:root {
  --bg: #0b1220;
  --bg-soft: #111a2b;
  --surface: #162235;
  --border: rgba(255, 255, 255, 0.08);
  --text: #f2f5fa;
  --text-2: rgba(242, 245, 250, 0.72);
  --text-3: rgba(242, 245, 250, 0.45);
  --brand: #3de0ff;
  --brand-2: #4aa3ff;
  --solo: #8b9bff;
  --wifi: #3aa0ff;
  --battery: #2fd48a;
  --fanqie: #ff6b5b;
  --wrap: 1080px;
  --radius: 16px;
  --font: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
}

body.menu-open { overflow: hidden; }

img { display: block; max-width: 100%; }

a { color: inherit; text-decoration: none; }

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

.wrap {
  width: min(var(--wrap), calc(100% - 48px));
  margin: 0 auto;
}

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(11, 18, 32, 0.85);
  border-bottom: 1px solid transparent;
  backdrop-filter: blur(16px);
  transition: border-color 0.2s, background 0.2s;
}

.site-header.is-scrolled {
  border-bottom-color: var(--border);
  background: rgba(11, 18, 32, 0.94);
}

.header-row {
  display: flex;
  align-items: center;
  gap: 24px;
  min-height: 64px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 16px;
}

.brand img {
  width: 32px;
  height: 32px;
  border-radius: 8px;
}

.nav-main {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

.nav-main a {
  padding: 8px 14px;
  border-radius: 8px;
  color: var(--text-2);
  font-size: 14px;
  font-weight: 500;
  transition: color 0.15s, background 0.15s;
}

.nav-main a:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.05);
}

.header-cta { margin-left: 8px; }

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  margin-left: auto;
  place-items: center;
  gap: 5px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.05);
}

.nav-toggle span {
  display: block;
  width: 16px;
  height: 2px;
  border-radius: 2px;
  background: var(--text);
  transition: transform 0.2s var(--ease);
}

body.menu-open .nav-toggle span:first-child {
  transform: translateY(3.5px) rotate(45deg);
}

body.menu-open .nav-toggle span:last-child {
  transform: translateY(-3.5px) rotate(-45deg);
}

.mobile-scrim,
.mobile-nav {
  display: none;
}

.mobile-scrim.is-open,
body.menu-open .mobile-scrim {
  display: block;
  position: fixed;
  inset: 0;
  z-index: 90;
  background: rgba(0, 0, 0, 0.5);
}

.mobile-nav.is-open,
body.menu-open .mobile-nav {
  display: grid;
  position: fixed;
  top: 72px;
  left: 16px;
  right: 16px;
  z-index: 95;
  gap: 2px;
  padding: 12px;
  border-radius: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.4);
}

.mobile-nav[hidden],
.mobile-scrim[hidden] {
  display: none !important;
}

.mobile-nav a {
  padding: 14px 12px;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 500;
}

.mobile-nav a:hover {
  background: rgba(255, 255, 255, 0.05);
}

.mobile-nav hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 6px 0;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 22px;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 600;
  transition: transform 0.15s, background 0.15s, border-color 0.15s, opacity 0.15s;
}

.btn:hover { transform: translateY(-1px); }

.btn-sm {
  min-height: 36px;
  padding: 0 14px;
  font-size: 13px;
  border-radius: 10px;
}

.btn-primary {
  background: linear-gradient(135deg, #5ee7ff, #3aa0ff);
  color: #061018;
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--border);
  color: var(--text);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.16);
}

/* ===== Hero ===== */
.hero {
  padding: 88px 0 72px;
  background:
    radial-gradient(ellipse 70% 55% at 50% -10%, rgba(58, 160, 255, 0.18), transparent 60%),
    radial-gradient(ellipse 40% 40% at 90% 40%, rgba(47, 212, 138, 0.08), transparent 55%),
    var(--bg);
}

.hero-inner {
  max-width: 720px;
  text-align: center;
  margin: 0 auto;
}

.eyebrow {
  margin: 0 0 16px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.06em;
}

.hero h1 {
  margin: 0;
  font-size: clamp(36px, 5.5vw, 56px);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.lead {
  margin: 20px auto 0;
  max-width: 42em;
  color: var(--text-2);
  font-size: 16px;
  line-height: 1.85;
}

.lead strong {
  color: var(--text);
  font-weight: 650;
}

.hero-actions {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
}

/* ===== Section head ===== */
.section-head {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 40px;
}

.section-head h2 {
  margin: 0;
  font-size: clamp(26px, 3.2vw, 34px);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.section-head p {
  margin: 12px 0 0;
  color: var(--text-2);
  font-size: 15px;
  line-height: 1.7;
}

/* ===== Products / 4 apps ===== */
.products {
  padding: 24px 0 88px;
}

.app-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.app-card {
  display: flex;
  flex-direction: column;
  padding: 24px 22px;
  border-radius: var(--radius);
  background: var(--surface);
  border: 1px solid var(--border);
  transition: border-color 0.2s, transform 0.2s var(--ease), box-shadow 0.2s;
  min-height: 280px;
}

.app-card:hover {
  transform: translateY(-3px);
  border-color: rgba(255, 255, 255, 0.16);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.28);
}

.app-card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 18px;
}

.app-icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
}

.app-tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  color: var(--solo);
  background: rgba(139, 155, 255, 0.12);
}

.tag-wifi {
  color: var(--wifi);
  background: rgba(58, 160, 255, 0.12);
}

.tag-battery {
  color: var(--battery);
  background: rgba(47, 212, 138, 0.12);
}

.tag-fanqie {
  color: var(--fanqie);
  background: rgba(255, 107, 91, 0.12);
}

.app-card h3 {
  margin: 0;
  font-size: 18px;
  font-weight: 650;
}

.app-card p {
  margin: 10px 0 0;
  color: var(--text-2);
  font-size: 14px;
  line-height: 1.65;
  flex: 1;
}

.app-link {
  margin-top: 20px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 600;
}

.app-card:hover .app-link {
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ===== Promise ===== */
.promise {
  padding: 24px 0 80px;
}

.promise-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.promise-grid article {
  padding: 24px 22px;
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
}

.promise-grid h3 {
  margin: 0;
  font-size: 17px;
  font-weight: 650;
}

.promise-grid p {
  margin: 10px 0 0;
  color: var(--text-2);
  font-size: 14px;
  line-height: 1.75;
}

/* ===== Vision ===== */
.vision {
  padding: 72px 0;
  background: var(--bg-soft);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.vision-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.vision-grid article {
  padding: 22px 20px;
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
}

.vision-grid span {
  display: block;
  margin-bottom: 14px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.vision-grid h3 {
  margin: 0;
  font-size: 17px;
  font-weight: 650;
}

.vision-grid p {
  margin: 8px 0 0;
  color: var(--text-2);
  font-size: 13px;
  line-height: 1.65;
}

/* ===== About ===== */
.about {
  padding: 88px 0;
}

.about-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 48px;
  align-items: start;
}

.about h2 {
  margin: 0;
  font-size: clamp(26px, 3.2vw, 34px);
  font-weight: 700;
}

.about p {
  margin: 16px 0 0;
  color: var(--text-2);
  font-size: 15px;
  line-height: 1.8;
}

.about-meta {
  margin: 0;
  display: grid;
  gap: 0;
}

.about-meta > div {
  display: grid;
  gap: 4px;
  padding: 16px 0;
  border-top: 1px solid var(--border);
}

.about-meta > div:last-child {
  border-bottom: 1px solid var(--border);
}

.about-meta dt {
  color: var(--text-3);
  font-size: 12px;
  font-weight: 500;
}

.about-meta dd {
  margin: 0;
  font-size: 14px;
  font-weight: 500;
}

/* ===== Footer ===== */
.site-footer {
  padding: 36px 0 48px;
  border-top: 1px solid var(--border);
  background: #080e18;
}

.footer-grid {
  display: grid;
  gap: 24px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-brand img { border-radius: 7px; }

.footer-brand strong {
  display: block;
  font-size: 14px;
}

.footer-brand span {
  color: var(--text-3);
  font-size: 12px;
}

.footer-apps {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
}

.footer-apps a {
  color: var(--text-2);
  font-size: 13px;
}

.footer-apps a:hover { color: var(--text); }

.footer-legal {
  color: var(--text-3);
  font-size: 12px;
  line-height: 1.7;
}

.footer-legal a { color: inherit; }

/* ===== Responsive ===== */
@media (max-width: 960px) {
  .nav-main,
  .header-cta {
    display: none;
  }

  .nav-toggle {
    display: grid;
  }

  .app-grid {
    grid-template-columns: 1fr 1fr;
  }

  .promise-grid {
    grid-template-columns: 1fr;
  }

  .vision-grid {
    grid-template-columns: 1fr 1fr;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }
}

@media (max-width: 560px) {
  .wrap {
    width: calc(100% - 32px);
  }

  .hero {
    padding: 56px 0 48px;
  }

  .lead {
    font-size: 15px;
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .app-grid {
    grid-template-columns: 1fr;
  }

  .app-card {
    min-height: 0;
  }

  .vision-grid {
    grid-template-columns: 1fr;
  }

  .products {
    padding-bottom: 64px;
  }

  .vision,
  .about {
    padding: 56px 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .app-card,
  .btn {
    transition: none;
  }
}