:root {
  --bg: #f3f6fb;
  --bg-deep: #0b1f3a;
  --ink: #142033;
  --muted: #5c6b80;
  --line: #d7e0ec;
  --brand: #2f6fed;
  --brand-2: #1e54c8;
  --card: #ffffff;
  --font: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --display: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background:
    radial-gradient(1200px 600px at 12% -10%, rgba(47, 111, 237, 0.16), transparent 60%),
    radial-gradient(900px 500px at 90% 0%, rgba(30, 84, 200, 0.12), transparent 55%),
    linear-gradient(180deg, #eef3fa 0%, var(--bg) 42%, #e8eef7 100%);
  line-height: 1.65;
}
a {
  color: inherit;
  text-decoration: underline;
  text-underline-offset: 0.18em;
}
.nav-brand,
.btn { text-decoration: none; }
img { max-width: 100%; display: block; }

.nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 6vw;
  background: rgba(243, 246, 251, 0.86);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(215, 224, 236, 0.9);
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--display);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: 0.04em;
}
.nav-logo-img {
  height: 64px;
  width: 64px;
  display: block;
  object-fit: contain;
}
.nav-links {
  display: flex;
  flex-wrap: nowrap;
  justify-content: flex-end;
  align-items: center;
  gap: 22px;
  font-size: 14px;
  color: var(--muted);
  white-space: nowrap;
}
.nav-links a:hover { color: var(--brand); }

.hero {
  min-height: calc(100vh - 65px);
  display: grid;
  align-content: center;
  padding: 64px 6vw 72px;
  max-width: 1100px;
}
.eyebrow {
  margin: 0 0 14px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.12em;
}
.hero h1 {
  margin: 0;
  font-family: var(--display);
  font-size: clamp(40px, 7vw, 64px);
  line-height: 1.08;
  letter-spacing: 0.02em;
}
.hero-sub {
  margin: 18px 0 0;
  max-width: 34em;
  font-size: clamp(16px, 2.2vw, 19px);
  color: var(--muted);
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
}
.btn-primary {
  color: #fff;
  background: linear-gradient(145deg, var(--brand), var(--brand-2));
  box-shadow: 0 10px 24px rgba(47, 111, 237, 0.28);
}
.btn-ghost {
  color: var(--ink);
  background: rgba(255, 255, 255, 0.7);
  border-color: var(--line);
}

.section {
  padding: 72px 6vw;
}
.section-inner {
  max-width: 1100px;
  margin: 0 auto;
}
.section h2 {
  margin: 0 0 10px;
  font-family: var(--display);
  font-size: clamp(26px, 4vw, 34px);
}
.section .lead {
  margin: 0;
  max-width: 40em;
  color: var(--muted);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: 28px;
}
.feature {
  padding: 22px 20px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
}
.feature h3 {
  margin: 0 0 8px;
  font-size: 18px;
}
.feature p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.about-box {
  margin-top: 22px;
  padding: 24px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
}
.about-box p { margin: 0 0 12px; color: var(--muted); }
.about-box p:last-child { margin-bottom: 0; }
.about-box strong { color: var(--ink); font-weight: 600; }

.footer {
  padding: 36px 6vw 48px;
  background: var(--bg-deep);
  color: rgba(255, 255, 255, 0.82);
}
.footer-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 18px 32px;
}
.footer a { color: #9ec0ff; }
.footer a:hover { color: #fff; }
.footer .muted { color: rgba(255, 255, 255, 0.55); font-size: 13px; }
.footer-entry {
  min-width: 220px;
}
.footer-entry strong {
  display: block;
  margin-bottom: 6px;
  color: #fff;
  font-size: 15px;
}
.footer-entry p {
  margin: 0;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.7);
}

.privacy-page {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 6vw 80px;
}
.privacy-page h1 {
  margin: 0 0 8px;
  font-family: var(--display);
  font-size: 32px;
}
.privacy-page .meta {
  margin: 0 0 28px;
  color: var(--muted);
  font-size: 14px;
}
.privacy-page h2 {
  margin: 28px 0 10px;
  font-size: 18px;
}
.privacy-page p, .privacy-page li {
  color: var(--muted);
  font-size: 15px;
}
.privacy-page ul { padding-left: 1.2em; }

.download-page {
  max-width: 1100px;
  margin: 0 auto;
  padding: 48px 6vw 80px;
}
.download-page h1 {
  margin: 0 0 8px;
  font-family: var(--display);
  font-size: clamp(28px, 5vw, 36px);
}
.download-page .lead {
  margin: 0;
  max-width: 40em;
  color: var(--muted);
}
.download-tip {
  margin-top: 18px;
  padding: 12px 14px;
  border-radius: 10px;
  background: #fff7e8;
  border: 1px solid #f0d7a2;
  color: #7a4e00;
  font-size: 14px;
}
.download-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 28px;
}
.download-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  padding: 24px 22px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
}
.download-logo {
  width: 72px;
  height: 72px;
  object-fit: contain;
}
.download-card h2 {
  margin: 4px 0 0;
  font-size: 22px;
}
.download-card p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}
.download-meta {
  font-size: 13px;
}
.download-card .btn {
  margin-top: 10px;
}

@media (max-width: 800px) {
  .nav {
    flex-wrap: nowrap;
    gap: 8px;
    padding: 8px 14px;
  }
  .nav-logo-img {
    width: 44px;
    height: 44px;
  }
  .nav-links {
    flex: 1 1 auto;
    justify-content: flex-end;
    gap: 12px;
    font-size: 14px;
  }
  .feature-grid,
  .download-grid { grid-template-columns: 1fr; }
  .hero { min-height: auto; padding-top: 48px; }
  .download-page { padding-top: 28px; }
  .download-card .btn { width: 100%; }
}
@media (max-width: 380px) {
  .nav { padding: 8px 12px; }
  .nav-logo-img {
    width: 40px;
    height: 40px;
  }
  .nav-links {
    gap: 8px;
    font-size: 13px;
  }
}