:root {
  color-scheme: light;
  --ink: #12161c;
  --muted-ink: #5b6675;
  --soft-ink: #7c8796;
  --paper: #f7f8f7;
  --surface: #ffffff;
  --line: #dfe4e8;
  --dark: #0b1016;
  --teal: #0d7f7b;
  --teal-dark: #075e5c;
  --gold: #b9842c;
  --green: #5d7f3e;
  --shadow: 0 18px 50px rgba(18, 22, 28, 0.12);
  font-family:
    "Inter", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", Arial,
    sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
}

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

.site-header {
  position: fixed;
  z-index: 20;
  top: 0;
  left: 0;
  right: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 72px;
  padding: 14px clamp(20px, 5vw, 72px);
  color: #ffffff;
  background: rgba(7, 11, 16, 0.2);
  border-bottom: 1px solid rgba(255, 255, 255, 0.14);
  backdrop-filter: blur(16px);
  transition:
    background 180ms ease,
    color 180ms ease,
    border-color 180ms ease;
}

.site-header.is-scrolled,
.site-header.is-open {
  color: var(--ink);
  background: #ffffff;
  border-color: rgba(16, 24, 32, 0.1);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  flex: 0 0 auto;
  color: #ffffff;
  background: linear-gradient(135deg, var(--teal), var(--gold));
  border-radius: 8px;
  font-weight: 800;
  letter-spacing: 0;
}

.brand strong,
.brand small {
  display: block;
  line-height: 1.2;
}

.brand strong {
  font-size: 16px;
  letter-spacing: 0;
}

.brand small {
  margin-top: 2px;
  color: currentColor;
  font-size: 12px;
  opacity: 0.72;
}

.nav {
  display: flex;
  align-items: center;
  gap: clamp(18px, 3vw, 36px);
  font-size: 14px;
  font-weight: 600;
}

.nav a {
  opacity: 0.82;
}

.nav a:hover,
.nav a:focus-visible {
  opacity: 1;
}

.menu-toggle {
  display: none;
  width: 42px;
  height: 42px;
  padding: 0;
  color: currentColor;
  background: transparent;
  border: 1px solid currentColor;
  border-radius: 8px;
}

.menu-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  margin: 5px auto;
  background: currentColor;
  border-radius: 999px;
}

.hero {
  position: relative;
  display: grid;
  align-items: center;
  min-height: clamp(560px, 80vh, 780px);
  overflow: hidden;
  color: #ffffff;
  background: var(--dark);
}

.hero-media,
.hero-overlay {
  position: absolute;
  inset: 0;
}

.hero-media {
  background-image: image-set(
    url("assets/hero-ai-city.webp") type("image/webp"),
    url("assets/hero-ai-city.png") type("image/png")
  );
  background-position: center;
  background-size: cover;
  transform: scale(1.01);
}

.hero-overlay {
  background:
    linear-gradient(90deg, rgba(6, 9, 12, 0.92) 0%, rgba(6, 9, 12, 0.68) 43%, rgba(6, 9, 12, 0.22) 78%),
    linear-gradient(0deg, rgba(7, 11, 16, 0.74) 0%, rgba(7, 11, 16, 0) 42%);
}

.hero-content {
  position: relative;
  z-index: 1;
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
  padding: 112px 0 36px;
}

.eyebrow,
.section-kicker {
  margin: 0 0 14px;
  color: var(--gold);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 790px;
  margin: 0;
  font-size: clamp(40px, 6.2vw, 78px);
  line-height: 1.05;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 680px;
  margin: 24px 0 0;
  color: rgba(255, 255, 255, 0.78);
  font-size: clamp(17px, 2vw, 22px);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 46px;
  padding: 0 20px;
  border: 1px solid transparent;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 800;
  line-height: 1;
  transition:
    transform 160ms ease,
    border-color 160ms ease,
    background 160ms ease;
}

.button:hover,
.button:focus-visible {
  transform: translateY(-1px);
}

.button.primary {
  color: #ffffff;
  background: var(--teal);
  border-color: var(--teal);
}

.button.primary:hover,
.button.primary:focus-visible {
  background: var(--teal-dark);
  border-color: var(--teal-dark);
}

.button.secondary {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.34);
}

.hero-metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  max-width: 760px;
  margin: 36px 0 0;
}

.hero-metrics div {
  padding: 16px;
  background: rgba(255, 255, 255, 0.09);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 8px;
}

.hero-metrics dt {
  color: #ffffff;
  font-size: 20px;
  font-weight: 900;
  line-height: 1.2;
}

.hero-metrics dd {
  margin: 8px 0 0;
  color: rgba(255, 255, 255, 0.68);
  font-size: 14px;
}

.section {
  padding: clamp(72px, 10vw, 120px) 0;
  background: var(--surface);
}

.section.muted {
  background: var(--paper);
}

.section-inner {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
}

.intro {
  padding-top: clamp(52px, 7vw, 82px);
}

.intro-grid,
.approach-grid,
.contact-panel {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: clamp(28px, 6vw, 88px);
  align-items: start;
}

.intro h2,
.section-heading h2,
.contact h2 {
  margin: 0;
  font-size: clamp(30px, 4.4vw, 52px);
  line-height: 1.12;
  letter-spacing: 0;
}

.intro p:not(.section-kicker),
.contact p {
  margin: 4px 0 0;
  color: var(--muted-ink);
  font-size: 18px;
}

.section-heading {
  max-width: 650px;
  margin-bottom: 34px;
}

.service-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.service-card {
  min-height: 248px;
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 10px 30px rgba(18, 22, 28, 0.04);
}

.card-index {
  display: inline-block;
  margin-bottom: 28px;
  color: var(--teal);
  font-size: 13px;
  font-weight: 900;
}

.service-card h3,
.timeline h3,
.scenario-list h3 {
  margin: 0;
  font-size: 21px;
  line-height: 1.32;
}

.service-card p,
.timeline p,
.scenario-list p {
  margin: 12px 0 0;
  color: var(--muted-ink);
}

.sticky-heading {
  position: sticky;
  top: 110px;
  margin-bottom: 0;
}

.timeline {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.timeline li {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr);
  gap: 18px;
  padding: 26px 0;
  border-top: 1px solid var(--line);
}

.timeline li:last-child {
  border-bottom: 1px solid var(--line);
}

.timeline span {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  color: #ffffff;
  background: var(--ink);
  border-radius: 8px;
  font-size: 13px;
  font-weight: 900;
}

.scenario-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.scenario-list article {
  min-height: 220px;
  padding: 28px;
  background: var(--surface);
}

.contact {
  background: #111820;
  color: #ffffff;
}

.contact p {
  color: rgba(255, 255, 255, 0.68);
}

.contact-panel {
  align-items: stretch;
}

.contact-note {
  display: grid;
  align-content: center;
  gap: 14px;
  padding: 34px;
  background: #ffffff;
  color: var(--ink);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.contact-note strong {
  font-size: 24px;
  line-height: 1.24;
}

.contact-note span {
  color: var(--muted-ink);
}

.contact-note .button {
  justify-self: start;
  margin-top: 6px;
}

.site-footer {
  background: #0b1016;
  color: rgba(255, 255, 255, 0.72);
  font-size: 14px;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  width: min(1180px, calc(100% - 40px));
  min-height: 72px;
  margin: 0 auto;
}

.footer-inner a {
  color: rgba(255, 255, 255, 0.86);
}

@media (max-width: 920px) {
  .menu-toggle {
    display: block;
  }

  .nav {
    position: absolute;
    top: calc(100% + 1px);
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 10px 20px 18px;
    color: var(--ink);
    background: #ffffff;
    border-bottom: 1px solid rgba(16, 24, 32, 0.1);
  }

  .site-header.is-open .nav {
    display: flex;
  }

  .nav a {
    padding: 13px 0;
  }

  .hero {
    min-height: 84svh;
  }

  .hero-overlay {
    background:
      linear-gradient(90deg, rgba(6, 9, 12, 0.94) 0%, rgba(6, 9, 12, 0.76) 68%, rgba(6, 9, 12, 0.45) 100%),
      linear-gradient(0deg, rgba(7, 11, 16, 0.75) 0%, rgba(7, 11, 16, 0) 48%);
  }

  .hero-content {
    padding-top: 104px;
  }

  .hero-metrics,
  .service-grid,
  .scenario-list,
  .intro-grid,
  .approach-grid,
  .contact-panel {
    grid-template-columns: 1fr;
  }

  .sticky-heading {
    position: static;
  }
}

@media (max-width: 620px) {
  .site-header {
    min-height: 66px;
    padding: 12px 16px;
  }

  .brand small {
    display: none;
  }

  .hero {
    min-height: 82svh;
  }

  .hero-content,
  .section-inner,
  .footer-inner {
    width: min(100% - 32px, 1180px);
  }

  .hero h1 {
    font-size: 36px;
  }

  .hero-copy {
    font-size: 17px;
  }

  .hero-metrics {
    gap: 10px;
    margin-top: 36px;
  }

  .hero-metrics div {
    padding: 14px;
  }

  .button {
    width: 100%;
  }

  .service-card,
  .scenario-list article,
  .contact-note {
    padding: 22px;
  }

  .timeline li {
    grid-template-columns: 48px minmax(0, 1fr);
    gap: 14px;
  }

  .timeline span {
    width: 40px;
    height: 40px;
  }

  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    padding: 18px 0;
  }
}