:root {
  --fg: #15202b;
  --fg-soft: #536471;
  --fg-faint: #8899a6;
  --bg: #ffffff;
  --bg-soft: #f7f9fa;
  --line: #eff3f4;
  --accent: #1d9bf0;
  --accent-2: #7c3aed;
  --accent-grad: linear-gradient(90deg, var(--accent), var(--accent-2));
  --radius: 10px;
  --radius-lg: 14px;
  --shadow: 0 1px 2px rgba(15, 20, 25, 0.04), 0 4px 12px rgba(15, 20, 25, 0.04);
  --max: 760px;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #e7e9ea;
    --fg-soft: #8b98a5;
    --fg-faint: #71767b;
    --bg: #15202b;
    --bg-soft: #1e2732;
    --line: #2f3b46;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.2), 0 4px 12px rgba(0, 0, 0, 0.3);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
        "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: var(--max); margin: 0 auto; padding: 0 24px; }

/* Header */
header.site {
  padding: 20px 24px;
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  z-index: 10;
}
@media (prefers-color-scheme: dark) {
  header.site { background: rgba(21, 32, 43, 0.85); }
}
header.site .brand {
  font-weight: 700;
  font-size: 14.5px;
  letter-spacing: -0.01em;
  color: var(--fg);
  text-decoration: none;
}
header.site .brand .dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-grad);
  margin-right: 8px;
  vertical-align: middle;
}
header.site nav {
  display: flex;
  gap: 20px;
  align-items: center;
  font-size: 13.5px;
}
header.site nav a {
  color: var(--fg-soft);
  text-decoration: none;
}
header.site nav a:hover { color: var(--fg); }
.lang-toggle {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 4px 10px;
  font-size: 12px;
  color: var(--fg-soft);
  background: var(--bg);
  cursor: pointer;
}
.lang-toggle:hover { color: var(--fg); border-color: var(--fg-soft); }

/* Hero */
.hero {
  padding: 88px 24px 64px;
  text-align: center;
}
.hero h1 {
  font-size: clamp(34px, 6vw, 56px);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0 0 18px;
  font-weight: 800;
}
.hero h1 .accent {
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero .tagline {
  font-size: clamp(16px, 2.4vw, 19px);
  color: var(--fg-soft);
  max-width: 560px;
  margin: 0 auto 32px;
  line-height: 1.55;
}
.cta-row {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 14.5px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.12s ease, box-shadow 0.12s ease;
  text-decoration: none;
}
.btn-primary {
  background: var(--fg);
  color: var(--bg);
}
.btn-primary:hover {
  text-decoration: none;
  background: var(--accent);
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}
.btn-ghost {
  background: transparent;
  color: var(--fg);
  border-color: var(--line);
}
.btn-ghost:hover {
  text-decoration: none;
  border-color: var(--fg-soft);
}

/* Sections */
section { padding: 64px 24px; }
section.alt { background: var(--bg-soft); }
section h2 {
  font-size: clamp(24px, 4vw, 32px);
  letter-spacing: -0.015em;
  margin: 0 0 12px;
  font-weight: 700;
}
section .lead {
  color: var(--fg-soft);
  max-width: 520px;
  margin: 0 0 36px;
  font-size: 15px;
}

/* Features grid */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  max-width: var(--max);
  margin: 0 auto;
}
.feature {
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--bg);
}
.feature h3 {
  margin: 0 0 6px;
  font-size: 15.5px;
  font-weight: 600;
}
.feature p {
  margin: 0;
  color: var(--fg-soft);
  font-size: 14px;
  line-height: 1.55;
}
.feature .icon {
  font-size: 22px;
  margin-bottom: 10px;
  display: inline-block;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* Pricing */
.price-card {
  max-width: 460px;
  margin: 0 auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 30px 28px;
  text-align: center;
  background: var(--bg);
  box-shadow: var(--shadow);
}
.price-card .badge {
  display: inline-block;
  background: var(--accent-grad);
  color: #fff;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 16px;
}
.price-card .amount {
  font-size: 56px;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1;
}
.price-card .amount .currency {
  font-size: 28px;
  vertical-align: top;
  font-weight: 700;
  margin-right: 4px;
  color: var(--fg-soft);
}
.price-card .period {
  display: block;
  margin: 6px 0 24px;
  color: var(--fg-soft);
  font-size: 13px;
}
.price-card ul {
  list-style: none;
  padding: 0;
  margin: 0 0 24px;
  text-align: left;
}
.price-card li {
  padding: 6px 0;
  font-size: 14.5px;
  display: flex;
  align-items: flex-start;
  gap: 8px;
}
.price-card li::before {
  content: "✓";
  color: var(--accent);
  font-weight: 700;
}
.price-card .later {
  margin-top: 14px;
  font-size: 12px;
  color: var(--fg-faint);
}

/* CN section */
.cn-card {
  max-width: 520px;
  margin: 32px auto 0;
  padding: 24px;
  border: 1px dashed var(--line);
  border-radius: var(--radius-lg);
  text-align: center;
}
.cn-card h3 { margin: 0 0 10px; font-size: 16px; font-weight: 600; }
.cn-card p { margin: 0 0 16px; font-size: 14px; color: var(--fg-soft); line-height: 1.6; }
.cn-card img {
  width: 200px;
  height: 200px;
  border-radius: var(--radius);
  background: #fff;
  padding: 8px;
  display: block;
  margin: 0 auto;
}
.cn-card .qr-note {
  font-size: 12px;
  color: var(--fg-faint);
  margin-top: 10px;
}

/* FAQ */
.faq { max-width: var(--max); margin: 0 auto; }
.faq details {
  border-bottom: 1px solid var(--line);
  padding: 18px 0;
}
.faq details:last-child { border-bottom: none; }
.faq summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 15px;
  color: var(--fg);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+";
  color: var(--fg-soft);
  font-weight: 400;
  font-size: 22px;
  line-height: 1;
}
.faq details[open] summary::after { content: "−"; }
.faq .answer {
  margin-top: 10px;
  color: var(--fg-soft);
  font-size: 14.5px;
  line-height: 1.7;
}
.faq .answer code, kbd {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
  background: var(--bg-soft);
  padding: 2px 6px;
  border-radius: 4px;
}

/* Footer */
footer.site {
  padding: 40px 24px 60px;
  border-top: 1px solid var(--line);
  text-align: center;
  font-size: 13px;
  color: var(--fg-soft);
}
footer.site .links {
  margin-bottom: 14px;
  display: flex;
  gap: 18px;
  justify-content: center;
  flex-wrap: wrap;
}
footer.site .links a { color: var(--fg-soft); }
footer.site .links a:hover { color: var(--fg); }

/* Doc page (privacy / terms) */
.doc {
  max-width: var(--max);
  margin: 0 auto;
  padding: 64px 24px 80px;
}
.doc h1 {
  font-size: 32px;
  letter-spacing: -0.01em;
  margin: 0 0 8px;
}
.doc .updated {
  color: var(--fg-faint);
  font-size: 13px;
  margin-bottom: 32px;
}
.doc h2 {
  font-size: 18px;
  margin: 32px 0 10px;
  font-weight: 700;
}
.doc p, .doc li {
  font-size: 15px;
  line-height: 1.7;
  color: var(--fg);
}
.doc ul { padding-left: 24px; }
.doc strong { color: var(--fg); }

/* Lang switching */
[lang-zh], [lang-en] { display: none; }
html[data-lang="zh"] [lang-zh] { display: revert; }
html[data-lang="en"] [lang-en] { display: revert; }

/* ─── Mobile (≤600px) ────────────────────────────────────────────── */
@media (max-width: 600px) {
  body { font-size: 15px; }

  /* Header: tighten gaps, allow brand to truncate */
  header.site {
    padding: 14px 16px;
    gap: 8px;
  }
  header.site .brand {
    font-size: 13px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    flex: 1;
    min-width: 0;
  }
  header.site nav {
    gap: 12px;
    font-size: 12.5px;
  }
  /* Hide secondary nav links on phones; keep lang toggle always */
  header.site nav a { display: none; }
  header.site nav .lang-toggle { display: inline-block; }

  /* Hero: tighter padding + tagline */
  .hero {
    padding: 56px 20px 44px;
  }
  .hero h1 {
    font-size: 32px;
    letter-spacing: -0.015em;
    margin-bottom: 14px;
  }
  .hero .tagline {
    font-size: 15px;
    margin-bottom: 24px;
  }
  .cta-row {
    gap: 10px;
  }
  .btn {
    padding: 11px 18px;
    font-size: 14px;
  }
  .btn-primary, .btn-ghost {
    flex: 1;
    min-width: 140px;
  }

  /* Sections: cut vertical breathing room */
  section { padding: 44px 20px; }
  section h2 { font-size: 22px; }
  section .lead { font-size: 14px; margin-bottom: 28px; }

  /* Features: 1 column on phones */
  .features {
    grid-template-columns: 1fr;
    gap: 12px;
  }
  .feature {
    padding: 18px;
  }
  .feature h3 { font-size: 15px; }
  .feature p { font-size: 13.5px; }

  /* Pricing card: less padding, price size down */
  .price-card {
    padding: 24px 20px;
  }
  .price-card .amount {
    font-size: 44px;
  }
  .price-card .amount .currency {
    font-size: 22px;
  }
  .price-card li {
    font-size: 14px;
  }

  /* CN card: shrink QR on phone */
  .cn-card {
    padding: 20px 16px;
    margin-top: 24px;
  }
  .cn-card img {
    width: 160px;
    height: 160px;
  }
  .cn-card p { font-size: 13.5px; }

  /* FAQ: tighter padding */
  .faq details {
    padding: 14px 0;
  }
  .faq summary {
    font-size: 14.5px;
  }
  .faq .answer {
    font-size: 14px;
  }

  /* Footer: stack links + reduce padding */
  footer.site {
    padding: 32px 20px 44px;
  }
  footer.site .links {
    gap: 14px;
    font-size: 12.5px;
  }

  /* Doc page (privacy/terms): mobile-friendly headings */
  .doc {
    padding: 44px 20px 60px;
  }
  .doc h1 { font-size: 26px; }
  .doc h2 { font-size: 16px; margin-top: 26px; }
  .doc p, .doc li { font-size: 14.5px; line-height: 1.65; }
}

/* Tighter still (≤380px — small phones) */
@media (max-width: 380px) {
  .hero h1 { font-size: 28px; }
  .price-card .amount { font-size: 38px; }
  .btn-primary, .btn-ghost { width: 100%; flex: none; }
}