:root {
  --bg: #f5f7f6;
  --surface: #ffffff;
  --surface-soft: #eef4f2;
  --ink: #14211f;
  --muted: #61716d;
  --line: #d8e2de;
  --primary: #0b6657;
  --primary-strong: #084c41;
  --accent: #1d5f9f;
  --accent-soft: #e8f1fb;
  --warn: #8a5b13;
  --warn-soft: #fff4dd;
  --ok: #10724f;
  --code: #102a43;
  --shadow: 0 18px 44px rgba(25, 45, 39, .08);
  --radius: 8px;
  --space-1: .5rem;
  --space-2: .75rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2rem;
  --space-6: 3rem;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
  overflow-x: hidden;
  max-width: 100%;
}

a {
  color: var(--primary);
  text-decoration-thickness: .08em;
  text-underline-offset: .18em;
}

a:hover {
  color: var(--primary-strong);
}

img,
svg {
  max-width: 100%;
}

button {
  font: inherit;
}

:focus-visible {
  outline: 3px solid rgba(29, 95, 159, .35);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: .5rem;
  z-index: 20;
  transform: translateY(-140%);
  background: var(--ink);
  color: #fff;
  padding: .45rem .7rem;
  border-radius: 6px;
}

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

.site-header {
  background: rgba(255, 255, 255, .92);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
}

.header-inner,
.footer-inner,
.section-inner,
.page-shell {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  min-width: 0;
  max-width: 100%;
}

.section-inner > *,
.page-shell > *,
.animation-app > *,
.animation-workspace > * {
  min-width: 0;
}

.header-inner {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: .65rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 800;
  letter-spacing: 0;
}

.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 8px;
  background: var(--primary);
  color: #fff;
  font-size: .9rem;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: .35rem;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.site-nav a {
  color: var(--muted);
  text-decoration: none;
  padding: .45rem .65rem;
  border-radius: 6px;
  font-size: .95rem;
  font-weight: 650;
  overflow-wrap: anywhere;
}

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

.hero {
  background:
    linear-gradient(120deg, rgba(11, 102, 87, .94), rgba(21, 60, 87, .92)),
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='1200' height='700' viewBox='0 0 1200 700'%3E%3Cg fill='none' stroke='%23ffffff' stroke-opacity='.18' stroke-width='2'%3E%3Cpath d='M90 130h220v110h210v-70h230v120h220'/%3E%3Cpath d='M130 430h180v-90h210v140h210v-80h260'/%3E%3Cpath d='M260 210v320M520 120v440M760 190v300M980 150v360'/%3E%3C/g%3E%3Cg fill='%23ffffff' fill-opacity='.28'%3E%3Ccircle cx='90' cy='130' r='10'/%3E%3Ccircle cx='310' cy='240' r='10'/%3E%3Ccircle cx='520' cy='170' r='10'/%3E%3Ccircle cx='750' cy='290' r='10'/%3E%3Ccircle cx='970' cy='290' r='10'/%3E%3Ccircle cx='130' cy='430' r='10'/%3E%3Ccircle cx='520' cy='480' r='10'/%3E%3Ccircle cx='990' cy='400' r='10'/%3E%3C/g%3E%3C/svg%3E");
  background-size: cover;
  color: #fff;
}

.hero .section-inner {
  min-height: min(540px, calc(100vh - 120px));
  display: grid;
  align-items: center;
  padding: var(--space-6) 0;
}

.hero-copy {
  max-width: 760px;
}

.eyebrow {
  margin: 0 0 var(--space-2);
  color: #d8f0eb;
  font-weight: 750;
  letter-spacing: .02em;
}

h1,
h2,
h3 {
  margin: 0;
  letter-spacing: 0;
  line-height: 1.25;
}

h1 {
  font-size: clamp(2rem, 7vw, 4.6rem);
  max-width: 10ch;
}

h2 {
  font-size: clamp(1.45rem, 3vw, 2.35rem);
}

h3 {
  font-size: 1.1rem;
}

p {
  margin: 0;
}

.lead {
  margin-top: var(--space-3);
  font-size: clamp(1.05rem, 2vw, 1.28rem);
  max-width: 780px;
  color: rgba(255, 255, 255, .9);
}

.hero-actions,
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-4);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: .65rem .95rem;
  border-radius: 7px;
  border: 1px solid transparent;
  background: var(--primary);
  color: #fff;
  text-decoration: none;
  font-weight: 750;
  cursor: pointer;
}

.button:hover {
  background: var(--primary-strong);
  color: #fff;
}

.button.secondary {
  background: #fff;
  color: var(--ink);
  border-color: rgba(255, 255, 255, .7);
}

.button.ghost {
  color: var(--primary);
  background: transparent;
  border-color: var(--line);
}

.button.ghost:hover {
  color: var(--ink);
  background: var(--surface-soft);
}

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

.section.alt {
  background: var(--surface);
  border-block: 1px solid var(--line);
}

.section-heading {
  display: grid;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
  max-width: 760px;
}

.section-heading 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,
.callout {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.card {
  padding: var(--space-4);
  box-shadow: var(--shadow);
}

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

.card h3 + p {
  margin-top: var(--space-1);
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: .45rem;
  margin-top: var(--space-3);
}

.tag {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: .15rem .55rem;
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--primary-strong);
  font-size: .82rem;
  font-weight: 750;
}

.curriculum-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.topic-group {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-3);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.topic-group h3 {
  display: flex;
  justify-content: space-between;
  gap: var(--space-2);
  align-items: baseline;
}

.topic-group h3 span {
  color: var(--primary);
  font-size: .86rem;
}

.coverage-list {
  margin: 0;
  padding-left: 1.1rem;
  color: var(--muted);
}

.coverage-list li + li {
  margin-top: .32rem;
}

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

.coverage-summary a {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: .65rem;
  align-items: center;
  min-height: 64px;
  padding: .85rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  text-decoration: none;
}

.coverage-summary a:hover {
  border-color: rgba(12, 101, 166, .35);
  box-shadow: var(--shadow);
}

.coverage-summary strong {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 999px;
  background: var(--primary);
  color: #fff;
}

.coverage-summary span {
  font-weight: 800;
  line-height: 1.2;
}

.coverage-summary small {
  color: var(--primary-strong);
  font-weight: 850;
}

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

.domain-detail {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  overflow: clip;
}

.domain-detail summary {
  display: flex;
  justify-content: space-between;
  gap: var(--space-2);
  align-items: center;
  min-height: 58px;
  padding: var(--space-3);
  cursor: pointer;
  font-weight: 850;
}

.domain-detail summary::marker {
  color: var(--primary);
}

.domain-detail summary strong {
  color: var(--primary-strong);
  font-size: .95rem;
}

.objective-list {
  display: grid;
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--line);
}

.objective {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr);
  gap: var(--space-3);
  padding: var(--space-3);
  background: #fff;
}

.objective-code {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  align-self: start;
  min-height: 32px;
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--primary-strong);
  font-size: .9rem;
  font-weight: 850;
}

.objective h3 {
  margin-bottom: .25rem;
  font-size: 1rem;
}

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

.objective-links {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin-top: .6rem;
}

.objective-links a,
.toc-list a {
  color: var(--primary-strong);
  font-weight: 800;
}

.study-band {
  display: grid;
  gap: .35rem;
  margin-top: var(--space-3);
  padding: var(--space-3);
  border-left: 4px solid var(--primary);
  border-radius: var(--radius);
  background: var(--surface-soft);
}

.study-band strong {
  color: var(--primary-strong);
}

.toc-list {
  display: grid;
  gap: .55rem;
  margin-top: var(--space-2);
}

.animation-intro {
  padding: var(--space-5) 0 var(--space-3);
}

.animation-app {
  display: grid;
  grid-template-columns: minmax(260px, 340px) minmax(0, 1fr);
  gap: var(--space-4);
  align-items: start;
  padding: 0 0 var(--space-6);
  min-width: 0;
}

.animation-browser,
.animation-workspace,
.animation-notes section {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.animation-browser {
  position: sticky;
  top: 96px;
  display: grid;
  gap: var(--space-3);
  max-height: calc(100vh - 120px);
  padding: var(--space-3);
  overflow: auto;
  min-width: 0;
}

.animation-search {
  display: grid;
  gap: .35rem;
  font-weight: 800;
}

.animation-search input {
  min-height: 44px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: .55rem .7rem;
  color: var(--ink);
  font: inherit;
}

.animation-mode-summary {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: .45rem;
}

.animation-kind-stat {
  display: grid;
  gap: .1rem;
  min-height: 58px;
  padding: .55rem;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface-soft);
}

.animation-kind-stat strong {
  color: var(--primary-strong);
  font-size: 1.15rem;
  line-height: 1;
}

.animation-kind-stat span {
  color: var(--muted);
  font-size: .72rem;
  font-weight: 850;
  line-height: 1.25;
}

.animation-filter-label {
  color: var(--muted);
  font-size: .82rem;
  font-weight: 850;
  letter-spacing: 0;
  text-transform: uppercase;
}

.animation-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: .45rem;
}

.animation-tab {
  min-height: 36px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: .35rem .65rem;
  background: var(--surface);
  color: var(--primary-strong);
  cursor: pointer;
  font-weight: 800;
  overflow-wrap: anywhere;
  line-break: anywhere;
  max-width: 100%;
}

.animation-tab:hover,
.animation-tab[aria-pressed="true"] {
  border-color: rgba(11, 102, 87, .35);
  background: var(--surface-soft);
  color: var(--ink);
}

.animation-topic-count {
  color: var(--muted);
  font-size: .9rem;
  font-weight: 750;
}

.animation-topic-list {
  display: grid;
  gap: .45rem;
}

.animation-topic-button {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: .15rem .6rem;
  align-items: center;
  min-height: 58px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: .55rem .65rem;
  background: var(--surface);
  color: var(--ink);
  text-align: left;
  cursor: pointer;
}

.animation-topic-button:hover,
.animation-topic-button[aria-current="true"] {
  border-color: rgba(11, 102, 87, .4);
  background: var(--surface-soft);
}

.animation-topic-button strong {
  display: inline-grid;
  place-items: center;
  min-width: 42px;
  min-height: 30px;
  border-radius: 999px;
  background: var(--primary);
  color: #fff;
  font-size: .85rem;
}

.animation-topic-button span {
  font-weight: 850;
  overflow-wrap: anywhere;
  line-break: anywhere;
}

.animation-topic-button small {
  grid-column: 2;
  color: var(--muted);
  font-size: .78rem;
}

.animation-topic-button em {
  grid-column: 2;
  width: fit-content;
  border-radius: 999px;
  padding: .12rem .45rem;
  background: var(--surface-soft);
  color: var(--primary-strong);
  font-size: .72rem;
  font-style: normal;
  font-weight: 850;
}

.animation-topic-kind.animate {
  background: #e8f1fb;
  color: #1d5f9f;
}

.animation-topic-kind.inspect {
  background: #fff4dd;
  color: #8a5b13;
}

.animation-workspace {
  display: grid;
  gap: var(--space-3);
  min-width: 0;
  padding: var(--space-3);
}

.animation-topic-header {
  display: grid;
  gap: var(--space-2);
}

.animation-topic-header h2 {
  font-size: clamp(1.45rem, 3vw, 2.35rem);
  overflow-wrap: anywhere;
  line-break: anywhere;
}

.animation-topic-header p {
  max-width: 760px;
  color: var(--muted);
  overflow-wrap: anywhere;
}

.learning-kind {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem .65rem;
  align-items: center;
  padding: .72rem .85rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface-soft);
}

.learning-kind strong {
  color: var(--primary-strong);
}

.learning-kind span {
  color: var(--muted);
  font-size: .9rem;
}

.learning-kind.animate {
  background: var(--accent-soft);
  border-color: rgba(29, 95, 159, .2);
}

.learning-kind.inspect {
  background: var(--warn-soft);
  border-color: rgba(138, 91, 19, .2);
}

.ccna-visualizer .visualizer-grid {
  min-height: 320px;
}

.ccna-visualizer .visualizer-stage,
.ccna-visualizer .visualizer-sequence-stage {
  min-height: 300px;
}

.ccna-visualizer.is-static [data-play],
.ccna-visualizer.is-static .progress {
  display: none;
}

.visualizer-static {
  display: block;
  padding: var(--space-3);
}

.visualizer-static-board {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
  height: 100%;
}

.visualizer-static-card {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: .35rem .75rem;
  align-content: start;
  min-height: 126px;
  padding: var(--space-3);
  border: 1px solid rgba(213, 239, 233, .14);
  border-radius: 8px;
  background: rgba(255, 255, 255, .06);
  color: rgba(238, 250, 247, .78);
}

.visualizer-static-card strong {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 999px;
  background: rgba(126, 228, 201, .14);
  color: #7ee4c9;
}

.visualizer-static-card h3 {
  align-self: center;
  color: #fff;
  font-size: 1rem;
}

.visualizer-static-card p {
  grid-column: 1 / -1;
  overflow-wrap: anywhere;
}

.visualizer-static-card.active {
  border-color: rgba(126, 228, 201, .7);
  background: rgba(126, 228, 201, .12);
  box-shadow: 0 0 0 1px rgba(126, 228, 201, .08), 0 18px 42px rgba(0, 0, 0, .18);
}

.animation-notes {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.animation-notes section {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-3);
}

.animation-notes h3 {
  font-size: 1rem;
}

.animation-notes ul {
  margin: 0;
  padding-left: 1.15rem;
  color: var(--muted);
}

.page-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: var(--space-5);
  padding: var(--space-5) 0 var(--space-6);
}

.article-header {
  padding: var(--space-5) 0 var(--space-3);
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}

.article-header .section-inner {
  display: grid;
  gap: var(--space-2);
}

.article-header h1 {
  max-width: 900px;
  font-size: clamp(1.9rem, 5vw, 3.6rem);
}

.article-header p {
  color: var(--muted);
  max-width: 760px;
}

.article {
  display: grid;
  gap: var(--space-5);
  min-width: 0;
}

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

.article-header p,
.article-section p,
.card p {
  overflow-wrap: anywhere;
}

.article-header h1,
.article-section h2,
.coverage-summary span,
.domain-detail summary span,
.objective h3 {
  overflow-wrap: anywhere;
  line-break: anywhere;
}

.article-section ul,
.article-section ol {
  margin: 0;
  padding-left: 1.25rem;
}

.article-section li + li {
  margin-top: .45rem;
}

.sidebar {
  position: sticky;
  top: 96px;
  align-self: start;
  display: grid;
  gap: var(--space-3);
}

.callout {
  padding: var(--space-3);
  background: var(--warn-soft);
  color: var(--warn);
}

.visualizer {
  background: #071f2b;
  border: 1px solid rgba(18, 78, 120, .22);
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 24px 60px rgba(6, 31, 43, .18);
  max-width: 100%;
}

.visualizer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(280px, .85fr);
  min-height: 340px;
}

.visualizer-stage {
  min-height: 340px;
  position: relative;
  padding: var(--space-4);
  overflow: hidden;
  min-width: 0;
  background:
    radial-gradient(circle at 18% 18%, rgba(69, 194, 168, .2), transparent 28%),
    radial-gradient(circle at 82% 24%, rgba(64, 132, 202, .2), transparent 30%),
    linear-gradient(90deg, rgba(170, 223, 211, .1) 1px, transparent 1px),
    linear-gradient(rgba(170, 223, 211, .1) 1px, transparent 1px),
    #071f2b;
  background-size: auto, auto, 34px 34px, 34px 34px;
}

.visualizer-sequence {
  display: grid;
  grid-template-rows: auto 1fr;
  padding: 0;
  background:
    radial-gradient(circle at 18% 18%, rgba(54, 231, 188, .13), transparent 28%),
    #071f2b;
}

.visualizer-lanes {
  display: grid;
  grid-template-columns: repeat(var(--lane-count), minmax(0, 1fr));
  gap: .5rem;
  padding: var(--space-3) var(--space-3) .8rem;
  border-bottom: 1px solid rgba(255, 255, 255, .1);
  background:
    linear-gradient(90deg, rgba(126, 228, 201, .1) 1px, transparent 1px),
    rgba(255, 255, 255, .02);
  background-size: calc(100% / var(--lane-count)) 100%;
}

.visualizer-lane {
  display: grid;
  justify-items: center;
  gap: .2rem;
  min-width: 0;
  color: rgba(237, 249, 246, .75);
  text-align: center;
  font-size: .74rem;
  font-weight: 750;
}

.visualizer-lane span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: min(108px, 100%);
  min-height: 44px;
  padding: .35rem .55rem;
  border-radius: 999px;
  background: linear-gradient(135deg, rgba(255, 255, 255, .98), rgba(226, 244, 239, .93));
  color: var(--ink);
  box-shadow: 0 16px 32px rgba(0, 0, 0, .22);
  font-size: .9rem;
  font-weight: 900;
}

.visualizer-lane small {
  max-width: 100%;
  overflow-wrap: anywhere;
}

.visualizer-sequence-stage {
  position: relative;
  min-height: 260px;
  padding: var(--space-3);
  background:
    linear-gradient(90deg, rgba(206, 236, 229, .1) 1px, transparent 1px),
    linear-gradient(rgba(206, 236, 229, .07) 1px, transparent 1px);
  background-size: calc(100% / var(--lane-count)) 100%, 32px 32px;
}

.visualizer-event {
  position: absolute;
  left: var(--left);
  right: calc(100% - var(--right));
  top: var(--top);
  min-width: 72px;
  height: 4px;
  border-radius: 999px;
  background: linear-gradient(90deg, #36e7bc, #6fa7e8);
  box-shadow: 0 0 18px rgba(54, 231, 188, .34);
  transform-origin: left center;
}

.visualizer-event.reverse {
  background: linear-gradient(90deg, #6fa7e8, #36e7bc);
}

.visualizer-event.active {
  animation: arpDraw .42s ease-out both;
}

.visualizer-event::before {
  content: attr(data-kind);
  position: absolute;
  left: 50%;
  top: -34px;
  transform: translateX(-50%);
  max-width: 160px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  border-radius: 999px;
  padding: .28rem .62rem;
  background: rgba(255, 255, 255, .96);
  color: var(--ink);
  box-shadow: 0 10px 22px rgba(0, 0, 0, .18);
  font-size: .78rem;
  font-weight: 900;
}

.visualizer-event::after {
  content: "";
  position: absolute;
  right: -2px;
  top: -4px;
  width: 12px;
  height: 12px;
  border-radius: 999px;
  background: #d9fff4;
  box-shadow: 0 0 14px rgba(217, 255, 244, .9);
}

.visualizer-event.reverse::after {
  left: -2px;
  right: auto;
}

.network-map {
  position: relative;
  min-height: 292px;
  isolation: isolate;
}

.network-map::before {
  content: "";
  position: absolute;
  inset: 18px;
  border: 1px solid rgba(204, 231, 225, .14);
  border-radius: 14px;
  pointer-events: none;
}

.network-map::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, transparent, rgba(255,255,255,.08), transparent);
  transform: translateX(-100%);
  animation: scan 5.8s linear infinite;
  pointer-events: none;
  z-index: 0;
}

.node {
  position: absolute;
  width: 132px;
  min-height: 84px;
  display: grid;
  align-content: center;
  justify-items: center;
  gap: .2rem;
  padding: .65rem;
  border: 1px solid rgba(190, 224, 216, .3);
  border-radius: 12px;
  background: linear-gradient(180deg, rgba(255, 255, 255, .96), rgba(232, 245, 242, .94));
  box-shadow: 0 18px 34px rgba(0, 0, 0, .24);
  text-align: center;
  font-weight: 800;
  font-size: .9rem;
  z-index: 3;
  transition: transform .28s ease, border-color .28s ease, box-shadow .28s ease;
}

.node::before {
  content: "";
  width: 34px;
  height: 22px;
  margin-bottom: .15rem;
  border-radius: 4px;
  background:
    linear-gradient(#123d52, #123d52) 50% 100% / 18px 3px no-repeat,
    linear-gradient(135deg, #0b6657, #1d5f9f);
  box-shadow: inset 0 0 0 2px rgba(255, 255, 255, .42);
}

.node small {
  display: block;
  color: var(--muted);
  font-weight: 650;
}

.node.active {
  border-color: rgba(93, 226, 190, .9);
  background: linear-gradient(180deg, #ffffff, #e5fbf5);
  box-shadow: 0 20px 42px rgba(35, 210, 166, .26), 0 0 0 4px rgba(79, 226, 188, .12);
  transform: translateY(-3px);
}

.node.receiving {
  border-color: rgba(111, 167, 232, .95);
  box-shadow: 0 20px 42px rgba(49, 122, 209, .24), 0 0 0 4px rgba(111, 167, 232, .13);
}

.link {
  position: absolute;
  height: 4px;
  border-radius: 999px;
  background: rgba(192, 225, 217, .2);
  transform-origin: left center;
  z-index: 1;
  overflow: hidden;
}

.link.active {
  background: linear-gradient(90deg, rgba(54, 231, 188, .1), rgba(54, 231, 188, .95), rgba(85, 153, 229, .9));
  box-shadow: 0 0 18px rgba(54, 231, 188, .42);
}

.link.active::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, .9), transparent);
  animation: routePulse 1.4s ease-in-out infinite;
}

.packet {
  position: absolute;
  width: max-content;
  min-width: 84px;
  min-height: 40px;
  display: inline-grid;
  grid-template-columns: 12px auto;
  align-items: center;
  gap: .45rem;
  padding: .3rem .5rem;
  border: 1px solid rgba(255, 255, 255, .32);
  border-radius: 999px;
  background: linear-gradient(135deg, #22b889, #1d5f9f);
  color: #fff;
  font-size: .78rem;
  font-weight: 850;
  box-shadow: 0 18px 40px rgba(0, 0, 0, .28), 0 0 24px rgba(45, 217, 174, .34);
  transform: translate(var(--packet-x, 0), var(--packet-y, 0));
  transition: transform .72s cubic-bezier(.2, .72, .15, 1), opacity .25s ease;
  z-index: 5;
  white-space: nowrap;
}

.packet::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 999px;
  background: #d9fff4;
  box-shadow: 0 0 12px rgba(217, 255, 244, .9);
}

.packet.idle {
  opacity: .38;
}

.packet.arrived {
  animation: packetArrive .42s ease-out;
}

.step-strip {
  position: absolute;
  left: var(--space-4);
  right: var(--space-4);
  bottom: var(--space-3);
  display: grid;
  grid-template-columns: repeat(var(--step-count), minmax(0, 1fr));
  gap: .35rem;
  z-index: 6;
}

.step-dot {
  height: 5px;
  border-radius: 999px;
  background: rgba(224, 243, 238, .22);
}

.step-dot.done {
  background: rgba(54, 231, 188, .95);
  box-shadow: 0 0 12px rgba(54, 231, 188, .35);
}

.step-dot.current {
  background: #fff;
  box-shadow: 0 0 14px rgba(255, 255, 255, .5);
}

.visualizer-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: start;
  gap: var(--space-3);
  padding: var(--space-3);
  border-bottom: 1px solid rgba(255, 255, 255, .1);
  background: linear-gradient(180deg, #0b2734, #09212d);
  color: #eefaf7;
  min-width: 0;
}

.step-meta {
  display: grid;
  gap: .35rem;
}

.step-counter {
  color: #7ee4c9;
  font-weight: 850;
  font-size: .88rem;
}

.step-title {
  font-weight: 850;
  font-size: 1.15rem;
}

.visualizer-panel .muted {
  color: rgba(238, 250, 247, .78);
  overflow-wrap: anywhere;
}

.visualizer-panel-actions {
  display: grid;
  gap: .75rem;
  min-width: min(360px, 100%);
  max-width: 100%;
}

.visualizer-panel .control-button.primary {
  border-color: rgba(126, 228, 201, .62);
  background: rgba(126, 228, 201, .18);
}

.visualizer-step-list {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: repeat(var(--step-count, 5), minmax(0, 1fr));
  gap: .4rem;
  min-width: 0;
}

.visualizer-step-button {
  display: grid;
  gap: .08rem;
  min-width: 0;
  min-height: 46px;
  padding: .45rem .5rem;
  border: 1px solid rgba(213, 239, 233, .14);
  border-radius: 7px;
  background: rgba(255, 255, 255, .055);
  color: rgba(238, 250, 247, .72);
  text-align: left;
  cursor: pointer;
}

.visualizer-step-button:hover {
  border-color: rgba(126, 228, 201, .5);
  color: #fff;
  background: rgba(126, 228, 201, .1);
}

.visualizer-step-button[aria-current="step"] {
  border-color: rgba(126, 228, 201, .85);
  background: rgba(126, 228, 201, .16);
  color: #fff;
}

.visualizer-step-button.done {
  color: rgba(238, 250, 247, .9);
}

.visualizer-step-button strong {
  font-size: .72rem;
  line-height: 1;
}

.visualizer-step-button span {
  overflow: hidden;
  color: inherit;
  font-size: .74rem;
  font-weight: 750;
  line-height: 1.25;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.visualizer-trace {
  display: grid;
  grid-template-rows: auto 1fr;
  gap: .85rem;
  padding: var(--space-3);
  min-width: 0;
  border-left: 1px solid rgba(255, 255, 255, .1);
  background:
    radial-gradient(circle at 80% 18%, rgba(111, 167, 232, .16), transparent 28%),
    #071f2b;
}

.visualizer-trace-header {
  display: grid;
  gap: .2rem;
  padding-bottom: .85rem;
  border-bottom: 1px solid rgba(255, 255, 255, .1);
  color: #eefaf7;
}

.visualizer-trace-header span {
  color: rgba(126, 228, 201, .72);
  font-size: .72rem;
  font-weight: 900;
  letter-spacing: .08em;
}

.visualizer-trace-header strong {
  font-size: 1rem;
  line-height: 1.35;
}

.visualizer-terminal {
  margin: 0;
  min-width: 0;
  min-height: 0;
  border: 1px solid rgba(255, 255, 255, .12);
  border-radius: 12px;
  padding: var(--space-3);
  overflow: auto;
  background: #04131b;
  color: #bdfbe8;
  font: 700 .86rem/1.7 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  white-space: pre-wrap;
}

.visualizer-terminal .dim {
  color: rgba(189, 251, 232, .62);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}

.control-button {
  min-height: 42px;
  border: 1px solid rgba(213, 239, 233, .18);
  border-radius: 7px;
  background: rgba(255, 255, 255, .08);
  color: #eefaf7;
  padding: .5rem .75rem;
  font-weight: 750;
  cursor: pointer;
}

.control-button:hover:not(:disabled) {
  border-color: rgba(126, 228, 201, .75);
  color: #fff;
  background: rgba(126, 228, 201, .14);
}

.control-button:disabled {
  opacity: .5;
  cursor: not-allowed;
}

.progress {
  height: 8px;
  border-radius: 999px;
  background: rgba(255, 255, 255, .1);
  overflow: hidden;
}

.progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, #36e7bc, #6fa7e8);
  transition: width .25s ease;
}

@keyframes scan {
  to {
    transform: translateX(100%);
  }
}

@keyframes routePulse {
  from {
    transform: translateX(-100%);
  }
  to {
    transform: translateX(100%);
  }
}

@keyframes packetArrive {
  0% {
    filter: brightness(1);
  }
  45% {
    filter: brightness(1.28);
  }
  100% {
    filter: brightness(1);
  }
}

@keyframes arpDraw {
  from {
    transform: scaleX(.08);
    opacity: .45;
  }
  to {
    transform: scaleX(1);
    opacity: 1;
  }
}

.site-footer {
  border-top: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: var(--space-3);
  flex-wrap: wrap;
  padding: var(--space-4) 0;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
}

@media (max-width: 860px) {
  .header-inner {
    align-items: flex-start;
    flex-direction: column;
    padding: var(--space-2) 0;
  }

  .site-nav {
    width: 100%;
    justify-content: flex-start;
  }

  .site-nav a {
    white-space: normal;
  }

  .hero .section-inner {
    min-height: auto;
  }

  .grid.three,
  .grid.two,
  .animation-app,
  .animation-notes,
  .page-shell {
    grid-template-columns: 1fr;
  }

  .sidebar,
  .animation-browser {
    position: static;
    max-height: none;
  }

  .visualizer-grid {
    grid-template-columns: 1fr;
  }

  .visualizer-static-board {
    grid-template-columns: 1fr;
  }

  .visualizer-panel {
    grid-template-columns: 1fr;
  }

  .visualizer-panel-actions {
    min-width: 0;
  }

  .visualizer-trace {
    border-left: 0;
    border-top: 1px solid rgba(255, 255, 255, .1);
  }

  .visualizer-stage {
    padding: var(--space-3);
    min-height: 320px;
  }

  .network-map {
    min-height: 272px;
  }

  .node {
    width: 112px;
    min-height: 76px;
    font-size: .82rem;
  }
}

@media (max-width: 560px) {
  .header-inner,
  .footer-inner,
  .section-inner,
  .page-shell {
    width: min(100% - 24px, 1120px);
  }

  .site-nav a {
    padding: .4rem .5rem;
  }

  .site-nav {
    display: grid;
    grid-template-columns: 1fr;
  }

  .site-nav a {
    text-align: center;
    min-width: 0;
    overflow-wrap: anywhere;
    line-height: 1.25;
    padding: .5rem .4rem;
  }

  .article-header h1,
  .animation-topic-header h2 {
    max-width: 100%;
    font-size: 1.72rem;
    word-break: break-all;
  }

  .article-header p,
  .animation-intro p,
  .animation-topic-header p {
    word-break: break-all;
  }

  .animation-mode-summary {
    grid-template-columns: 1fr;
  }

  .animation-kind-stat {
    min-height: 46px;
    grid-template-columns: auto minmax(0, 1fr);
    align-items: center;
  }

  .animation-tabs {
    display: grid;
    grid-template-columns: 1fr;
  }

  .animation-tab {
    width: 100%;
  }

  .curriculum-grid {
    grid-template-columns: 1fr;
  }

  .coverage-summary {
    grid-template-columns: 1fr;
  }

  .coverage-summary a {
    grid-template-columns: auto minmax(0, 1fr) auto;
  }

  .domain-detail summary {
    align-items: flex-start;
  }

  .objective {
    grid-template-columns: 1fr;
    gap: .65rem;
  }

  .objective-code {
    justify-content: flex-start;
    width: fit-content;
    padding: 0 .75rem;
  }

  .hero-actions,
  .button-row {
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .visualizer-panel {
    gap: .85rem;
    padding: .85rem;
  }

  .visualizer-panel .controls {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: .35rem;
    min-width: 0;
    max-width: 100%;
  }

  .visualizer-panel .control-button {
    min-width: 0;
    min-height: 40px;
    padding: .42rem .3rem;
    width: 100%;
  }

  .visualizer-panel .muted {
    display: -webkit-box;
    overflow: hidden;
    -webkit-box-orient: vertical;
    -webkit-line-clamp: 2;
  }

  .visualizer-step-list {
    gap: .3rem;
  }

  .visualizer-step-button {
    place-items: center;
    min-height: 38px;
    padding: .35rem .2rem;
    text-align: center;
  }

  .visualizer-step-button span {
    display: none;
  }

  .visualizer-stage {
    min-height: 270px;
    padding: .75rem;
  }

  .visualizer-sequence {
    padding: 0;
  }

  .visualizer-lanes {
    gap: .25rem;
    padding: .75rem .5rem .6rem;
  }

  .visualizer-lane span {
    width: 100%;
    min-height: 34px;
    padding: .28rem .25rem;
    font-size: .66rem;
  }

  .visualizer-lane small {
    font-size: .56rem;
  }

  .visualizer-sequence-stage {
    min-height: 238px;
  }

  .visualizer-event::before {
    top: -30px;
    max-width: 96px;
    font-size: .68rem;
  }

  .network-map {
    min-height: 238px;
  }

  .visualizer-trace {
    min-height: 220px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
    animation-duration: .01ms !important;
  }
}

@media (prefers-reduced-motion: reduce) {
  .network-map::after,
  .link.active::after,
  .packet.arrived,
  .visualizer-event.active {
    animation: none;
  }
}