:root {
  --navy: #07151d;
  --navy-2: #0d2631;
  --steel: #477384;
  --paper: #f2efe7;
  --white: #fffdf8;
  --copper: #d56c35;
  --graphite: #1a2328;
  --ink: #10191d;
  --line: rgba(16, 25, 29, .2);
  --max: 1280px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: Inter, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
}
img { display: block; width: 100%; }
a { color: inherit; text-decoration: none; }
button, input, textarea { font: inherit; }
.sr-only, .skip-link {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}
.skip-link:focus {
  width: auto;
  height: auto;
  clip: auto;
  top: 10px;
  left: 10px;
  z-index: 1000;
  margin: 0;
  padding: 10px 14px;
  background: var(--paper);
}

.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 100;
  height: 78px;
  padding: 0 clamp(22px, 4vw, 70px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--white);
  transition: background .3s ease, color .3s ease, border-color .3s ease;
  border-bottom: 1px solid transparent;
}
.site-header.is-scrolled {
  color: var(--ink);
  background: rgba(242, 239, 231, .94);
  border-color: rgba(16, 25, 29, .15);
  backdrop-filter: blur(12px);
}
.brand { display: inline-flex; align-items: center; gap: 12px; }
.brand-mark { width: 43px; height: 43px; flex: 0 0 auto; }
.brand span { display: grid; gap: 2px; }
.brand strong { font-size: 16px; letter-spacing: .12em; }
.brand small { font-size: 8px; letter-spacing: .22em; opacity: .65; }
.site-nav { display: flex; align-items: center; gap: clamp(18px, 2.2vw, 38px); }
.site-nav a { font-size: 13px; letter-spacing: .05em; }
.site-nav a:not(.nav-contact) { opacity: .78; }
.site-nav a:hover { opacity: 1; }
.nav-contact { border-bottom: 1px solid currentColor; padding: 8px 0; }
.menu-toggle { display: none; }

.hero {
  position: relative;
  min-height: 100svh;
  overflow: hidden;
  color: var(--white);
  background: var(--navy);
}
.hero-image, .hero-shade { position: absolute; inset: 0; height: 100%; }
.hero-image { object-fit: cover; object-position: center; }
.hero-shade {
  background:
    linear-gradient(90deg, rgba(4, 15, 22, .95) 0%, rgba(4, 15, 22, .72) 35%, rgba(4, 15, 22, .08) 72%),
    linear-gradient(0deg, rgba(4, 15, 22, .68) 0%, transparent 42%);
}
.hero-content {
  position: relative;
  z-index: 3;
  width: min(760px, 82vw);
  padding: clamp(150px, 20vh, 230px) 0 120px clamp(24px, 7vw, 120px);
}
.eyebrow, .section-index {
  margin: 0 0 28px;
  font-size: 12px;
  line-height: 1.4;
  letter-spacing: .22em;
  text-transform: uppercase;
}
.eyebrow { color: #b8ccd3; }
.hero h1, .section-head h2, .structure h2, .validation h2, .development h2, .about h2, .contact h2 {
  margin: 0;
  font-family: Georgia, "Times New Roman", "Songti SC", serif;
  font-weight: 400;
  letter-spacing: -.05em;
}
.hero h1 { font-size: clamp(56px, 8vw, 132px); line-height: .91; }
.hero h1 em { color: #d9e5e8; font-weight: 400; }
.hero-copy { max-width: 570px; margin: 40px 0 32px; color: #c4d2d6; font-size: clamp(16px, 1.4vw, 20px); line-height: 1.8; }
.text-link { display: inline-flex; gap: 36px; align-items: center; padding-bottom: 10px; border-bottom: 1px solid rgba(255,255,255,.5); font-size: 14px; }
.text-link span { color: var(--copper); font-size: 20px; }
.hero-record {
  position: absolute;
  z-index: 4;
  left: clamp(24px, 7vw, 120px);
  right: clamp(24px, 7vw, 120px);
  bottom: 34px;
  display: flex;
  justify-content: flex-end;
  gap: clamp(30px, 5vw, 76px);
}
.hero-record div { display: grid; gap: 4px; min-width: 90px; }
.hero-record strong { font: 400 22px/1 Georgia, serif; }
.hero-record span { color: #9eb1b8; font-size: 10px; letter-spacing: .16em; }
.hero-orbit { position: absolute; z-index: 2; border: 1px solid rgba(255,255,255,.18); border-radius: 50%; pointer-events: none; }
.orbit-a { width: 56vw; aspect-ratio: 1; right: -12vw; top: -18vw; }
.orbit-b { width: 44vw; aspect-ratio: 1; right: -6vw; top: -12vw; border-color: rgba(213,108,53,.42); }

.section-light { background: var(--paper); }
.section-dark { background: var(--navy); color: var(--white); }
.routes { padding: clamp(90px, 12vw, 180px) 0; overflow: hidden; }
.section-head {
  max-width: var(--max);
  margin: 0 auto clamp(90px, 12vw, 170px);
  padding: 0 clamp(24px, 6vw, 96px);
  display: grid;
  grid-template-columns: .55fr 1.3fr .8fr;
  gap: 40px;
  align-items: end;
}
.section-index { color: var(--copper); }
.section-head h2, .structure h2, .development h2, .about h2, .contact h2 { font-size: clamp(48px, 6.5vw, 98px); line-height: .95; }
.section-head > p:last-child { margin: 0; font-size: 16px; line-height: 1.9; color: #536269; }
.route {
  max-width: 1440px;
  margin: 0 auto clamp(100px, 12vw, 180px);
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(300px, .6fr);
  align-items: center;
}
.route:last-child { margin-bottom: 0; }
.route figure { margin: 0; position: relative; overflow: hidden; min-height: 560px; }
.route figure::after { content: ""; position: absolute; inset: 0; border: 1px solid rgba(255,255,255,.15); }
.route img { height: 100%; min-height: 560px; object-fit: cover; transition: transform .7s ease; }
.route:hover img { transform: scale(1.02); }
.route-copy { padding: clamp(44px, 6vw, 92px); position: relative; }
.route-copy::before { content: ""; position: absolute; left: 0; top: 0; width: 1px; height: 100%; background: var(--line); }
.route-copy span { font: 12px/1.4 "Courier New", monospace; color: var(--copper); letter-spacing: .12em; }
.route-copy h3 { margin: 24px 0 32px; font: 400 clamp(42px, 5vw, 74px)/1 Georgia, serif; letter-spacing: -.04em; }
.route-copy p { margin: 0; max-width: 440px; color: #526269; line-height: 1.9; }
.route-right { grid-template-columns: minmax(300px, .6fr) minmax(0, 1.4fr); }
.route-right figure { grid-column: 2; }
.route-right .route-copy { grid-column: 1; grid-row: 1; }
.route-right .route-copy::before { left: auto; right: 0; }

.structure { padding: clamp(100px, 14vw, 200px) 0 0; overflow: hidden; }
.structure-intro { max-width: var(--max); margin: 0 auto 90px; padding: 0 clamp(24px, 6vw, 96px); display: grid; grid-template-columns: .55fr 1.45fr; }
.structure-intro .section-index { grid-column: 1; }
.structure-intro h2 { grid-column: 2; }
.winding-band { position: relative; min-height: 650px; display: grid; grid-template-columns: 1.3fr .7fr; background: #091c25; }
.winding-band img { height: 100%; min-height: 650px; object-fit: cover; }
.winding-copy { display: flex; flex-direction: column; justify-content: flex-end; padding: clamp(48px, 7vw, 110px); border-left: 1px solid rgba(255,255,255,.12); }
.winding-copy p { margin: 0 0 20px; color: #8fb1bd; font-size: 11px; letter-spacing: .18em; }
.winding-copy h3 { margin: 0; max-width: 430px; font: 400 clamp(34px, 4vw, 60px)/1.1 Georgia, serif; }
.structure-sequence {
  position: relative;
  max-width: var(--max);
  margin: 0 auto;
  padding: 100px clamp(24px, 6vw, 96px);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 42px;
}
.sequence-line { position: absolute; top: 122px; left: 8%; right: 8%; height: 1px; background: rgba(255,255,255,.2); }
.structure-sequence div:not(.sequence-line) { position: relative; padding-top: 54px; }
.structure-sequence div:not(.sequence-line)::before { content: ""; position: absolute; top: 17px; width: 11px; height: 11px; border: 2px solid var(--copper); border-radius: 50%; background: var(--navy); }
.structure-sequence strong, .structure-sequence span { display: block; }
.structure-sequence strong { margin-bottom: 12px; font: 400 25px/1 Georgia, serif; }
.structure-sequence span { color: #92a8af; font-size: 13px; line-height: 1.7; }
.assembly-figure { margin: 0; display: grid; grid-template-columns: 1.5fr .5fr; min-height: 700px; }
.assembly-figure img { height: 100%; min-height: 700px; object-fit: cover; }
.assembly-figure figcaption { padding: clamp(45px, 6vw, 90px); background: var(--paper); color: var(--ink); display: flex; flex-direction: column; justify-content: flex-end; }
.assembly-figure figcaption span { color: var(--copper); font-size: 12px; letter-spacing: .18em; }
.assembly-figure figcaption strong { margin-top: 22px; font: 400 clamp(28px, 3vw, 44px)/1.35 Georgia, serif; }

.validation { position: relative; min-height: 1050px; color: var(--white); background: #07131a; overflow: hidden; }
.validation-image, .validation-shade { position: absolute; inset: 0; height: 100%; }
.validation-image { object-fit: cover; }
.validation-shade { background: linear-gradient(90deg, rgba(5,17,24,.92) 0%, rgba(5,17,24,.65) 42%, rgba(5,17,24,.08) 78%); }
.validation-copy { position: relative; z-index: 2; min-height: 1050px; max-width: var(--max); margin: 0 auto; padding: clamp(110px, 13vw, 190px) clamp(24px, 6vw, 96px); display: flex; flex-direction: column; align-items: flex-start; }
.validation h2 { font-size: clamp(64px, 9vw, 138px); line-height: .83; }
.validation h2 span { color: var(--copper); font-style: italic; }
.validation-copy > p:not(.section-index) { max-width: 520px; margin: 50px 0 0; color: #c1d0d4; font-size: 17px; line-height: 1.9; }
.validation-note { margin-top: auto; padding-top: 30px; border-top: 1px solid rgba(255,255,255,.3); max-width: 480px; display: grid; grid-template-columns: 110px 1fr; gap: 32px; }
.validation-note span { color: #8fb1bd; font-size: 11px; letter-spacing: .16em; }
.validation-note strong { font-size: 15px; line-height: 1.8; }

.development { display: grid; grid-template-columns: 1.05fr .95fr; min-height: 920px; }
.development-visual { overflow: hidden; }
.development-visual img { height: 100%; object-fit: cover; }
.development-content { padding: clamp(90px, 10vw, 150px) clamp(40px, 8vw, 120px); display: flex; flex-direction: column; }
.development h2 { font-size: clamp(50px, 6vw, 88px); }
.timeline { margin-top: auto; }
.timeline > div { display: grid; grid-template-columns: 100px 1fr; gap: 34px; padding: 26px 0; border-top: 1px solid var(--line); }
.timeline time { color: var(--copper); font: 16px/1 "Courier New", monospace; }
.timeline p { margin: 0; display: grid; gap: 8px; }
.timeline strong { font: 400 22px/1.2 Georgia, serif; }
.timeline span { color: #68767b; font-size: 13px; line-height: 1.65; }

.about { min-height: 900px; padding: clamp(100px, 12vw, 180px) clamp(24px, 7vw, 120px); display: grid; grid-template-columns: 1fr 1fr; align-items: center; overflow: hidden; }
.about-ring { position: relative; width: min(44vw, 620px); aspect-ratio: 1; border: clamp(25px, 4vw, 58px) solid #162d37; border-radius: 50%; box-shadow: inset 0 0 0 2px #597987, 0 0 0 2px #274550; }
.about-ring::before { content: ""; position: absolute; inset: 14%; border: 2px solid rgba(213,108,53,.65); border-radius: 50%; }
.about-ring span { position: absolute; width: 30%; height: 3px; background: var(--copper); top: 50%; left: 35%; transform: rotate(-28deg); }
.about-copy { max-width: 650px; }
.about-copy > p:not(.section-index) { margin: 44px 0; color: #a6bbc2; line-height: 1.95; font-size: 16px; }
.about dl { margin: 0; }
.about dl div { display: grid; grid-template-columns: 120px 1fr; gap: 30px; padding: 19px 0; border-top: 1px solid rgba(255,255,255,.16); }
.about dt { color: #77939d; font-size: 12px; }
.about dd { margin: 0; font-size: 14px; }

.contact { padding: clamp(100px, 12vw, 180px) clamp(24px, 7vw, 120px); display: grid; grid-template-columns: .85fr 1.15fr; gap: clamp(70px, 10vw, 160px); }
.contact-lead > p:not(.section-index) { max-width: 520px; color: #637177; line-height: 1.9; }
.inquiry-form { align-self: end; display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.inquiry-form label { display: grid; gap: 10px; }
.inquiry-form label span { color: #66757a; font-size: 12px; letter-spacing: .08em; }
.inquiry-form input, .inquiry-form textarea { width: 100%; border: 0; border-bottom: 1px solid #90999b; border-radius: 0; background: transparent; color: var(--ink); padding: 12px 0; outline: none; resize: vertical; }
.inquiry-form input:focus, .inquiry-form textarea:focus { border-color: var(--copper); }
.field-wide { grid-column: 1 / -1; }
.inquiry-form button { grid-column: 1 / -1; margin-top: 14px; border: 0; border-top: 1px solid var(--ink); border-bottom: 1px solid var(--ink); background: transparent; padding: 20px 0; display: flex; justify-content: space-between; cursor: pointer; text-align: left; }
.inquiry-form button span { color: var(--copper); font-size: 20px; }
.form-result { grid-column: 1 / -1; min-height: 24px; margin: 0; color: #8b431f; font-size: 13px; line-height: 1.7; }

.site-footer { min-height: 220px; padding: 60px clamp(24px, 7vw, 120px); background: #041016; color: var(--white); display: grid; grid-template-columns: 1fr 1fr auto; gap: 50px; align-items: end; }
.footer-meta p { margin: 8px 0; color: #80979f; font-size: 11px; letter-spacing: .08em; }
.back-top { font-size: 12px; border-bottom: 1px solid rgba(255,255,255,.5); padding-bottom: 7px; }

@media (max-width: 1024px) {
  .site-nav { gap: 18px; }
  .site-nav a { font-size: 12px; }
  .section-head { grid-template-columns: 1fr 1.5fr; }
  .section-head > p:last-child { grid-column: 2; }
  .route, .route-right { grid-template-columns: 1.25fr .75fr; }
  .route-right figure { grid-column: 2; }
  .route figure, .route img { min-height: 470px; }
  .winding-band { grid-template-columns: 1fr 1fr; }
  .development { grid-template-columns: 1fr; }
  .development-visual { min-height: 620px; }
  .development-content { min-height: 760px; }
  .about { grid-template-columns: .8fr 1.2fr; gap: 60px; }
  .contact { grid-template-columns: 1fr; }
}

@media (max-width: 760px) {
  .site-header { height: 68px; padding: 0 20px; }
  .brand-mark { width: 36px; height: 36px; }
  .brand strong { font-size: 14px; }
  .menu-toggle { display: grid; gap: 6px; width: 42px; height: 42px; padding: 12px 8px; border: 0; background: transparent; color: currentColor; z-index: 102; }
  .menu-toggle span:not(.sr-only) { display: block; height: 1px; background: currentColor; transition: transform .25s ease; }
  .site-header.menu-open .menu-toggle span:first-child { transform: translateY(3.5px) rotate(45deg); }
  .site-header.menu-open .menu-toggle span:nth-child(2) { transform: translateY(-3.5px) rotate(-45deg); }
  .site-nav { position: fixed; inset: 0; padding: 110px 28px 40px; display: none; flex-direction: column; align-items: stretch; justify-content: flex-start; gap: 0; background: var(--paper); color: var(--ink); }
  .site-header.menu-open .site-nav { display: flex; }
  .site-nav a { padding: 18px 0; font: 400 28px/1.1 Georgia, serif; border-bottom: 1px solid var(--line); }
  .nav-contact { margin-top: 20px; color: var(--copper); }

  .hero { min-height: 920px; }
  .hero-image { object-position: 61% center; }
  .hero-shade { background: linear-gradient(0deg, rgba(4,15,22,.96) 0%, rgba(4,15,22,.76) 55%, rgba(4,15,22,.14) 100%); }
  .hero-content { width: auto; padding: 145px 24px 250px; }
  .hero h1 { font-size: clamp(54px, 17vw, 74px); }
  .hero-copy { font-size: 15px; line-height: 1.75; }
  .hero-record { left: 24px; right: 24px; justify-content: space-between; gap: 12px; }
  .hero-record div { min-width: 0; }
  .hero-record strong { font-size: 18px; }
  .orbit-a { width: 110vw; right: -56vw; top: -10vw; }
  .orbit-b { width: 86vw; right: -40vw; top: 3vw; }

  .section-head { display: block; margin-bottom: 70px; }
  .section-head h2, .structure h2, .development h2, .about h2, .contact h2 { font-size: clamp(45px, 13vw, 62px); }
  .section-head > p:last-child { margin-top: 32px; font-size: 14px; }
  .route, .route-right { display: flex; flex-direction: column; margin-bottom: 90px; }
  .route figure, .route-right figure { width: 100%; min-height: 350px; order: 1; }
  .route img { min-height: 350px; }
  .route-copy, .route-right .route-copy { order: 2; width: 100%; padding: 38px 24px 0; }
  .route-copy::before { display: none; }
  .route-copy h3 { font-size: 47px; }

  .structure-intro { display: block; margin-bottom: 60px; }
  .winding-band { display: block; min-height: 0; }
  .winding-band img { min-height: 430px; }
  .winding-copy { min-height: 360px; border-left: 0; border-top: 1px solid rgba(255,255,255,.12); }
  .structure-sequence { grid-template-columns: 1fr 1fr; padding-top: 60px; }
  .sequence-line { display: none; }
  .structure-sequence div:not(.sequence-line) { padding-top: 34px; border-top: 1px solid rgba(255,255,255,.18); }
  .structure-sequence div:not(.sequence-line)::before { top: -7px; }
  .assembly-figure { display: block; min-height: 0; }
  .assembly-figure img { min-height: 430px; }
  .assembly-figure figcaption { min-height: 300px; }

  .validation, .validation-copy { min-height: 900px; }
  .validation-image { object-position: 62% center; }
  .validation-shade { background: linear-gradient(0deg, rgba(5,17,24,.96) 0%, rgba(5,17,24,.7) 60%, rgba(5,17,24,.18) 100%); }
  .validation h2 { font-size: clamp(61px, 17vw, 82px); }
  .validation-copy > p:not(.section-index) { font-size: 15px; }

  .development-visual { min-height: 430px; }
  .development-content { min-height: 720px; padding-left: 24px; padding-right: 24px; }
  .timeline > div { grid-template-columns: 72px 1fr; gap: 18px; }
  .about { display: block; padding-left: 24px; padding-right: 24px; }
  .about-ring { width: 76vw; margin: 0 auto 80px; }
  .about dl div { grid-template-columns: 90px 1fr; gap: 18px; }
  .contact { padding-left: 24px; padding-right: 24px; }
  .inquiry-form { grid-template-columns: 1fr; }
  .field-wide, .inquiry-form button, .form-result { grid-column: 1; }
  .site-footer { grid-template-columns: 1fr; gap: 34px; align-items: start; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}