; font-size: 18px; }
.brand-mark {
  display: inline-flex; align-items: center; justify-content: center;
  width: 30px; height: 30px; border-radius: 9px;
  background: var(--accent-deep);
  color: #fff; font-size: 16px; font-weight: 800;
}
.nav-links { display: flex; gap: 26px; font-size: 14.5px; color: var(--text-dim); }
.nav-links a { transition: color 0.18s; }
.nav-links a:hover { color: var(--text); }
.nav-right { display: flex; align-items: center; gap: 12px; }

.lang-toggle {
  border: 1px solid var(--border); background: var(--surface);
  color: var(--text-dim); border-radius: 10px; padding: 6px 11px;
  font-size: 13px; cursor: pointer; transition: all 0.18s; font-family: inherit;
}
.lang-toggle:hover { color: var(--text); border-color: var(--accent); }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 11px; padding: 9px 16px; font-size: 14.5px; font-weight: 600;
  cursor: pointer; transition: all 0.18s; border: 1px solid transparent; font-family: inherit;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-2); transform: translateY(-1px); }
.btn-ghost { background: var(--surface); border-color: var(--border); color: var(--text); }
.btn-ghost:hover { background: var(--surface-2); border-color: var(--accent); }
.btn-lg { padding: 13px 26px; font-size: 16px; border-radius: 13px; }

/* Hero */
main { position: relative; z-index: 1; }
.hero { display: flex; justify-content: center; padding: 110px 24px 80px; }
.hero-inner { max-width: 820px; text-align: center; }
.badge {
  display: inline-block; padding: 7px 15px; font-size: 13px; font-weight: 500;
  color: var(--accent); background: var(--accent-soft);
  border: 1px solid rgba(29, 78, 216, 0.2); border-radius: 999px; margin-bottom: 26px;
}
.hero-title { font-size: clamp(38px, 6vw, 62px); line-height: 1.1; font-weight: 800; }
.hero-title .accent {
  background: linear-gradient(120deg, #1d4ed8, #6d28d9);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-sub {
  margin: 26px auto 0; max-width: 700px;
  font-size: 17.5px; color: var(--text-dim); line-height: 1.7;
}
.hero-cta { display: flex; gap: 14px; justify-content: center; margin-top: 36px; flex-wrap: wrap; }
.hero-meta { margin-top: 28px; font-size: 13.5px; color: var(--text-faint); }
.hero-meta .dot { margin: 0 10px; }

/* Sections */
.section { max-width: var(--max); margin: 0 auto; padding: 70px 24px; }
.section-head { text-align: center; margin-bottom: 46px; }
.section-head h2 { font-size: clamp(28px, 4vw, 38px); }
.section-head p { margin-top: 14px; color: var(--text-dim); font-size: 16px; }

/* Cards */
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.arch-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 26px 22px; transition: all 0.2s;
}
.card:hover { transform: translateY(-4px); border-color: rgba(29, 78, 216, 0.35); background: var(--surface-2); }
.card-icon {
  width: 44px; height: 44px; border-radius: 12px; display: flex; align-items: center; justify-content: center;
  background: var(--accent-soft); color: var(--accent); font-size: 22px; margin-bottom: 16px;
}
.card h3 { font-size: 18px; margin-bottom: 9px; }
.card p { color: var(--text-dim); font-size: 14.5px; }

/* Steps */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.step {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px 20px; position: relative;
}
.step-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; border-radius: 10px; font-weight: 700; font-size: 15px;
  background: var(--accent); color: #fff; margin-bottom: 14px;
}
.step h4 { font-size: 16.5px; margin-bottom: 8px; }
.step p { color: var(--text-dim); font-size: 14px; }

/* Model table */
.model-table {
  border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden;
  background: var(--surface);
}
.model-row {
  display: grid; grid-template-columns: 1.1fr 2.2fr 2fr; gap: 16px;
  padding: 18px 22px; border-bottom: 1px solid var(--border); align-items: center;
}
.model-row:last-child { border-bottom: none; }
.model-head { background: var(--surface-2); font-weight: 600; color: var(--text-dim); font-size: 13.5px; }
.model-use {
  font-size: 13px; font-weight: 600; color: var(--accent);
  background: var(--accent-soft); padding: 4px 10px; border-radius: 8px; justify-self: start;
}
.model-name { font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: 13.5px; color: var(--text); word-break: break-word; }
.model-foot { margin-top: 16px; font-size: 13.5px; color: var(--text-faint); text-align: center; }

/* CTA */
.cta-section { padding-top: 30px; }
.cta-card {
  background: var(--accent-deep); color: #fff; border-radius: 24px;
  padding: 54px 40px; text-align: center;
}
.cta-card h2 { font-size: clamp(26px, 4vw, 36px); }
.cta-card p { margin-top: 14px; color: rgba(255, 255, 255, 0.72); font-size: 16px; }
.cta-card .hero-cta { margin-top: 30px; }
.cta-card .btn-primary { background: #fff; color: var(--accent-deep); }
.cta-card .btn-primary:hover { background: #e2e8f0; }
.cta-card .btn-ghost { background: rgba(255, 255, 255, 0.1); border-color: rgba(255, 255, 255, 0.25); color: #fff; }
.cta-card .btn-ghost:hover { background: rgba(255, 255, 255, 0.18); border-color: rgba(255, 255, 255, 0.5); }
.dl-hint { margin-top: 20px; font-size: 13px; color: rgba(255, 255, 255, 0.55) !important; }

.platform-tags { display: flex; justify-content: center; gap: 10px; margin-top: 26px; flex-wrap: wrap; }
.platform-tag {
  font-size: 13px; padding: 6px 14px; border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.25); color: rgba(255, 255, 255, 0.8);
}
.platform-tag.active { background: rgba(255, 255, 255, 0.14); color: #fff; border-color: rgba(255, 255, 255, 0.45); }
.platform-tag.soon { opacity: 0.55; }

/* Usage list */
.usage-list { display: grid; gap: 14px; }
.usage-item {
  display: flex; gap: 18px; background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--radius); padding: 22px 24px;
  transition: all 0.2s;
}
.usage-item:hover { border-color: rgba(29, 78, 216, 0.3); background: var(--surface-2); }
.usage-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 36px; height: 36px; border-radius: 10px; flex-shrink: 0;
  background: var(--accent); color: #fff; font-weight: 700; font-size: 16px;
}
.usage-body h4 { font-size: 17px; margin-bottom: 6px; }
.usage-body p { color: var(--text-dim); font-size: 14.5px; }

/* FAQ */
.faq-list { display: grid; gap: 12px; max-width: 760px; margin: 0 auto; }
.faq-item {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 14px; overflow: hidden; transition: border-color 0.2s;
}
.faq-item:hover { border-color: rgba(29, 78, 216, 0.3); }
.faq-item summary {
  list-style: none; cursor: pointer; padding: 18px 22px;
  font-weight: 600; font-size: 15.5px; display: flex; align-items: center; gap: 10px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::before {
  content: "+"; font-weight: 700; color: var(--accent); font-size: 18px;
  transition: transform 0.2s; line-height: 1;
}
.faq-item[open] summary::before { transform: rotate(45deg); }
.faq-item p { padding: 0 22px 18px; color: var(--text-dim); font-size: 14.5px; }

/* Footer */
.footer {
  position: relative; z-index: 1; border-top: 1px solid var(--border);
  padding: 32px; display: flex; align-items: center; justify-content: space-between;
  gap: 20px; flex-wrap: wrap; background: rgba(247, 249, 252, 0.6);
}
.footer-left p { margin-top: 6px; color: var(--text-faint); font-size: 13.5px; }
.footer-links { display: flex; gap: 22px; font-size: 14px; color: var(--text-dim); }
.footer-links a:hover { color: var(--text); }

/* Scroll reveal */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.in { opacity: 1; transform: none; }

/* Responsive */
@media (max-width: 900px) {
  .card-grid, .arch-grid { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); }
  .nav-links { display: none; }
}
@media (max-width: 600px) {
  .card-grid, .arch-grid { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
  .model-row { grid-template-columns: 1fr; gap: 8px; }
  .nav { padding: 14px 18px; }
  .hero { padding: 80px 20px 60px; }
  .section { padding: 56px 18px; }
  .cta-card { padding: 40px 22px; }
  .usage-item { flex-direction: column; gap: 10px; }
}