:root {
  --bg: #050a12;
  --bg-soft: #09111d;
  --panel: #0d1724;
  --line: rgba(186, 218, 236, .18);
  --text: #eef6fb;
  --muted: #99aab8;
  --cyan: #57c9ef;
  --amber: #ffb44a;
  --amber-soft: #ffd18a;
  --max: 1240px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; background: var(--bg); }
body {
  margin: 0;
  color: var(--text);
  background: var(--bg);
  font-family: "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", system-ui, sans-serif;
  line-height: 1.85;
  font-size: 16px;
  overflow-x: hidden;
}
a { color: inherit; }
button { font: inherit; }
.sr-only { 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 { position: fixed; z-index: 1000; top: 8px; left: 8px; padding: 10px 16px; color: #06101a; background: var(--amber); transform: translateY(-150%); }
.skip-link:focus { transform: translateY(0); }

.scroll-progress { position: fixed; inset: 0 0 auto; height: 2px; z-index: 100; background: transparent; }
.scroll-progress span { display: block; width: 0; height: 100%; background: var(--amber); box-shadow: 0 0 14px var(--amber); }

.site-header {
  position: fixed; z-index: 90; top: 0; left: 0; right: 0;
  display: flex; align-items: center; justify-content: space-between;
  padding: 22px 4vw; transition: background .3s, padding .3s, border-color .3s;
  border-bottom: 1px solid transparent;
}
.site-header.scrolled { padding-top: 13px; padding-bottom: 13px; background: rgba(5,10,18,.9); border-color: var(--line); backdrop-filter: blur(14px); }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; line-height: 1.05; letter-spacing: .1em; }
.brand-mark { width: 31px; height: 31px; border: 2px solid var(--cyan); border-radius: 50%; position: relative; box-shadow: inset -8px 0 0 rgba(87,201,239,.14); }
.brand-mark::after { content: ""; position: absolute; width: 40px; height: 9px; border-top: 2px solid var(--amber); transform: rotate(-15deg); top: 12px; left: -6px; }
.brand b { display: block; font-size: .78rem; }
.brand small { color: var(--muted); font-size: .58rem; }
.site-nav { display: flex; gap: clamp(20px, 3vw, 46px); }
.site-nav a { color: #cad9e3; text-decoration: none; font: 700 .72rem/1 system-ui, sans-serif; letter-spacing: .18em; transition: color .2s; }
.site-nav a:hover, .site-nav a:focus-visible { color: var(--amber); }
.nav-toggle { display: none; width: 42px; height: 42px; border: 1px solid var(--line); background: rgba(5,10,18,.72); color: var(--text); padding: 11px; }
.nav-toggle > span:not(.sr-only) { display: block; height: 1px; background: currentColor; margin: 5px 0; }

.hero { min-height: 100svh; position: relative; display: flex; align-items: center; overflow: hidden; }
.hero-image { position: absolute; inset: 0; background: url("assets/orbit-debris-hero.png") 64% center/cover no-repeat; transform: scale(1.02); }
.hero-shade { position: absolute; inset: 0; background: linear-gradient(90deg, rgba(3,7,12,.96) 0%, rgba(3,7,12,.82) 35%, rgba(3,7,12,.15) 70%), linear-gradient(0deg, var(--bg) 0%, transparent 22%, rgba(2,6,11,.22) 100%); }
.hero-content { position: relative; z-index: 2; width: min(92vw, var(--max)); margin: auto; padding: 132px 0 110px; }
.eyebrow, .kicker { margin: 0 0 28px; font: 700 .72rem/1.3 system-ui, sans-serif; letter-spacing: .24em; color: var(--cyan); }
.eyebrow span { display: inline-flex; align-items: center; gap: 12px; }
.eyebrow span::before { content: ""; width: 38px; height: 1px; background: var(--cyan); }
.hero h1 { margin: 0; font: 800 clamp(4.7rem, 12vw, 10.8rem)/.76 "Arial Narrow", "Roboto Condensed", Impact, sans-serif; letter-spacing: -.045em; }
.hero h1 span { display: block; }
.hero h1 span:last-child { color: transparent; -webkit-text-stroke: 1.5px rgba(238,246,251,.72); margin-left: .22em; }
.hero-lead { margin: 42px 0 8px; font-size: clamp(1.25rem, 2.1vw, 1.8rem); font-weight: 700; letter-spacing: .08em; }
.hero-copy { max-width: 580px; margin: 0; color: #aebdca; font-size: 1rem; }
.scroll-cue { margin-top: 44px; display: inline-flex; align-items: center; gap: 14px; text-decoration: none; font: 700 .65rem/1 system-ui; letter-spacing: .2em; color: var(--amber); }
.scroll-cue i { display: block; width: 54px; height: 1px; background: var(--amber); position: relative; }
.scroll-cue i::after { content: ""; position: absolute; right: 0; top: -3px; width: 7px; height: 7px; border-right: 1px solid var(--amber); border-bottom: 1px solid var(--amber); transform: rotate(-45deg); }
.hero-meta { position: absolute; z-index: 2; bottom: 32px; right: 4vw; display: flex; gap: 28px; color: rgba(221,235,243,.58); font: 600 .6rem/1 system-ui; letter-spacing: .15em; }

.section { position: relative; max-width: var(--max); margin: 0 auto; padding: 140px 4vw; }
.section::before { content: ""; position: absolute; top: 0; left: 4vw; right: 4vw; height: 1px; background: var(--line); }
.section-index { position: absolute; top: 140px; right: 4vw; color: rgba(206,229,241,.08); font: 800 clamp(5rem, 11vw, 10rem)/1 system-ui; }
.section-heading { position: relative; z-index: 1; max-width: 820px; margin-bottom: 70px; }
.section-heading h2, .infra-copy h2 { margin: 0; font-size: clamp(2.2rem, 5vw, 4.7rem); line-height: 1.16; letter-spacing: -.04em; }
h2 em { color: var(--amber-soft); font-style: normal; }
.intro-grid { display: grid; grid-template-columns: .9fr 1.1fr; gap: clamp(60px, 10vw, 150px); align-items: start; }
.prose { max-width: 520px; color: var(--muted); }
.prose .lead { color: var(--text); font-size: 1.25rem; line-height: 1.75; font-weight: 600; }
.object-list { border-top: 1px solid var(--line); }
.object-list > div { display: grid; grid-template-columns: 44px 1fr auto; align-items: center; gap: 14px; padding: 24px 0; border-bottom: 1px solid var(--line); }
.object-list span { color: var(--amber); font: 700 .68rem/1 system-ui; }
.object-list b { font-size: .96rem; }
.object-list small { color: #668092; font: 700 .6rem/1 system-ui; letter-spacing: .12em; }

.numbers { background: #08111c; border-block: 1px solid var(--line); padding: 120px max(4vw, calc((100vw - var(--max)) / 2)); }
.numbers-head { display: flex; align-items: end; justify-content: space-between; gap: 40px; margin-bottom: 54px; }
.numbers-head h2 { margin: 0; max-width: 650px; font-size: clamp(2rem, 4vw, 3.8rem); line-height: 1.2; }
.stat-grid { display: grid; grid-template-columns: repeat(4, 1fr); border-left: 1px solid var(--line); }
.stat { min-height: 250px; display: flex; flex-direction: column; justify-content: flex-end; padding: 28px; border-right: 1px solid var(--line); border-block: 1px solid var(--line); background: linear-gradient(180deg, rgba(255,255,255,.015), transparent); }
.stat-number { margin: 0 0 24px; color: var(--text); font: 700 clamp(2.2rem, 4.1vw, 4.6rem)/1 "Arial Narrow", sans-serif; letter-spacing: -.06em; white-space: nowrap; }
.stat h3 { margin: 0; font-size: .9rem; line-height: 1.5; }
.stat small { margin-top: 8px; color: #648096; font: 700 .58rem/1 system-ui; letter-spacing: .12em; }
.stat-accent { background: var(--amber); color: #161008; }
.stat-accent .stat-number, .stat-accent small { color: #161008; }
.source-note { margin: 20px 0 0; color: #607588; font: 600 .58rem/1.5 system-ui; letter-spacing: .1em; }

.speed-panel { position: relative; display: grid; grid-template-columns: .7fr 1fr; gap: 70px; align-items: end; padding: 50px; background: linear-gradient(135deg, #0d1c29, #081019); overflow: hidden; border: 1px solid var(--line); }
.speed-value { display: flex; align-items: baseline; gap: 12px; position: relative; z-index: 1; }
.speed-value span { font: 800 clamp(4rem, 10vw, 9rem)/.8 "Arial Narrow", sans-serif; letter-spacing: -.07em; }
.speed-value b { color: var(--cyan); font-size: 1.4rem; }
.speed-panel > p { position: relative; z-index: 1; max-width: 480px; margin: 0; color: #b0c0cc; }
.orbit-line { position: absolute; width: 72%; height: 220px; border: 1px solid rgba(87,201,239,.2); border-radius: 50%; right: -10%; top: -55%; transform: rotate(-8deg); }
.orbit-line i { position: absolute; width: 8px; height: 8px; border-radius: 50%; background: var(--amber); left: 13%; bottom: 24px; box-shadow: 0 0 18px var(--amber); }
.size-grid { display: grid; grid-template-columns: repeat(3, 1fr); margin-top: 28px; gap: 1px; background: var(--line); border: 1px solid var(--line); }
.size-card { min-height: 360px; padding: 36px; background: var(--bg); position: relative; overflow: hidden; }
.size-dot { border-radius: 50%; background: var(--text); box-shadow: 0 0 24px rgba(238,246,251,.35); margin-bottom: 52px; }
.size-dot.mm { width: 4px; height: 4px; }
.size-dot.cm { width: 22px; height: 22px; }
.size-dot.ten-cm { width: 74px; height: 74px; background: var(--amber); box-shadow: 0 0 40px rgba(255,180,74,.4); }
.size-card .size { margin: 0; font: 700 3.2rem/1 system-ui; }
.size-card .size span { color: var(--cyan); font-size: .9rem; margin-left: 5px; }
.size-card h3 { margin: 28px 0 8px; font-size: 1.1rem; }
.size-card > p:last-child { margin: 0; color: var(--muted); font-size: .9rem; }
.size-card.dangerous { background: #151109; }
.size-card.dangerous .size span { color: var(--amber); }

.chain { max-width: none; padding-left: max(4vw, calc((100vw - var(--max)) / 2)); padding-right: max(4vw, calc((100vw - var(--max)) / 2)); background: #070d16; }
.chain .section-index { right: max(4vw, calc((100vw - var(--max)) / 2)); }
.chain .section-heading { max-width: var(--max); margin-inline: auto; }
.chain-layout { max-width: var(--max); margin: 0 auto; display: grid; grid-template-columns: 1.1fr .9fr; gap: 100px; align-items: center; }
.chain-diagram { aspect-ratio: 1; max-width: 560px; position: relative; display: grid; place-items: center; }
.earth-core { width: 128px; height: 128px; display: grid; place-items: center; border-radius: 50%; background: radial-gradient(circle at 35% 35%, #337b9f, #0d2a3d 55%, #07111c); box-shadow: 0 0 60px rgba(87,201,239,.22); font: 700 .65rem/1 system-ui; letter-spacing: .14em; color: rgba(255,255,255,.65); }
.orbit-ring { position: absolute; border: 1px solid rgba(87,201,239,.22); border-radius: 50%; transform: rotate(-18deg); }
.ring-a { width: 70%; height: 36%; }
.ring-b { width: 96%; height: 55%; transform: rotate(22deg); }
.debris { position: absolute; width: 9px; height: 4px; background: #b7c3cb; box-shadow: 0 0 6px rgba(255,255,255,.3); }
.d1 { top: 25%; left: 15%; transform: rotate(32deg); }.d2 { top: 33%; right: 12%; }.d3 { bottom: 23%; left: 20%; transform: rotate(-18deg); }
.d4 { bottom: 29%; right: 18%; transform: rotate(54deg); }.d5 { top: 14%; left: 54%; }.d6 { bottom: 14%; left: 48%; transform: rotate(25deg); }
.impact { position: absolute; right: 8%; top: 40%; width: 78px; height: 78px; display: grid; place-items: center; border: 1px solid var(--amber); color: var(--amber); border-radius: 50%; font: 700 .55rem/1 system-ui; letter-spacing: .12em; box-shadow: 0 0 50px rgba(255,180,74,.17), inset 0 0 25px rgba(255,180,74,.1); animation: pulse 2.6s ease-in-out infinite; }
@keyframes pulse { 50% { transform: scale(1.07); box-shadow: 0 0 70px rgba(255,180,74,.35), inset 0 0 30px rgba(255,180,74,.14); } }
.chain-steps article { display: grid; grid-template-columns: 54px 1fr; gap: 20px; padding: 28px 0; border-bottom: 1px solid var(--line); }
.chain-steps article > span { color: var(--amber); font: 700 .7rem/1 system-ui; padding-top: 7px; }
.chain-steps h3 { margin: 0 0 8px; font-size: 1.1rem; }
.chain-steps p { margin: 0; color: var(--muted); font-size: .9rem; }
.warning { max-width: var(--max); margin: 80px auto 0; padding: 30px 34px; border-left: 3px solid var(--amber); background: rgba(255,180,74,.06); color: #d7e2e8; font-size: 1.05rem; }

.infrastructure { display: grid; grid-template-columns: .95fr 1.05fr; gap: 100px; align-items: start; }
.infra-copy { position: sticky; top: 120px; }
.infra-copy > p:last-child { margin-top: 38px; max-width: 520px; color: var(--muted); }
.infra-lines { padding-top: 28px; }
.infra-lines > div { display: grid; grid-template-columns: 95px 1fr; gap: 24px; align-items: center; min-height: 112px; border-top: 1px solid var(--line); }
.infra-lines > div:last-child { border-bottom: 1px solid var(--line); }
.infra-lines span { color: #6f8595; font: 700 .65rem/1 system-ui; letter-spacing: .15em; }
.infra-lines p { margin: 0; }
.infra-lines .highlight { padding: 20px; margin-inline: -20px; background: var(--amber); color: #171108; border: 0; }
.infra-lines .highlight span { color: #171108; }

.cleanup { display: grid; grid-template-columns: 1fr 1fr; gap: 100px; align-items: center; }
.cleanup-visual { min-height: 520px; position: relative; background: radial-gradient(circle at 35% 48%, rgba(87,201,239,.14), transparent 34%), #07101b; border: 1px solid var(--line); overflow: hidden; }
.cleanup-visual::before { content: "RENDEZVOUS / CAPTURE / REENTRY"; position: absolute; left: 24px; top: 24px; color: #5b7181; font: 700 .58rem/1 system-ui; letter-spacing: .14em; }
.target { position: absolute; left: 18%; top: 42%; width: 74px; height: 74px; border: 1px solid var(--cyan); display: grid; place-items: center; transform: rotate(8deg); box-shadow: 0 0 40px rgba(87,201,239,.18); }
.target i { position: absolute; inset: -18px; border: 1px dashed rgba(87,201,239,.3); }
.target span { font: 700 .5rem/1 system-ui; letter-spacing: .1em; }
.approach-line { position: absolute; left: 36%; right: 33%; top: 49%; border-top: 1px dashed rgba(255,180,74,.5); }
.craft { position: absolute; right: 16%; top: 39%; width: 92px; height: 92px; border: 2px solid var(--amber); border-radius: 16px; box-shadow: 0 0 35px rgba(255,180,74,.2); }
.craft span { position: absolute; top: 36px; width: 54px; border-top: 3px solid var(--amber); }
.craft span:first-child { left: -48px; transform: rotate(25deg); transform-origin: right; }.craft span:nth-child(2) { right: -48px; transform: rotate(-25deg); transform-origin: left; }
.craft b { position: absolute; width: 16px; height: 16px; border-radius: 50%; background: var(--amber); top: 36px; left: 36px; box-shadow: 0 0 20px var(--amber); }
.cleanup-copy h2 { margin: 0 0 32px; font-size: clamp(2rem, 4vw, 3.7rem); line-height: 1.2; }
.cleanup-copy > p:last-of-type { color: var(--muted); }
.cleanup-copy dl { margin: 42px 0 0; border-top: 1px solid var(--line); }
.cleanup-copy dl div { display: flex; justify-content: space-between; gap: 24px; padding: 16px 0; border-bottom: 1px solid var(--line); }
.cleanup-copy dt { color: #647d8f; font: 700 .65rem/1 system-ui; letter-spacing: .13em; }
.cleanup-copy dd { margin: 0; color: var(--amber); font: 700 .7rem/1 system-ui; letter-spacing: .08em; }

.mission { position: relative; min-height: 100svh; padding: 150px max(4vw, calc((100vw - var(--max)) / 2)); display: grid; place-items: center; overflow: hidden; background: #090d13; }
.mission::before { content: ""; position: absolute; inset: 0; background: radial-gradient(circle at 77% 20%, rgba(255,180,74,.12), transparent 32%), radial-gradient(circle at 18% 76%, rgba(87,201,239,.12), transparent 35%); }
.mission-grid { position: absolute; inset: 0; opacity: .2; background-image: linear-gradient(var(--line) 1px, transparent 1px), linear-gradient(90deg, var(--line) 1px, transparent 1px); background-size: 80px 80px; mask-image: linear-gradient(to bottom, transparent, #000 20%, #000 80%, transparent); }
.mission-content { position: relative; z-index: 1; width: 100%; max-width: var(--max); }
.mission h2 { margin: 0 0 50px; font: 800 clamp(4rem, 10vw, 9rem)/.82 "Arial Narrow", Impact, sans-serif; letter-spacing: -.055em; }
.mission h2 em { color: transparent; -webkit-text-stroke: 1.5px var(--amber); }
.mission-content > p:not(.kicker) { max-width: 720px; color: var(--muted); }
.mission-content .mission-lead { color: var(--text) !important; font-size: 1.25rem; font-weight: 700; }
.closing { padding: 170px 4vw; text-align: center; background: var(--amber); color: #171108; }
.closing > p:first-child { margin: 0 0 24px; font: 800 .68rem/1 system-ui; letter-spacing: .22em; }
.closing h2 { margin: 0 auto; max-width: 1000px; font-size: clamp(2.2rem, 5vw, 5.4rem); line-height: 1.22; letter-spacing: -.045em; }
.closing h2 em { color: #171108; text-decoration: underline; text-decoration-thickness: .05em; text-underline-offset: .16em; }
.closing-line { width: 1px; height: 90px; margin: 58px auto; background: rgba(23,17,8,.35); }
.final-message { margin: 0; font-size: clamp(1.3rem, 2.4vw, 2rem); font-weight: 800; letter-spacing: .12em; }

footer { max-width: var(--max); margin: auto; padding: 70px 4vw; display: grid; grid-template-columns: 1fr 1.5fr auto; gap: 50px; align-items: start; }
.footer-brand b, .footer-brand span { display: block; }.footer-brand b { font-size: .9rem; letter-spacing: .1em; }.footer-brand span { color: var(--muted); font-size: .65rem; }
.references p { margin: 0 0 12px; color: #6b8293; font: 700 .6rem/1 system-ui; letter-spacing: .14em; }
.references a { display: block; width: fit-content; color: var(--muted); font-size: .75rem; text-decoration-color: rgba(153,170,184,.4); }
.references a:hover { color: var(--cyan); }
.back-top { font: 700 .62rem/1 system-ui; letter-spacing: .12em; color: var(--amber); text-decoration: none; }

.reveal { opacity: 0; transform: translateY(22px); transition: opacity .75s ease, transform .75s cubic-bezier(.2,.7,.2,1); }
.reveal.visible { opacity: 1; transform: none; }

@media (max-width: 900px) {
  .hero-meta { display: none; }
  .stat-grid { grid-template-columns: 1fr 1fr; }
  .intro-grid, .chain-layout, .infrastructure, .cleanup { grid-template-columns: 1fr; gap: 60px; }
  .infra-copy { position: static; }
  .size-grid { grid-template-columns: 1fr; }
  .size-card { min-height: 280px; }
  footer { grid-template-columns: 1fr 1fr; }
  .back-top { grid-column: 2; }
}

@media (max-width: 640px) {
  body { font-size: 16px; }
  .site-header { padding: 15px 18px; }
  .nav-toggle { display: block; position: relative; z-index: 2; }
  .site-nav { position: absolute; inset: 0 0 auto; padding: 82px 24px 30px; flex-direction: column; gap: 24px; background: rgba(5,10,18,.97); border-bottom: 1px solid var(--line); transform: translateY(-110%); transition: transform .3s; }
  .site-nav.open { transform: translateY(0); }
  .brand b { font-size: .7rem; }
  .hero-content { width: auto; margin: 0; padding-inline: 22px; }
  .hero-image { background-position: 67% center; opacity: .72; }
  .hero-shade { background: linear-gradient(90deg, rgba(3,7,12,.92), rgba(3,7,12,.2)), linear-gradient(0deg, var(--bg), transparent 38%); }
  .hero h1 { font-size: clamp(4rem, 25vw, 6.7rem); }
  .hero h1 span:last-child { margin-left: 0; }
  .hero-copy { max-width: 92%; font-size: .94rem; }
  .section { padding: 100px 22px; }
  .section::before { left: 22px; right: 22px; }
  .section-index { top: 90px; right: 22px; }
  .section-heading { margin-bottom: 52px; }
  .section-heading h2, .infra-copy h2 { font-size: 2.45rem; }
  .object-list > div { grid-template-columns: 34px 1fr; }
  .object-list small { display: none; }
  .numbers { padding: 92px 22px; }
  .numbers-head { display: block; }
  .stat-grid { grid-template-columns: 1fr; border-bottom: 0; }
  .stat { min-height: 190px; }
  .stat-number { font-size: 3.5rem; }
  .speed-panel { grid-template-columns: 1fr; gap: 32px; padding: 30px 24px; }
  .speed-value span { font-size: 5.2rem; }
  .size-card { padding: 30px 26px; }
  .chain { padding-inline: 22px; }
  .chain .section-index { right: 22px; }
  .chain-diagram { width: 100%; }
  .warning { margin-top: 50px; }
  .infra-lines > div { grid-template-columns: 72px 1fr; }
  .cleanup-visual { min-height: 390px; }
  .mission { padding: 120px 22px; }
  .mission h2 { font-size: clamp(3.6rem, 19vw, 6rem); }
  .closing { padding: 120px 22px; }
  footer { grid-template-columns: 1fr; padding: 55px 22px; }
  .back-top { grid-column: 1; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
  .reveal { opacity: 1; transform: none; }
}


/* Official-site integration */
.official-return{display:inline-flex;align-items:center;gap:.5rem;margin-bottom:1.4rem;color:#49c6e5;text-decoration:none;font-weight:800;letter-spacing:.12em;font-size:.75rem}
.official-return:hover{color:#fff}