:root {
  color-scheme: light;
  --bg: #fff;
  --ink: #0a0a0a;
  --muted: #666;
  --line: #e9e9e9;
  --soft: #f7f7f7;
  --danger: #c52b24;
  --radius: 22px;
  --max: 1160px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", "PingFang SC", "PingFang TC", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.55;
}

body { margin: 0; }

a { color: inherit; text-underline-offset: 4px; }

.cn, .en { display: none; }
html[data-lang="zh"] .cn { display: inline; }
html[data-lang="zh"] .cn.block { display: block; }
html[data-lang="en"] .en { display: inline; }
html[data-lang="en"] .en.block { display: block; }
html[data-lang="zh"] .shot-en,
html[data-lang="en"] .shot-cn { display: none; }

.shell {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255,255,255,.9);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--line);
}

.topbar-inner {
  height: 74px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  font-weight: 850;
}

.logo {
  width: 34px;
  height: 34px;
  border: 2px solid var(--ink);
  border-radius: 10px;
  position: relative;
  flex: 0 0 auto;
}

.logo::before {
  content: "";
  position: absolute;
  left: 8px;
  right: 8px;
  top: -12px;
  height: 17px;
  border: 2px solid var(--ink);
  border-bottom: 0;
  border-radius: 14px 14px 0 0;
  background: var(--bg);
}

.logo::after {
  content: "";
  width: 7px;
  height: 13px;
  background: var(--ink);
  border-radius: 9px;
  position: absolute;
  left: 50%;
  top: 52%;
  transform: translate(-50%, -20%);
}

.nav {
  display: flex;
  align-items: center;
  gap: 18px;
  color: var(--muted);
  font-size: 15px;
}

.nav a {
  text-decoration: none;
}

.lang-switch {
  border: 1px solid var(--ink);
  background: var(--bg);
  color: var(--ink);
  border-radius: 999px;
  padding: 7px 12px;
  min-height: 38px;
  font: inherit;
  font-weight: 750;
  cursor: pointer;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(330px, 450px);
  gap: clamp(36px, 7vw, 96px);
  align-items: center;
  padding: clamp(54px, 8vw, 102px) 0 76px;
}

.eyebrow {
  margin: 0 0 18px;
  color: var(--muted);
  font-weight: 750;
}

h1 {
  margin: 0;
  max-width: 760px;
  font-size: clamp(48px, 7vw, 94px);
  line-height: .96;
  letter-spacing: 0;
}

.lead {
  margin: 24px 0 0;
  max-width: 720px;
  color: var(--muted);
  font-size: clamp(18px, 2.2vw, 25px);
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 20px;
  border: 1.5px solid var(--ink);
  border-radius: 999px;
  text-decoration: none;
  font-weight: 800;
  background: var(--bg);
}

.btn.secondary {
  color: var(--muted);
  border-color: var(--line);
}

.hero-visual {
  justify-self: center;
  width: min(100%, 420px);
}

.hero-visual img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 28px;
  box-shadow: 0 24px 70px rgba(0,0,0,.12);
}

.section {
  padding: 74px 0;
  border-top: 1px solid var(--line);
}

.section-head {
  display: grid;
  grid-template-columns: minmax(0, 420px) minmax(0, 1fr);
  gap: 32px;
  align-items: end;
  margin-bottom: 30px;
}

h2 {
  margin: 0;
  font-size: clamp(32px, 4.2vw, 56px);
  line-height: 1;
  letter-spacing: 0;
}

.section-head p {
  margin: 0;
  color: var(--muted);
  font-size: 18px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.card {
  padding: 24px;
  min-height: 190px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg);
}

.card strong {
  display: block;
  font-size: 22px;
  margin-bottom: 10px;
}

.card p {
  margin: 0;
  color: var(--muted);
}

.privacy-band {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(280px, .85fr);
  gap: 28px;
  padding: 34px;
  border: 1.5px solid var(--ink);
  border-radius: 28px;
  background: var(--soft);
}

.privacy-band p {
  margin: 0;
  color: var(--muted);
  font-size: 18px;
}

.checklist {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.checklist li {
  padding-left: 28px;
  position: relative;
  font-weight: 750;
}

.checklist li::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 999px;
  background: var(--ink);
  position: absolute;
  left: 4px;
  top: .72em;
}

.faq {
  display: grid;
  gap: 10px;
}

details {
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 18px 20px;
}

summary {
  cursor: pointer;
  font-weight: 850;
}

details p {
  margin: 12px 0 0;
  color: var(--muted);
}

.footer {
  border-top: 1px solid var(--line);
  padding: 30px 0 50px;
  color: var(--muted);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.footer-links {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

@media (max-width: 860px) {
  .nav a { display: none; }
  .hero {
    grid-template-columns: 1fr;
    padding-top: 46px;
  }
  .hero-visual {
    width: min(100%, 360px);
  }
  .section-head,
  .privacy-band {
    grid-template-columns: 1fr;
  }
  .grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 520px) {
  .shell { width: min(100% - 28px, var(--max)); }
  .topbar-inner { height: 66px; }
  .brand span:last-child { max-width: 142px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
  .hero { padding-bottom: 54px; }
  .section { padding: 56px 0; }
  .privacy-band { padding: 24px; }
  .cta-row .btn { width: 100%; }
}