:root {
  --ink: #17252b;
  --muted: #5a696f;
  --navy: #0c2a3a;
  --teal: #087b83;
  --teal-dark: #05646b;
  --teal-soft: #e3f2f1;
  --yellow: #f2c94c;
  --coral: #df6b52;
  --paper: #f4f6f3;
  --white: #ffffff;
  --line: #d9e0dd;
  --shadow: 0 12px 30px rgba(17, 40, 48, 0.1);
  --content: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--white);
  font-family: Pretendard, "Noto Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: 0;
  word-break: keep-all;
  overflow-wrap: break-word;
}

body.nav-open {
  overflow: hidden;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
}

button,
input,
textarea,
select {
  font: inherit;
  letter-spacing: 0;
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 1000;
  padding: 10px 14px;
  color: var(--white);
  background: var(--ink);
  transform: translateY(-150%);
}

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

.container {
  width: min(calc(100% - 40px), var(--content));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: 76px;
  background: rgba(255, 255, 255, 0.97);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 76px;
}

.brand {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
}

.brand img {
  width: 172px;
  height: auto;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 28px;
}

.site-nav a {
  position: relative;
  color: #25363d;
  font-size: 15px;
  font-weight: 700;
  text-decoration: none;
}

.site-nav a::after {
  position: absolute;
  right: 0;
  bottom: -9px;
  left: 0;
  height: 2px;
  background: var(--teal);
  content: "";
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 160ms ease;
}

.site-nav a:hover::after,
.site-nav a[aria-current="page"]::after {
  transform: scaleX(1);
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  color: var(--ink);
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 4px;
  cursor: pointer;
}

.nav-toggle span {
  font-size: 24px;
  line-height: 1;
}

.hero {
  position: relative;
  display: flex;
  min-height: 480px;
  align-items: center;
  color: var(--white);
  background-image: url("images/01-main-01-network.jpg");
  background-position: center;
  background-size: cover;
}

.hero::before,
.page-hero::before {
  position: absolute;
  inset: 0;
  background: rgba(6, 25, 34, 0.74);
  content: "";
}

.hero-content,
.page-hero .container {
  position: relative;
  z-index: 1;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--yellow);
  font-size: 14px;
  font-weight: 800;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 760px;
  margin: 0;
  font-size: 52px;
  line-height: 1.22;
  letter-spacing: 0;
}

.hero-lead {
  max-width: 680px;
  margin: 22px 0 0;
  color: #e6eef0;
  font-size: 19px;
  line-height: 1.75;
}

.hero-actions,
.inline-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 11px 19px;
  border: 1px solid transparent;
  border-radius: 4px;
  font-size: 15px;
  font-weight: 800;
  line-height: 1.4;
  text-decoration: none;
  transition: background 160ms ease, border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

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

.button-primary {
  color: #142329;
  background: var(--yellow);
}

.button-primary:hover {
  background: #ffda61;
}

.button-secondary {
  color: var(--white);
  background: transparent;
  border-color: rgba(255, 255, 255, 0.65);
}

.button-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--white);
}

.button-teal {
  color: var(--white);
  background: var(--teal);
}

.button-teal:hover {
  background: var(--teal-dark);
}

.section {
  padding: 78px 0;
}

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

.section-dark {
  color: var(--white);
  background: var(--navy);
}

.section-header {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 32px;
  margin-bottom: 32px;
}

.section-header > div {
  max-width: 710px;
}

.section-kicker {
  margin: 0 0 8px;
  color: var(--teal);
  font-size: 14px;
  font-weight: 800;
}

.section-dark .section-kicker {
  color: var(--yellow);
}

.section h2,
.article h2 {
  margin: 0;
  font-size: 34px;
  line-height: 1.35;
  letter-spacing: 0;
}

.section-header p {
  margin: 12px 0 0;
  color: var(--muted);
}

.section-dark .section-header p {
  color: #cbd8dc;
}

.directory-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.directory-card {
  position: relative;
  display: flex;
  min-height: 248px;
  flex-direction: column;
  padding: 26px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: 0 5px 18px rgba(27, 50, 57, 0.05);
}

.directory-card:nth-child(2) {
  border-top: 4px solid var(--coral);
}

.directory-card:nth-child(3) {
  border-top: 4px solid var(--yellow);
}

.directory-card:nth-child(4) {
  border-top: 4px solid var(--teal);
}

.directory-card:first-child {
  border-top: 4px solid var(--navy);
}

.card-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 20px;
}

.card-number {
  color: var(--teal);
  font-size: 13px;
  font-weight: 900;
}

.card-tag {
  padding: 4px 9px;
  color: #385057;
  background: var(--paper);
  border-radius: 3px;
  font-size: 12px;
  font-weight: 700;
}

.directory-card h3 {
  margin: 0;
  font-size: 23px;
  line-height: 1.4;
  letter-spacing: 0;
}

.directory-card p {
  margin: 12px 0 22px;
  color: var(--muted);
  font-size: 15px;
}

.card-link {
  display: inline-flex;
  align-items: center;
  align-self: flex-start;
  margin-top: auto;
  color: var(--teal-dark);
  font-size: 15px;
  font-weight: 900;
  text-decoration: none;
}

.card-link:hover {
  text-decoration: underline;
  text-underline-offset: 5px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.feature-item {
  padding: 30px;
  border-right: 1px solid var(--line);
}

.feature-item:last-child {
  border-right: 0;
}

.feature-item strong {
  display: block;
  margin-bottom: 10px;
  color: var(--teal-dark);
  font-size: 15px;
}

.feature-item h3 {
  margin: 0 0 12px;
  font-size: 22px;
  line-height: 1.4;
  letter-spacing: 0;
}

.feature-item p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 28px;
}

.step {
  padding-top: 20px;
  border-top: 3px solid var(--teal);
}

.step-number {
  display: block;
  margin-bottom: 8px;
  color: var(--yellow);
  font-size: 13px;
  font-weight: 900;
}

.step h3 {
  margin: 0 0 10px;
  font-size: 21px;
  letter-spacing: 0;
}

.step p {
  margin: 0;
  color: #cbd8dc;
  font-size: 15px;
}

.notice-band {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 40px;
  align-items: center;
  padding: 36px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.notice-band h2 {
  margin: 0;
  font-size: 28px;
  letter-spacing: 0;
}

.notice-band p {
  margin: 10px 0 0;
  color: var(--muted);
}

.notice-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.notice-list li {
  position: relative;
  padding: 9px 0 9px 22px;
  border-bottom: 1px solid var(--line);
}

.notice-list li:last-child {
  border-bottom: 0;
}

.notice-list li::before {
  position: absolute;
  top: 19px;
  left: 2px;
  width: 7px;
  height: 7px;
  background: var(--coral);
  border-radius: 50%;
  content: "";
}

.faq-list {
  border-top: 1px solid var(--line);
}

.faq-list details {
  border-bottom: 1px solid var(--line);
}

.faq-list summary {
  position: relative;
  padding: 22px 46px 22px 0;
  font-size: 18px;
  font-weight: 800;
  cursor: pointer;
  list-style: none;
}

.faq-list summary::-webkit-details-marker {
  display: none;
}

.faq-list summary::after {
  position: absolute;
  top: 20px;
  right: 6px;
  color: var(--teal);
  content: "+";
  font-size: 24px;
  line-height: 1;
}

.faq-list details[open] summary::after {
  content: "−";
}

.faq-list details p {
  max-width: 820px;
  margin: -4px 0 24px;
  color: var(--muted);
}

.page-hero {
  position: relative;
  display: flex;
  min-height: 330px;
  align-items: center;
  color: var(--white);
  background-image: url("images/01-main-01-network.jpg");
  background-position: center 46%;
  background-size: cover;
}

.page-hero h1 {
  max-width: 790px;
  margin: 0;
  font-size: 42px;
  line-height: 1.3;
  letter-spacing: 0;
}

.page-hero p:last-child {
  max-width: 710px;
  margin: 16px 0 0;
  color: #dce7e9;
  font-size: 18px;
}

.breadcrumbs {
  padding: 16px 0;
  color: var(--muted);
  background: var(--paper);
  border-bottom: 1px solid var(--line);
  font-size: 13px;
}

.breadcrumbs a {
  color: var(--teal-dark);
  text-decoration: none;
}

.content-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 285px;
  gap: 54px;
  align-items: start;
}

.article h2 {
  margin-top: 56px;
  margin-bottom: 18px;
  font-size: 29px;
}

.article h2:first-child {
  margin-top: 0;
}

.article h3 {
  margin: 32px 0 10px;
  font-size: 21px;
  line-height: 1.45;
  letter-spacing: 0;
}

.article p {
  margin: 0 0 18px;
}

.article ul,
.article ol {
  margin: 0 0 24px;
  padding-left: 24px;
}

.article li {
  margin-bottom: 8px;
}

.article a:not(.button):not(.directory-card a) {
  color: var(--teal-dark);
  font-weight: 700;
  text-underline-offset: 4px;
}

.article-lead {
  padding-left: 20px;
  color: #33474e;
  border-left: 4px solid var(--teal);
  font-size: 19px;
}

.aside-nav {
  position: sticky;
  top: 100px;
  padding: 22px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
}

.aside-nav strong {
  display: block;
  margin-bottom: 12px;
  font-size: 15px;
}

.aside-nav a {
  display: block;
  padding: 9px 0;
  color: #405259;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
  text-decoration: none;
}

.aside-nav a:last-child {
  border-bottom: 0;
}

.aside-nav a:hover {
  color: var(--teal-dark);
}

.definition-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 26px 0 34px;
  overflow: hidden;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: 6px;
}

.definition-item {
  min-height: 150px;
  padding: 22px;
  background: var(--white);
}

.definition-item strong {
  display: block;
  margin-bottom: 8px;
  color: var(--teal-dark);
}

.definition-item p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

.status-list {
  margin: 26px 0 34px;
  border-top: 1px solid var(--line);
}

.status-row {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr);
  gap: 20px;
  padding: 17px 0;
  border-bottom: 1px solid var(--line);
}

.status-code {
  color: var(--teal-dark);
  font-weight: 900;
}

.status-row p {
  margin: 0;
  color: var(--muted);
}

.link-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 28px;
}

.link-strip a {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  padding: 8px 14px;
  color: var(--teal-dark);
  background: var(--teal-soft);
  border: 1px solid #c6e0de;
  border-radius: 4px;
  font-size: 14px;
  font-weight: 800;
  text-decoration: none;
}

.link-strip a:hover {
  background: #d2e9e7;
}

.cta-band {
  padding: 54px 0;
  color: var(--white);
  background: var(--teal-dark);
}

.cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
}

.cta-inner h2 {
  margin: 0;
  font-size: 28px;
  letter-spacing: 0;
}

.cta-inner p {
  margin: 8px 0 0;
  color: #d7e7e8;
}

.site-footer {
  color: #d4dfe2;
  background: #13232a;
}

.footer-main {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr 0.8fr;
  gap: 56px;
  padding: 56px 0 42px;
}

.footer-brand img {
  width: 180px;
}

.footer-brand p {
  max-width: 460px;
  margin: 18px 0 0;
  color: #aebec3;
  font-size: 14px;
}

.footer-col strong {
  display: block;
  margin-bottom: 14px;
  color: var(--white);
  font-size: 14px;
}

.footer-col a {
  display: block;
  margin: 8px 0;
  color: #b9c8cc;
  font-size: 14px;
  text-decoration: none;
}

.footer-col a:hover {
  color: var(--white);
}

.footer-bottom {
  padding: 18px 0 24px;
  color: #91a3a8;
  border-top: 1px solid #2d3c42;
  font-size: 12px;
}

.footer-bottom p {
  margin: 0;
}

.updated-note {
  color: var(--muted);
  font-size: 13px;
}

:focus-visible {
  outline: 3px solid var(--yellow);
  outline-offset: 3px;
}

@media (max-width: 900px) {
  .hero h1 {
    font-size: 42px;
  }

  .feature-grid,
  .steps {
    grid-template-columns: 1fr;
  }

  .feature-item {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .feature-item:last-child {
    border-bottom: 0;
  }

  .content-layout {
    grid-template-columns: 1fr;
  }

  .aside-nav {
    position: static;
    order: -1;
  }
}

@media (max-width: 760px) {
  body {
    font-size: 16px;
    line-height: 1.7;
  }

  .container {
    width: min(calc(100% - 28px), var(--content));
  }

  .site-header,
  .header-inner {
    height: 66px;
    min-height: 66px;
  }

  .brand img {
    width: 142px;
  }

  .nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .site-nav {
    position: fixed;
    top: 66px;
    right: 0;
    left: 0;
    display: none;
    max-height: calc(100vh - 66px);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 16px 20px 24px;
    overflow-y: auto;
    background: var(--white);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
  }

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

  .site-nav a {
    padding: 14px 2px;
    border-bottom: 1px solid var(--line);
  }

  .site-nav a::after {
    display: none;
  }

  .hero {
    min-height: 430px;
    background-position: 58% center;
  }

  .hero h1 {
    font-size: 34px;
    line-height: 1.3;
  }

  .hero-lead {
    margin-top: 16px;
    font-size: 17px;
  }

  .hero-actions .button {
    flex: 1 1 150px;
  }

  .section {
    padding: 58px 0;
  }

  .section-header {
    display: block;
  }

  .section h2,
  .article h2 {
    font-size: 27px;
  }

  .directory-grid,
  .definition-grid,
  .notice-band {
    grid-template-columns: 1fr;
  }

  .directory-card {
    min-height: 230px;
    padding: 22px;
  }

  .notice-band {
    gap: 18px;
  }

  .page-hero {
    min-height: 300px;
  }

  .page-hero h1 {
    font-size: 32px;
  }

  .page-hero p:last-child {
    font-size: 16px;
  }

  .content-layout {
    gap: 36px;
  }

  .article h2 {
    margin-top: 44px;
  }

  .status-row {
    grid-template-columns: 70px minmax(0, 1fr);
    gap: 12px;
  }

  .cta-inner {
    display: block;
  }

  .cta-inner .button {
    margin-top: 22px;
  }

  .footer-main {
    grid-template-columns: 1fr;
    gap: 30px;
  }
}

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

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}