:root {
  --bg: #050505;
  --bg-elev: #0c0c0c;
  --fg: #f5f5f5;
  --muted: #8a8a8a;
  --line: #1f1f1f;
  --cta: #ffffff;
  --cta-fg: #050505;
  --accent: #a3a3a3;
  --brand: #f5f5f5;
  --card: #0c0c0c;
  --text: #f5f5f5;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--fg); text-decoration: none; }
a:hover { opacity: 0.85; }
.wrap { max-width: 960px; margin: 0 auto; padding: 0 24px; }
header {
  position: sticky; top: 0; z-index: 20;
  background: rgba(5,5,5,.82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  min-height: 64px; gap: 16px;
}
.logo { font-weight: 600; font-size: 15px; letter-spacing: 0.02em; }
.logo a { color: var(--fg); text-decoration: none; }
.nav-links { display: flex; gap: 16px; flex-wrap: wrap; font-size: 13px; color: var(--muted); }
.nav-links a { color: var(--muted); }
.nav-links a:hover, .nav-links a.active { color: var(--fg); opacity: 1; }
@media (max-width: 860px) { .nav-links { display: none; } }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 12px 22px; border-radius: 999px;
  font-size: 14px; font-weight: 600; border: none; cursor: pointer;
}
.btn-primary { background: var(--cta); color: var(--cta-fg); }
.btn-primary:hover { opacity: 0.92; }
.btn-ghost {
  background: transparent; color: var(--muted);
  border: 1px solid var(--line); padding: 11px 20px;
}
.btn-ghost:hover { color: var(--fg); border-color: #333; opacity: 1; }
.btn-sm { padding: 8px 16px; font-size: 13px; }
.hero {
  background: var(--bg);
  padding: 56px 0 40px;
  border-bottom: 1px solid var(--line);
}
.hero-grid {
  display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 28px; align-items: center;
}
@media (max-width: 860px) { .hero-grid { grid-template-columns: 1fr; } }
h1 {
  font-size: clamp(26px, 4.5vw, 40px); line-height: 1.25;
  color: var(--fg); margin: 0 0 16px; font-weight: 600; letter-spacing: -0.02em;
}
.lead { font-size: 16px; color: var(--muted); margin: 0 0 22px; }
.cta-row { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 10px; align-items: center; }
.note { font-size: 12px; color: #555; }
.panel {
  background: var(--bg-elev); border-radius: 16px; padding: 18px;
  border: 1px solid var(--line);
}
.panel-visual { padding: 10px; }
.hero-shot, .scene-visual {
  display: block; width: 100%; height: auto; border-radius: 12px;
  border: 1px solid var(--line);
}
section { padding: 48px 0; border-top: 1px solid var(--line); }
h2 { font-size: clamp(20px, 3vw, 26px); color: var(--fg); margin: 0 0 16px; font-weight: 600; }
.grid3 {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px;
}
@media (max-width: 860px) { .grid3 { grid-template-columns: 1fr; } }
.card {
  background: var(--bg-elev); border: 1px solid var(--line); border-radius: 14px;
  padding: 18px 16px;
}
.card h3 { margin: 0 0 8px; font-size: 15px; color: var(--fg); }
.card p { margin: 0; font-size: 14px; color: var(--muted); }
.cap-icon { width: 40px; height: 40px; margin-bottom: 10px; border-radius: 8px; }
.scenes { margin: 0; padding-left: 18px; color: var(--muted); font-size: 14px; }
.scenes li { margin-bottom: 8px; }
.pain-layout {
  display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 24px; align-items: start;
}
@media (max-width: 860px) { .pain-layout { grid-template-columns: 1fr; } }
.compare, .faq-item, details {
  background: var(--bg-elev); border: 1px solid var(--line); border-radius: 12px;
  padding: 16px 18px; color: var(--muted); font-size: 14px; margin-bottom: 12px;
}
.tag-verify {
  display: inline-block; font-size: 11px; color: var(--accent);
  border: 1px solid var(--line); border-radius: 999px; padding: 2px 8px;
}
.hub-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px;
}
@media (max-width: 720px) { .hub-grid { grid-template-columns: 1fr; } }
.hub-card {
  display: block; background: var(--bg-elev); border: 1px solid var(--line);
  border-radius: 16px; padding: 22px 20px; color: inherit;
}
.hub-card:hover { border-color: #333; opacity: 1; }
.hub-card h3 { margin: 0 0 8px; font-size: 16px; color: var(--fg); }
.hub-card p { margin: 0 0 12px; font-size: 14px; color: var(--muted); }
.hub-card .more { font-size: 13px; color: var(--accent); }
footer {
  border-top: 1px solid var(--line);
  padding: 36px 0 48px;
  font-size: 12px; color: #555;
}
footer a { color: #777; }
.foot-title { color: var(--muted); font-weight: 500; margin-bottom: 6px; font-size: 13px; }
.oem-tag {
  display: inline-block; font-size: 11px; letter-spacing: 0.06em;
  color: var(--accent); margin-bottom: 12px;
}

/* force dark body sections (no light mid-page islands) */
.hero, section, .faq, .compare, .steps, .step, .flow span, ul.scenes, .demo-kicker {
  background: transparent;
}
.panel, .card, .hub-card, .esign-block, .faq-item, details, .compare, .step {
  background: var(--bg-elev) !important;
  border-color: var(--line) !important;
  color: var(--muted);
  box-shadow: none !important;
}
.panel h3, .card h3, .step b, .foot-title, strong { color: var(--fg); }
body, .wrap { background: var(--bg); }
img.hero-shot, img.scene-visual, img.cap-icon { background: #111; }
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
@media (max-width: 860px) { .steps { grid-template-columns: 1fr 1fr; } }
.step { background: var(--bg-elev) !important; border-radius: 12px; padding: 14px; border: 1px solid var(--line); font-size: 14px; color: var(--muted); }
.step b { display: block; color: var(--fg); margin-bottom: 6px; }