:root {
  color-scheme: light;
  --black: #000000;
  --ink: #171717;
  --muted: #595959;
  --line: #b8b8b8;
  --soft: #f3f3f3;
  --white: #ffffff;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--white);
  color: var(--ink);
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.55;
}

main {
  flex: 1;
  display: flex;
}

a {
  color: inherit;
}

a:focus-visible {
  outline: 3px solid var(--black);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 20;
  padding: 10px 14px;
  background: var(--black);
  color: var(--white);
  transform: translateY(-150%);
}

.skip-link:focus {
  transform: translateY(0);
}

.shell {
  width: min(1120px, calc(100% - 48px));
  margin: 0 auto;
}

.site-header {
  border-bottom: 1px solid var(--black);
}

.header-inner {
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.wordmark {
  font-size: 19px;
  font-weight: 800;
  line-height: 1;
  text-decoration: none;
}

.primary-nav {
  display: flex;
  align-items: center;
  gap: 28px;
  font-size: 14px;
}

.primary-nav a {
  text-underline-offset: 5px;
  text-decoration-thickness: 1px;
}

.primary-nav a:hover {
  text-decoration-thickness: 2px;
}

.introduction {
  width: 100%;
  flex: 1;
  border-bottom: 1px solid var(--black);
}

.introduction-inner {
  padding: 68px 0 72px;
}

.edition,
.section-number,
.control-label {
  margin: 0;
  color: var(--muted);
  font-family: "Courier New", Courier, monospace;
  font-size: 13px;
  font-weight: 700;
  line-height: 1.4;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  letter-spacing: 0;
}

h1 {
  max-width: 930px;
  margin: 22px 0 34px;
  color: var(--black);
  font-size: 72px;
  font-weight: 800;
  line-height: 1.02;
}

.lead {
  max-width: 820px;
  margin: 0;
  font-size: 21px;
  line-height: 1.55;
}

.primary-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 38px;
}

.action {
  min-height: 46px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 18px;
  border: 1px solid var(--black);
  font-size: 15px;
  font-weight: 700;
  text-decoration: none;
}

.action-primary {
  background: var(--black);
  color: var(--white);
}

.action-primary:hover {
  background: var(--white);
  color: var(--black);
}

.action-secondary {
  background: var(--white);
  color: var(--black);
}

.action-secondary:hover {
  background: var(--soft);
}

.architecture,
.documents {
  padding: 76px 0 84px;
  border-bottom: 1px solid var(--black);
}

.section-introduction {
  display: grid;
  grid-template-columns: 90px minmax(0, 760px);
  gap: 28px;
  align-items: start;
  margin-bottom: 52px;
}

h2 {
  margin: -8px 0 14px;
  color: var(--black);
  font-size: 38px;
  font-weight: 800;
  line-height: 1.15;
}

.section-introduction p:last-child,
.participation-inner > div > p {
  max-width: 720px;
  margin: 0;
  color: var(--muted);
  font-size: 18px;
}

.capability-map {
  display: grid;
  grid-template-columns: minmax(210px, 1fr) 86px 230px 86px minmax(210px, 1fr);
  grid-template-rows: auto auto;
  align-items: stretch;
  margin: 0;
}

.capability-group {
  border-top: 2px solid var(--black);
  border-bottom: 2px solid var(--black);
}

.capability-group h3 {
  min-height: 60px;
  display: flex;
  align-items: center;
  margin: 0;
  padding: 12px 16px;
  border-bottom: 1px solid var(--black);
  color: var(--black);
  font-size: 15px;
  line-height: 1.25;
  text-transform: uppercase;
}

.capability-group p {
  min-height: 64px;
  display: flex;
  align-items: center;
  margin: 0;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  font-size: 15px;
  line-height: 1.35;
}

.capability-group p:last-child {
  border-bottom: 0;
}

.control-plane {
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-height: 254px;
  padding: 26px 22px;
  border: 3px solid var(--black);
  background: var(--black);
  color: var(--white);
  text-align: center;
}

.control-plane .control-label {
  color: var(--white);
}

.control-plane h3 {
  margin: 20px 0 28px;
  font-size: 27px;
  line-height: 1.1;
}

.control-plane p:last-child {
  margin: 0;
  font-size: 14px;
}

.relationship {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 0;
}

.relationship::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  border-top: 1px solid var(--black);
}

.relationship::after {
  content: "";
  position: absolute;
  top: calc(50% - 4px);
  right: 2px;
  width: 8px;
  height: 8px;
  border-top: 1px solid var(--black);
  border-right: 1px solid var(--black);
  transform: rotate(45deg);
}

.relationship span {
  position: relative;
  z-index: 1;
  max-width: 76px;
  padding: 4px 5px;
  background: var(--white);
  color: var(--muted);
  font-family: "Courier New", Courier, monospace;
  font-size: 10px;
  line-height: 1.2;
  text-align: center;
  text-transform: uppercase;
}

.capability-map figcaption {
  grid-column: 1 / -1;
  max-width: 760px;
  margin-top: 24px;
  color: var(--muted);
  font-size: 14px;
}

.document-list {
  margin: 0;
  padding: 0;
  border-top: 2px solid var(--black);
  list-style: none;
}

.document-list li {
  border-bottom: 1px solid var(--black);
}

.document-list a {
  min-height: 84px;
  display: grid;
  grid-template-columns: 64px minmax(220px, 1fr) minmax(280px, 1.4fr) 34px;
  gap: 20px;
  align-items: center;
  padding: 15px 10px;
  text-decoration: none;
}

.document-list a:hover {
  background: var(--soft);
}

.document-number {
  color: var(--muted);
  font-family: "Courier New", Courier, monospace;
  font-size: 13px;
}

.document-title {
  color: var(--black);
  font-size: 18px;
  font-weight: 700;
}

.document-purpose {
  color: var(--muted);
  font-size: 15px;
}

.document-arrow {
  color: var(--black);
  font-family: "Courier New", Courier, monospace;
  font-size: 18px;
  text-align: right;
}

.participation {
  padding: 76px 0 82px;
  border-bottom: 1px solid var(--black);
}

.participation-inner {
  display: grid;
  grid-template-columns: 90px minmax(0, 650px) minmax(220px, 1fr);
  gap: 28px;
  align-items: start;
}

.participation-links {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 14px;
  padding-top: 3px;
}

.participation-links a {
  font-weight: 700;
  text-underline-offset: 5px;
}

.site-footer {
  padding: 30px 0 36px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 30px;
  color: var(--muted);
  font-size: 13px;
}

.footer-inner p {
  margin: 0;
}

.footer-inner a {
  text-underline-offset: 3px;
}

@media (max-width: 900px) {
  h1 {
    font-size: 58px;
  }

  .capability-map {
    grid-template-columns: minmax(185px, 1fr) 76px 205px 76px minmax(185px, 1fr);
  }

  .document-list a {
    grid-template-columns: 48px minmax(180px, 1fr) minmax(220px, 1.2fr) 24px;
    gap: 14px;
  }

  .participation-inner {
    grid-template-columns: 64px minmax(0, 1fr);
  }

  .participation-links {
    grid-column: 2;
    margin-top: 12px;
  }
}

@media (max-width: 780px) {
  .shell {
    width: min(100% - 32px, 1120px);
  }

  .header-inner {
    min-height: 58px;
    gap: 18px;
  }

  .primary-nav {
    gap: 16px;
    font-size: 13px;
  }

  .primary-nav a:first-child {
    display: none;
  }

  .introduction-inner {
    padding: 48px 0 54px;
  }

  h1 {
    margin: 18px 0 26px;
    font-size: 44px;
    line-height: 1.04;
  }

  .lead {
    font-size: 18px;
  }

  .primary-actions {
    margin-top: 30px;
  }

  .action {
    width: 100%;
  }

  .architecture,
  .documents,
  .participation {
    padding: 58px 0 64px;
  }

  .section-introduction,
  .participation-inner {
    grid-template-columns: 1fr;
    gap: 18px;
    margin-bottom: 38px;
  }

  h2 {
    margin-top: 0;
    font-size: 31px;
  }

  .section-introduction p:last-child,
  .participation-inner > div > p {
    font-size: 17px;
  }

  .capability-map {
    grid-template-columns: 1fr;
    grid-template-rows: auto 58px auto 58px auto auto;
  }

  .capability-foundation {
    grid-row: 1;
  }

  .relationship-in {
    grid-row: 2;
  }

  .control-plane {
    grid-row: 3;
    min-height: 210px;
  }

  .relationship-out {
    grid-row: 4;
  }

  .capability-use {
    grid-row: 5;
  }

  .relationship::before {
    top: 0;
    bottom: 0;
    left: 50%;
    right: auto;
    border-top: 0;
    border-left: 1px solid var(--black);
  }

  .relationship::after {
    top: auto;
    right: auto;
    bottom: 2px;
    left: calc(50% - 4px);
    transform: rotate(135deg);
  }

  .relationship span {
    max-width: none;
    padding: 4px 8px;
  }

  .capability-map figcaption {
    grid-column: 1;
    grid-row: 6;
  }

  .document-list a {
    min-height: 0;
    grid-template-columns: 36px minmax(0, 1fr) 24px;
    grid-template-rows: auto auto;
    gap: 5px 12px;
    padding: 18px 6px;
  }

  .document-number {
    grid-row: 1 / 3;
    align-self: start;
    padding-top: 4px;
  }

  .document-purpose {
    grid-column: 2;
  }

  .document-arrow {
    grid-column: 3;
    grid-row: 1 / 3;
  }

  .participation-inner {
    margin-bottom: 0;
  }

  .participation-links {
    grid-column: 1;
    margin-top: 8px;
  }

  .footer-inner {
    flex-direction: column;
    gap: 10px;
  }
}

@media (max-width: 420px) {
  .primary-nav a:nth-child(2) {
    display: none;
  }

  h1 {
    font-size: 38px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

@media print {
  .site-header,
  .primary-actions,
  .participation-links {
    display: none;
  }

  .architecture,
  .documents,
  .participation {
    break-inside: avoid;
  }
}