:root {
  color-scheme: dark;
  --page: #0b1120;
  --panel: #101827;
  --panel-raised: #141e2e;
  --line: #263447;
  --text: #e7edf2;
  --muted: #9aa9b9;
  --quiet: #718297;
  --green: #21c894;
  --cyan: #5ad7e7;
  --sans: 'Instrument Sans', sans-serif;
  --display: 'Bricolage Grotesque', sans-serif;
  --mono: 'JetBrains Mono', monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 5rem; }
body {
  margin: 0;
  background:
    radial-gradient(ellipse at 77% 14%, rgba(26, 82, 85, .12), transparent 35rem),
    var(--page);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
body::before {
  position: fixed;
  z-index: -1;
  inset: 0;
  pointer-events: none;
  content: "";
  background-image: linear-gradient(rgba(104, 132, 159, .035) 1px, transparent 1px), linear-gradient(90deg, rgba(104, 132, 159, .035) 1px, transparent 1px);
  background-size: 54px 54px;
  mask-image: linear-gradient(to bottom, #000, transparent 75%);
}
a { color: inherit; }
a:focus-visible, summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 4px;
  border-radius: 3px;
}
.skip-link {
  position: fixed;
  z-index: 10;
  top: 12px;
  left: 12px;
  padding: .7rem 1rem;
  transform: translateY(-150%);
  background: var(--green);
  color: #07130f;
  font-weight: 700;
}
.skip-link:focus { transform: translateY(0); }
.site-header {
  position: relative;
  z-index: 1;
  border-bottom: 1px solid var(--line);
  background: rgba(11, 17, 32, .88);
}
.header-inner, .footer-inner, .footer-meta, .page-shell {
  width: min(1160px, calc(100% - 48px));
  margin-inline: auto;
}
.header-inner {
  min-height: 76px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand { display: inline-flex; align-items: center; gap: 12px; text-decoration: none; }
.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 3px;
  padding: 6px;
  border: 1px solid #354458;
  border-radius: 5px;
  background: var(--panel);
}
.brand-mark i { border-radius: 1px; background: var(--green); }
.brand-mark i:nth-child(2), .brand-mark i:nth-child(3) { opacity: .68; background: var(--cyan); }
.brand-mark i:nth-child(4) { opacity: .45; }
.brand strong {
  display: block;
  font-family: var(--display);
  font-size: 15px;
  line-height: 1.2;
  letter-spacing: -.02em;
}
.brand small {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font: 9px/1.2 var(--mono);
  letter-spacing: .1em;
  text-transform: uppercase;
}
.header-action, .primary-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  min-height: 44px;
  padding: 0 17px;
  border: 1px solid transparent;
  border-radius: 4px;
  background: var(--green);
  color: #07150f;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  transition: background-color .18s ease, border-color .18s ease, transform .18s ease;
}
.header-action:hover, .primary-action:hover { background: #49d8aa; transform: translateY(-1px); }
.page-shell { padding-top: 25px; padding-bottom: 100px; }
.breadcrumbs { color: var(--quiet); font: 11px/1.5 var(--mono); }
.breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.breadcrumbs li { display: inline-flex; align-items: center; gap: 9px; }
.breadcrumbs li + li::before { content: "/"; color: #4d6074; }
.breadcrumbs a { color: var(--muted); text-decoration: none; }
.breadcrumbs a:hover { color: var(--cyan); }
.breadcrumbs [aria-current="page"] { color: var(--text); }
.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(275px, .55fr);
  align-items: center;
  gap: clamp(42px, 8vw, 112px);
  padding: clamp(48px, 9vw, 106px) 0 75px;
}
.eyebrow {
  margin: 0 0 15px;
  color: var(--cyan);
  font: 10px/1.4 var(--mono);
  letter-spacing: .16em;
  text-transform: uppercase;
}
.hero h1 {
  max-width: 800px;
  margin: 0;
  font: 800 clamp(42px, 6.2vw, 76px)/.99 var(--display);
  letter-spacing: -.055em;
}
.hero-intro {
  max-width: 700px;
  margin: 25px 0 0;
  color: #b5c1cd;
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.55;
}
.hero-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; margin-top: 29px; }
.primary-action { min-height: 50px; padding-inline: 21px; }
.secondary-action {
  padding: 12px 4px;
  color: var(--muted);
  font-size: 14px;
  text-decoration: underline;
  text-decoration-color: #42536a;
  text-underline-offset: 5px;
}
.secondary-action:hover { color: var(--text); text-decoration-color: var(--cyan); }
.scope-note {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  max-width: 570px;
  margin: 25px 0 0;
  color: var(--muted);
  font-size: 13px;
}
.scope-mark { flex: 0 0 7px; height: 7px; margin-top: 7px; border-radius: 50%; background: var(--green); }
.hero-rail {
  position: relative;
  min-height: 335px;
  overflow: hidden;
  padding: 19px;
  border: 1px solid #2a3a4c;
  background: linear-gradient(150deg, rgba(20, 31, 47, .96), rgba(12, 19, 32, .96));
}
.hero-rail::after {
  position: absolute;
  inset: 0;
  pointer-events: none;
  content: "";
  background: linear-gradient(115deg, transparent 42%, rgba(90, 215, 231, .035), transparent 72%);
}
.rail-label { display: flex; justify-content: space-between; gap: 10px; color: var(--quiet); font: 9px var(--mono); letter-spacing: .12em; }
.rail-diagram { position: relative; height: 116px; margin: 16px 0 9px; border-block: 1px solid rgba(69, 92, 117, .42); }
.rail-node { position: absolute; z-index: 1; width: 12px; height: 12px; border: 2px solid var(--cyan); border-radius: 50%; background: var(--panel); }
.node-a { top: 23px; left: 13%; }
.node-b { top: 73px; left: 48%; border-color: var(--green); }
.node-c { top: 23px; right: 13%; }
.rail-line { position: absolute; height: 1px; transform-origin: left; background: #446377; }
.line-a { top: 30px; left: 16%; width: 36%; transform: rotate(17deg); }
.line-b { top: 78px; left: 51%; width: 36%; transform: rotate(-17deg); }
.line-c { top: 30px; left: 16%; width: 70%; border-top: 1px dashed #354b60; background: transparent; }
.rail-steps { display: grid; gap: 0; margin: 0; padding: 0; list-style: none; }
.rail-steps li { display: flex; align-items: center; gap: 15px; padding: 9px 0; border-bottom: 1px solid rgba(58, 76, 96, .54); font-size: 13px; }
.rail-steps b { color: var(--green); font: 10px var(--mono); }
.hero-rail > p { margin: 12px 0 0; color: var(--quiet); font-size: 11px; line-height: 1.5; }
.article-body { border-top: 1px solid var(--line); }
.content-section {
  display: grid;
  grid-template-columns: 80px minmax(0, 760px);
  gap: clamp(18px, 4vw, 55px);
  padding: 51px 0 54px;
  border-bottom: 1px solid var(--line);
}
.section-index { padding-top: 10px; color: var(--green); font: 12px var(--mono); }
.section-copy h2, .section-heading h2, .sources h2 {
  margin: 0;
  color: var(--text);
  font: 700 clamp(25px, 3.5vw, 37px)/1.12 var(--display);
  letter-spacing: -.035em;
}
.section-copy p { max-width: 735px; margin: 18px 0 0; color: #b1becb; line-height: 1.75; }
.section-copy ul { display: grid; gap: 10px; margin: 20px 0 0; padding: 0; list-style: none; }
.section-copy li { position: relative; padding-left: 20px; color: #b1becb; }
.section-copy li::before { position: absolute; top: .72em; left: 0; width: 6px; height: 1px; background: var(--green); content: ""; }
.related-section, .faq-section { padding-top: 74px; }
.section-heading { max-width: 720px; margin-bottom: 25px; }
.section-heading .eyebrow { margin-bottom: 12px; }
.section-heading > p { color: var(--muted); }
.link-grid, .metro-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; margin: 0; padding: 0; list-style: none; }
.link-card, .metro-list a {
  display: flex;
  min-height: 86px;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  padding: 16px 19px;
  border: 1px solid var(--line);
  background: rgba(16, 24, 39, .7);
  text-decoration: none;
  transition: border-color .18s ease, background-color .18s ease;
}
.link-card:hover, .metro-list a:hover { border-color: #3b766f; background: var(--panel-raised); }
.link-card-title, .metro-list a { color: var(--text); font-weight: 600; }
.link-card-title { display: flex; justify-content: space-between; gap: 14px; }
.link-card-title span, .metro-list a span { color: var(--green); }
.link-card-description { color: var(--muted); font-size: 13px; font-weight: 400; }
.metro-list { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.metro-list a { min-height: 58px; flex-direction: row; align-items: center; justify-content: space-between; font-size: 14px; }
.faq-section { display: grid; grid-template-columns: minmax(220px, .7fr) minmax(0, 1.3fr); gap: 42px; }
.faq-section .section-heading { margin: 0; }
.faq-list { border-top: 1px solid var(--line); }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-item summary { position: relative; padding: 19px 36px 19px 0; cursor: pointer; font-weight: 600; list-style: none; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { position: absolute; top: 17px; right: 4px; color: var(--green); font: 20px var(--mono); content: "+"; }
.faq-item[open] summary::after { content: "−"; }
.faq-item p { margin: -4px 25px 20px 0; color: var(--muted); font-size: 14px; }
.sources { margin-top: 75px; padding: 25px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.sources h2 { font-size: 18px; }
.sources ul { display: flex; flex-wrap: wrap; gap: 8px 24px; margin: 15px 0 0; padding-left: 18px; color: var(--green); }
.sources li { padding-left: 3px; }
.sources a { color: #b8c6d4; font-size: 13px; text-underline-offset: 3px; }
.sources a:hover { color: var(--cyan); }
.external-note { color: var(--quiet); font-size: 11px; }
.updated { margin: 24px 0 0; color: var(--quiet); font: 10px var(--mono); }
.site-footer { border-top: 1px solid var(--line); background: rgba(7, 12, 23, .55); }
.footer-inner { display: grid; grid-template-columns: 1fr 1.1fr auto; align-items: center; gap: 26px; padding-block: 32px; }
.footer-inner p { max-width: 360px; margin: 0; color: var(--muted); font-size: 12px; }
.footer-inner > a:last-child { color: var(--green); font-size: 13px; text-decoration: none; }
.footer-inner > a:last-child:hover { color: var(--cyan); }
.footer-meta { display: flex; justify-content: space-between; gap: 20px; padding-block: 14px 20px; border-top: 1px solid rgba(38, 52, 71, .65); color: var(--quiet); font: 9px var(--mono); }

@media (max-width: 760px) {
  .header-inner, .footer-inner, .footer-meta, .page-shell { width: min(100% - 36px, 560px); }
  .header-inner { min-height: 68px; }
  .header-action { min-height: 40px; padding-inline: 11px; font-size: 12px; }
  .brand small { font-size: 8px; letter-spacing: .07em; }
  .hero { grid-template-columns: 1fr; gap: 35px; padding: 48px 0 53px; }
  .hero h1 { font-size: clamp(42px, 12vw, 62px); }
  .hero-rail { min-height: 0; }
  .content-section { grid-template-columns: 35px minmax(0, 1fr); gap: 13px; padding-block: 34px; }
  .section-index { font-size: 10px; }
  .link-grid, .metro-list { grid-template-columns: 1fr; }
  .faq-section { grid-template-columns: 1fr; gap: 23px; }
  .footer-inner { grid-template-columns: 1fr; gap: 17px; }
  .footer-meta { flex-direction: column; gap: 6px; }
}
@media (max-width: 390px) {
  .header-action { max-width: 114px; text-align: center; line-height: 1.25; }
  .brand { gap: 8px; }
  .brand strong { font-size: 13px; }
  .brand small { max-width: 180px; font-size: 7px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; }
}