:root {
  color-scheme: light;
  --ink: #111827;
  --ink-strong: #071424;
  --muted: #526071;
  --subtle: #748196;
  --line: #d7dee8;
  --line-strong: #b8c4d2;
  --panel: #f4f7fa;
  --panel-warm: #fbfaf7;
  --paper: #ffffff;
  --blue: #123f6d;
  --blue-dark: #082844;
  --blue-soft: #e7f0f8;
  --cyan: #087b8f;
  --cyan-soft: #dff4f7;
  --amber: #b97916;
  --green: #166c58;
  --shadow: 0 18px 42px rgba(8, 40, 68, 0.1);
  --radius: 8px;
  --max: 1180px;
  --step--1: 0.88rem;
  --step-0: 1rem;
  --step-1: 1.15rem;
  --step-2: 1.42rem;
  --step-3: 1.85rem;
  --step-4: 2.45rem;
  --step-5: 3.55rem;
  --space-1: 0.5rem;
  --space-2: 0.75rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2rem;
  --space-6: 3rem;
  --space-7: 4.5rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--panel);
  color: var(--ink);
  font-family: "Aptos", "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  font-size: var(--step-0);
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

img,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--cyan);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--blue);
}

a:focus-visible,
button:focus-visible {
  outline: 3px solid rgba(8, 123, 143, 0.38);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -5rem;
  z-index: 20;
  background: var(--ink-strong);
  color: white;
  padding: 0.65rem 0.9rem;
  text-decoration: none;
}

.skip-link:focus {
  top: 1rem;
}

.site-header {
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(18px);
}

.header-inner,
.section-inner,
.footer-inner,
.hero-grid,
.content-shell {
  width: min(var(--max), calc(100% - 32px));
  margin: 0 auto;
}

.header-inner {
  min-height: 80px;
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  color: var(--ink);
  text-decoration: none;
  min-width: max-content;
}

.brand img {
  width: 52px;
  height: 52px;
}

.brand strong,
.brand span {
  display: block;
}

.brand strong {
  color: var(--ink-strong);
  font-size: 1.04rem;
  line-height: 1.05;
}

.brand span {
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.25;
}

.nav-toggle {
  display: none;
  margin-left: auto;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink);
  min-width: 44px;
  min-height: 44px;
  font-size: 1.2rem;
}

.site-nav {
  margin-left: auto;
}

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 0.12rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.site-nav a {
  display: block;
  color: var(--ink);
  font-weight: 700;
  font-size: 0.91rem;
  text-decoration: none;
  padding: 0.65rem 0.72rem;
  border-radius: 999px;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--blue);
  background: var(--blue-soft);
}

.hero,
.page-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
}

.hero {
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.98) 0%, rgba(255, 255, 255, 0.95) 49%, rgba(231, 240, 248, 0.78) 100%),
    url("assets/images/rds-forum-2025-members.png") center bottom / cover no-repeat;
}

.hero::before,
.page-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(90deg, rgba(18, 63, 109, 0.05) 1px, transparent 1px),
    linear-gradient(0deg, rgba(18, 63, 109, 0.05) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: linear-gradient(90deg, transparent, #000 22%, #000 78%, transparent);
}

.hero-grid {
  min-height: 640px;
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) 390px;
  gap: var(--space-6);
  align-items: center;
  padding: var(--space-7) 0;
}

.eyebrow {
  color: var(--cyan);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin: 0 0 var(--space-2);
}

h1,
h2,
h3 {
  color: var(--ink-strong);
  font-family: "Aptos Display", "Aptos", "Segoe UI", ui-sans-serif, system-ui, sans-serif;
  line-height: 1.08;
  margin: 0;
  letter-spacing: 0;
}

h1 {
  font-size: clamp(3rem, 6vw, 5.8rem);
  max-width: 12ch;
}

h2 {
  font-size: clamp(2rem, 3.1vw, 3rem);
}

h3 {
  font-size: var(--step-2);
}

p {
  margin: 0;
}

p + p {
  margin-top: var(--space-3);
}

.lead {
  color: #2c3a4c;
  font-size: clamp(1.13rem, 1.65vw, 1.34rem);
  max-width: 66ch;
  margin-top: var(--space-3);
}

.intro {
  color: #27384a;
  font-size: var(--step-1);
}

.hero-actions,
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-5);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0.72rem 1rem;
  border: 1px solid var(--blue);
  border-radius: var(--radius);
  background: var(--blue);
  color: white;
  font-weight: 800;
  text-decoration: none;
  box-shadow: 0 8px 18px rgba(18, 63, 109, 0.15);
}

.button:hover {
  background: var(--blue-dark);
  color: white;
}

.button.secondary {
  background: white;
  color: var(--blue);
  box-shadow: none;
}

.button.secondary:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.notice,
.card,
.download-card,
.stat,
.article,
.side-nav,
.tech-panel {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.notice {
  box-shadow: var(--shadow);
  padding: var(--space-5);
  border-top: 5px solid var(--cyan);
}

.notice .date {
  color: var(--blue);
  display: block;
  font-size: var(--step-3);
  font-weight: 800;
  line-height: 1.14;
  margin: var(--space-2) 0;
}

.hero-visual {
  margin-top: var(--space-6);
  max-width: 650px;
}

.signal-card {
  background: rgba(255, 255, 255, 0.82);
  border: 1px solid rgba(18, 63, 109, 0.16);
  border-radius: var(--radius);
  padding: var(--space-4);
  box-shadow: 0 14px 34px rgba(8, 40, 68, 0.08);
}

.signal-card svg {
  width: 100%;
}

.signal-labels {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-2);
  margin-top: var(--space-3);
}

.signal-labels span {
  border-left: 3px solid var(--cyan);
  color: var(--muted);
  font-size: var(--step--1);
  padding-left: var(--space-2);
}

.section {
  padding: var(--space-7) 0;
  background: var(--paper);
}

.section.alt {
  background: var(--panel);
}

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

.section.band h2,
.section.band h3 {
  color: white;
}

.section.band p,
.section.band .card p {
  color: #d8e3ef;
}

.section-head {
  display: grid;
  grid-template-columns: minmax(0, 0.85fr) minmax(0, 1fr);
  gap: var(--space-6);
  align-items: end;
  margin-bottom: var(--space-5);
}

.section-head p {
  color: var(--muted);
}

.grid {
  display: grid;
  gap: var(--space-3);
}

.grid.three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid.two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.card,
.download-card,
.stat,
.tech-panel {
  padding: var(--space-4);
}

.card.feature {
  position: relative;
  overflow: hidden;
  min-height: 210px;
}

.card.feature::before {
  content: attr(data-index);
  display: inline-grid;
  place-items: center;
  width: 2.25rem;
  height: 2.25rem;
  margin-bottom: var(--space-4);
  border-radius: 50%;
  background: var(--cyan-soft);
  color: var(--cyan);
  font-weight: 850;
}

.card.feature::after {
  content: "";
  position: absolute;
  inset: auto 0 0;
  height: 4px;
  background: linear-gradient(90deg, var(--blue), var(--cyan));
}

.card h3,
.download-card h3 {
  margin-bottom: var(--space-2);
}

.card p,
.download-card p,
.stat span {
  color: var(--muted);
}

.video-card img {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  object-position: center;
  margin-bottom: var(--space-3);
}

.stat {
  display: grid;
  grid-template-rows: auto 1fr;
  gap: var(--space-2);
  min-height: 180px;
}

.stat strong {
  display: block;
  color: var(--blue);
  font-size: var(--step-4);
  font-weight: 850;
  line-height: 1;
}

.stat em {
  color: var(--cyan);
  font-style: normal;
  font-weight: 800;
}

.download-card {
  position: relative;
  padding: var(--space-5);
}

.download-card::before {
  content: "";
  display: block;
  width: 52px;
  height: 4px;
  margin-bottom: var(--space-4);
  background: var(--cyan);
}

.page-hero {
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.98), rgba(231, 240, 248, 0.82)),
    var(--paper);
}

.page-hero .section-inner {
  padding: var(--space-7) 0 var(--space-6);
}

.page-hero h1 {
  max-width: 16ch;
}

.content-shell {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: var(--space-5);
  padding: var(--space-6) 0 var(--space-7);
}

.side-nav {
  position: sticky;
  top: 104px;
  align-self: start;
  padding: var(--space-2);
}

.side-nav a {
  display: block;
  color: var(--ink);
  text-decoration: none;
  padding: 0.62rem 0.72rem;
  border-left: 3px solid transparent;
  border-radius: 0 6px 6px 0;
  font-weight: 700;
}

.side-nav a:hover,
.side-nav a[aria-current="page"] {
  color: var(--blue);
  background: var(--blue-soft);
  border-left-color: var(--cyan);
}

.article {
  padding: clamp(1.25rem, 3vw, 2.65rem);
}

.article > * + * {
  margin-top: var(--space-4);
}

.article h2 {
  font-size: clamp(1.55rem, 2vw, 2.15rem);
  margin-top: var(--space-6);
}

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

.article img {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.image-viewer-trigger {
  cursor: zoom-in;
}

.image-viewer-trigger:hover {
  border-color: var(--cyan);
}

.image-viewer-trigger:focus-visible {
  outline: 3px solid rgba(8, 123, 143, 0.38);
  outline-offset: 4px;
}

.has-image-viewer {
  overflow: hidden;
}

.image-viewer {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: grid;
  place-items: center;
  padding: clamp(1rem, 3vw, 2.5rem);
  background: rgba(7, 20, 36, 0.86);
}

.image-viewer[hidden] {
  display: none;
}

.image-viewer-frame {
  display: grid;
  gap: var(--space-3);
  max-width: min(1120px, 100%);
  max-height: 100%;
  margin: 0;
}

.image-viewer-frame img {
  max-width: 100%;
  max-height: min(78vh, 820px);
  border-radius: var(--radius);
  background: white;
  box-shadow: 0 22px 70px rgba(0, 0, 0, 0.32);
  object-fit: contain;
}

.image-viewer-frame figcaption {
  color: white;
  font-size: var(--step--1);
  text-align: center;
}

.image-viewer-close {
  position: fixed;
  top: 1rem;
  right: 1rem;
  display: inline-grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border: 1px solid rgba(255, 255, 255, 0.42);
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.95);
  color: var(--ink-strong);
  font-size: 1.7rem;
  line-height: 1;
  cursor: pointer;
}

.image-viewer-close:hover {
  background: white;
}

.article-media {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 210px;
  gap: var(--space-5);
  align-items: start;
}

.article-media p {
  margin: 0;
}

.article-media p + p,
.article-media p + .document-list {
  margin-top: var(--space-3);
}

.article-media img {
  width: 100%;
}

.profile-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 240px;
  gap: var(--space-5);
  align-items: start;
}

.profile-photo {
  margin: 0;
}

.profile-photo img {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
}

.profile-photo figcaption {
  color: var(--muted);
  font-size: var(--step--1);
  margin-top: var(--space-2);
}

.check-list {
  margin: var(--space-3) 0 0;
  padding-left: 1.2rem;
}

.check-list li + li {
  margin-top: var(--space-2);
}

.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr) minmax(0, 1fr);
  gap: var(--space-3);
}

address {
  color: var(--muted);
  font-style: normal;
}

.callout {
  border-left: 5px solid var(--amber);
  background: #fff8ea;
  padding: var(--space-4);
  border-radius: 0 var(--radius) var(--radius) 0;
}

.document-list {
  display: grid;
  gap: var(--space-2);
}

.document-list a {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--space-3);
  align-items: center;
  padding: var(--space-3) var(--space-4);
  background: var(--panel-warm);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--ink);
  text-decoration: none;
}

.document-list a:hover {
  border-color: var(--cyan);
  color: var(--blue);
  background: white;
}

.document-list strong {
  line-height: 1.35;
}

.document-list span,
.tag {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 1.7rem;
  padding: 0.18rem 0.55rem;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
  white-space: nowrap;
}

.timeline {
  display: grid;
  gap: var(--space-3);
  margin-top: var(--space-4);
}

.timeline-item {
  display: grid;
  grid-template-columns: 6.8rem minmax(0, 1fr);
  gap: var(--space-4);
  padding: var(--space-3) 0 var(--space-3) var(--space-3);
  border-left: 3px solid var(--cyan);
}

.timeline-item time {
  color: var(--blue);
  font-weight: 850;
}

.timeline-item p {
  color: var(--muted);
}

.tech-panel {
  background: linear-gradient(135deg, #ffffff, var(--blue-soft));
}

.subcarrier-diagram {
  margin-top: var(--space-4);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: white;
  padding: var(--space-4);
}

.subcarrier-diagram img {
  width: 100%;
  border: 0;
  border-radius: 0;
  box-shadow: none;
}

.sample-small {
  color: var(--muted);
  font-size: var(--step--1);
}

.site-footer {
  background: var(--ink-strong);
  color: white;
  padding: var(--space-6) 0;
}

.footer-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--space-5);
  align-items: start;
}

.site-footer p {
  color: #c6d0dc;
  max-width: 62ch;
}

.site-footer .footer-updated {
  color: #9fb0c3;
  font-size: var(--step--1);
  margin-top: var(--space-2);
}

.site-footer a {
  color: white;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

@media (max-width: 940px) {
  .header-inner {
    flex-wrap: wrap;
    padding: 0.7rem 0;
  }

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

  .site-nav {
    display: none;
    width: 100%;
    margin: 0;
  }

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

  .site-nav ul {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-2);
  }

  .site-nav a {
    border: 1px solid var(--line);
    border-radius: var(--radius);
  }

  .hero-grid,
  .section-head,
  .content-shell,
  .footer-inner,
  .article-media,
  .profile-header,
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .hero-grid {
    min-height: 0;
    padding: var(--space-6) 0;
  }

  .grid.three,
  .grid.two {
    grid-template-columns: 1fr 1fr;
  }

  .side-nav {
    position: static;
  }

  .article-media img {
    max-width: 280px;
  }

  .profile-photo img {
    max-width: 280px;
  }
}

@media (max-width: 560px) {
  .header-inner,
  .section-inner,
  .footer-inner,
  .hero-grid,
  .content-shell {
    width: min(100% - 24px, var(--max));
  }

  .brand span span {
    display: none;
  }

  .site-nav ul,
  .grid.three,
  .grid.two,
  .signal-labels,
  .timeline-item {
    grid-template-columns: 1fr;
  }

  h1 {
    font-size: 2.55rem;
  }

  .section {
    padding: var(--space-6) 0;
  }

  .document-list a {
    grid-template-columns: 1fr;
  }

  .document-list span {
    justify-self: start;
  }
}