:root {
  --green: #76b900;
  --ink: #202523;
  --muted: #66716c;
  --line: #e1e6e2;
  --soft: #f5f7f4;
  --header: 70px;
}
* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  scroll-padding-top: 100px;
}
body {
  margin: 0;
  color: var(--ink);
  font-family: Inter, "Noto Sans SC", "Microsoft Yahei", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.85;
  background: white;
}
a {
  color: #487800;
  text-underline-offset: 4px;
}
button,
input,
select {
  font: inherit;
}
button {
  cursor: pointer;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
summary:focus-visible {
  outline: 3px solid #76b900;
  outline-offset: 4px;
}
.skip {
  position: fixed;
  left: 20px;
  top: -80px;
  z-index: 10;
  background: white;
  padding: 10px;
}
.skip:focus {
  top: 10px;
}
header {
  height: var(--header);
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
  background: #fffffffa;
  backdrop-filter: blur(10px);
  padding: 0 32px;
  gap: 20px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 22px;
  text-decoration: none;
  color: var(--ink);
  white-space: nowrap;
}
.brand-mark {
  color: #192015;
  font-size: 21px;
  font-weight: 850;
  letter-spacing: -1px;
  border-left: 7px solid var(--green);
  padding-left: 10px;
}
.brand-course {
  border-left: 1px solid #ccd2cd;
  padding-left: 22px;
  font-size: 17px;
}
.brand-course b {
  font-weight: 400;
  color: var(--muted);
}
.header-actions {
  display: flex;
  align-items: center;
  gap: 24px;
  font-size: 14px;
}
.header-actions a {
  text-decoration: none;
  color: var(--ink);
}
.search-open {
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--soft);
  padding: 4px 14px;
  min-width: 165px;
  text-align: left;
  color: var(--muted);
}
kbd {
  float: right;
  margin-left: 30px;
  color: #919991;
}
.menu-toggle {
  display: none;
  border: 0;
  background: transparent;
  font-size: 22px;
}
.layout {
  display: grid;
  grid-template-columns: 260px minmax(0, 850px) 180px;
  max-width: 1440px;
  margin: auto;
}
.sidebar {
  height: calc(100vh - var(--header));
  position: sticky;
  top: var(--header);
  overflow: auto;
  border-right: 1px solid var(--line);
  padding: 30px 20px 24px;
}
.sidebar-intro {
  font-weight: 650;
  font-size: 15px;
  line-height: 1.6;
  margin-bottom: 24px;
}
.nav-group {
  font-size: 11px;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  font-weight: 700;
  color: #6c756d;
  margin: 23px 12px 7px;
}
.sidebar a {
  display: flex;
  align-items: baseline;
  gap: 8px;
  color: #58625b;
  text-decoration: none;
  font-size: 13px;
  line-height: 1.6;
  padding: 8px 10px;
  border-radius: 4px;
  margin: 2px 0;
}
.sidebar a:hover {
  background: #f4f6f2;
}
.sidebar a[aria-current] {
  background: #edf5e3;
  color: #315a00;
  font-weight: 650;
  border-left: 3px solid var(--green);
  padding-left: 7px;
}
.nav-number {
  font-size: 11px;
  color: #80897e;
  flex-shrink: 0;
  min-width: 13px;
}
.nav-number:empty {
  display: none;
}
main {
  min-width: 0;
  padding: 40px 54px 24px;
}
.breadcrumb {
  color: #7d867e;
  font-size: 12px;
  margin-bottom: 22px;
}
.breadcrumb span {
  margin: 0 10px;
  color: #a7afa7;
}
.eyebrow {
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.16em;
  color: #65853f;
  margin: 0 0 12px;
}
.lesson-heading {
  padding: 12px 0 30px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 30px;
}
.lesson-heading h1 {
  font-size: 38px;
  line-height: 1.28;
  letter-spacing: -0.035em;
  font-weight: 720;
  margin: 0 0 22px;
}
.lead {
  font-size: 18px;
  line-height: 1.8;
  color: #657067;
  margin: 0;
  max-width: 42em;
}
.lesson-meta {
  font-size: 12px;
  margin-top: 24px;
  color: #798275;
}
.is-home {
  position: relative;
}
.hero-image {
  margin: 20px -10px -10px;
}
.hero-image img {
  width: 100%;
  height: 300px;
  object-fit: contain;
}
.toc {
  position: sticky;
  top: var(--header);
  align-self: start;
  padding: 45px 15px 20px;
  max-height: calc(100vh - 70px);
  overflow: auto;
  font-size: 11px;
}
.toc p {
  font-weight: 700;
  color: #545e54;
  margin: 0 0 14px;
}
.toc a {
  display: block;
  color: #788076;
  text-decoration: none;
  line-height: 1.6;
  padding: 7px 0 7px 12px;
  border-left: 1px solid var(--line);
}
.toc a.active {
  color: #487700;
  border-left: 2px solid #76b900;
}
section {
  margin: 38px 0 44px;
}
h2 {
  font-size: 25px;
  letter-spacing: -0.025em;
  line-height: 1.45;
  margin: 0 0 20px;
  font-weight: 650;
}
h3 {
  font-size: 18px;
  line-height: 1.55;
  font-weight: 650;
  margin: 28px 0 12px;
}
p {
  margin: 0 0 18px;
}
ul,
ol {
  padding-left: 24px;
  margin: 16px 0 22px;
}
li {
  margin: 6px 0;
}
strong {
  font-weight: 650;
}
p code,
li code,
td code {
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.84em;
  padding: 2px 5px;
  background: #f1f3f0;
  border-radius: 3px;
  overflow-wrap: anywhere;
}
.note {
  border-left: 3px solid #76b900;
  background: #f4f8ef;
  padding: 17px 22px;
  margin: 24px 0;
  font-size: 14px;
}
.note > strong {
  display: block;
  margin-bottom: 6px;
}
.note p {
  margin: 0;
}
.code-block {
  margin: 24px 0;
  border-radius: 6px;
  overflow: hidden;
  border: 1px solid #26302c;
  background: #17201c;
  color: #e3eddf;
}
.code-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 16px;
  border-bottom: 1px solid #354037;
  font-size: 11px;
  color: #b4c5b7;
  letter-spacing: 0.04em;
}
.copy {
  border: 1px solid #50604f;
  border-radius: 3px;
  padding: 2px 10px;
  background: #253128;
  color: #deecd7;
  font-size: 11px;
}
.copy:hover {
  background: #3a4b32;
}
pre {
  margin: 0;
  padding: 20px;
  overflow: auto;
  font-size: 12px;
  line-height: 1.85;
  tab-size: 2;
}
code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}
.table-scroll {
  overflow: auto;
  margin: 24px 0;
}
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  line-height: 1.65;
}
th {
  text-align: left;
  background: var(--soft);
  font-weight: 600;
}
th,
td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
td:first-child {
  white-space: nowrap;
}
.quiz {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 8px 0 20px;
  margin: 28px 0;
}
.quiz h3 {
  font-size: 14px;
  color: #557f2a;
}
.quiz p {
  font-size: 15px;
}
.quiz details {
  font-size: 14px;
  background: var(--soft);
  padding: 12px 16px;
  border-radius: 4px;
}
.quiz details p {
  font-size: 14px;
  margin: 15px 0 0;
}
summary {
  cursor: pointer;
}
.pipeline {
  display: flex;
  gap: 10px;
  padding: 0;
  list-style: none;
  margin: 28px 0;
  flex-wrap: wrap;
}
.pipeline li {
  flex: 1;
  min-width: 95px;
  font-size: 12px;
  background: #f4f7ef;
  padding: 14px;
  border-bottom: 2px solid #b7cd98;
  margin: 0;
}
.pipeline span {
  display: block;
  font-family: monospace;
  font-size: 11px;
  color: #71903c;
  margin-bottom: 7px;
}
.media {
  margin: 26px 0;
}
.motion {
  position: relative;
  background: #18211b;
  border-radius: 6px;
  overflow: hidden;
  line-height: 0;
}
.motion img {
  width: 100%;
  height: auto;
  aspect-ratio: 16/9;
  object-fit: contain;
}
.play-motion {
  position: absolute;
  bottom: 14px;
  left: 16px;
  border: 1px solid #8da882;
  background: #192b19e8;
  color: white;
  font-size: 12px;
  border-radius: 4px;
  padding: 8px 16px;
  line-height: 1.5;
}
figcaption {
  font-size: 12px;
  line-height: 1.6;
  color: #7e867c;
  margin-top: 11px;
}
.references {
  font-size: 13px;
}
.references li {
  margin: 12px 0;
}
.pager {
  display: flex;
  justify-content: space-between;
  gap: 30px;
  margin-top: 45px;
  padding: 27px 0;
  border-top: 1px solid var(--line);
  font-size: 14px;
}
.pager a {
  flex: 1;
  text-decoration: none;
  color: #3e552a;
}
.pager a:last-child {
  text-align: right;
}
.pager small {
  display: block;
  font-size: 10px;
  color: #8a9385;
  margin-bottom: 7px;
}
footer {
  font-size: 10px;
  color: #98a092;
  border-top: 1px solid var(--line);
  padding-top: 22px;
}
footer a {
  color: inherit;
}
footer span {
  display: block;
  margin-top: 6px;
}
.anatomy {
  border: 1px solid var(--line);
  border-radius: 7px;
  overflow: hidden;
  margin: 24px 0;
}
.viewer-stage {
  height: 430px;
  position: relative;
  background: #f4f5f1;
}
.viewer-stage canvas {
  width: 100%;
  height: 100%;
  display: block;
  touch-action: none;
}
.robot-fallback {
  height: 100%;
  width: 100%;
  object-fit: contain;
}
.load-robot {
  position: absolute;
  bottom: 18px;
  left: 50%;
  transform: translateX(-50%);
  background: #23401b;
  color: white;
  border: 0;
  border-radius: 4px;
  padding: 9px 20px;
  font-size: 13px;
  white-space: nowrap;
}
.viewer-status {
  position: absolute;
  top: 12px;
  left: 14px;
  font-size: 11px;
  color: #6b7861;
  max-width: 80%;
  z-index: 1;
}
.viewer-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 14px;
  padding: 14px 20px;
  background: #f8faf5;
  border-top: 1px solid var(--line);
  font-size: 12px;
}
.viewer-toolbar label {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 1;
}
.viewer-toolbar input {
  flex: 1;
  min-width: 60px;
  accent-color: var(--green);
}
.view-reset,
.view-focus {
  border: 1px solid #cbd7c0;
  background: white;
  border-radius: 3px;
  padding: 3px 10px;
  font-size: 11px;
}
.component-info {
  padding: 18px 20px;
  font-size: 13px;
  min-height: 115px;
}
.component-info p {
  font-size: 12px;
  color: var(--muted);
  margin: 5px 0 0;
}
.component-label {
  display: block;
  font-size: 12px;
  padding: 0 20px 18px;
}
.component-select {
  font-size: 12px;
  width: 100%;
  margin-top: 6px;
  padding: 6px;
  border: 1px solid #ccd5c7;
  background: white;
}
.search-dialog {
  border: 1px solid var(--line);
  border-radius: 10px;
  width: min(650px, 95vw);
  padding: 24px;
  top: 12vh;
  max-height: 70vh;
  margin-top: 0;
  box-shadow: 0 20px 80px #0003;
}
.search-dialog::backdrop {
  background: #16241688;
  backdrop-filter: blur(3px);
}
.search-dialog form {
  display: flex;
  justify-content: space-between;
  font-size: 14px;
  font-weight: 650;
}
.search-dialog form button {
  border: 0;
  background: none;
  font-size: 23px;
}
.search-dialog input {
  width: 100%;
  padding: 12px;
  margin: 18px 0;
  border: 1px solid #aaba9b;
  border-radius: 4px;
}
.search-results a {
  display: block;
  padding: 12px 5px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  font-size: 14px;
}
.search-results small {
  display: block;
  font-size: 11px;
  color: var(--muted);
}
@media (min-width: 1500px) {
  main {
    padding-left: 65px;
    padding-right: 65px;
  }
}
@media (max-width: 1150px) {
  .layout {
    grid-template-columns: 235px minmax(0, 1fr);
  }
  .toc {
    display: none;
  }
  main {
    padding: 32px 42px;
  }
  .sidebar {
    padding-left: 14px;
    padding-right: 14px;
  }
  .header-actions {
    gap: 15px;
  }
}
@media (max-width: 760px) {
  :root {
    --header: 60px;
  }
  body {
    font-size: 15px;
  }
  .layout {
    display: block;
  }
  header {
    padding: 0 15px;
    gap: 12px;
  }
  .menu-toggle {
    display: block;
  }
  .brand {
    gap: 0;
  }
  .brand-mark {
    display: none;
  }
  .brand-course {
    border: 0;
    padding: 0;
    font-size: 16px;
  }
  .brand-course b {
    display: none;
  }
  .header-actions {
    margin-left: auto;
    gap: 14px;
  }
  .search-open {
    min-width: 0;
    background: transparent;
    border: 0;
    font-size: 0;
    padding: 0;
  }
  .search-open:before {
    content: "⌕";
    font-size: 25px;
  }
  .search-open kbd,
  .repo-link {
    display: none;
  }
  .language {
    font-size: 12px;
  }
  .sidebar {
    display: none;
    position: fixed;
    z-index: 4;
    width: 290px;
    background: white;
    box-shadow: 20px 20px 50px #1b291a33;
    top: 60px;
  }
  .sidebar.open {
    display: block;
  }
  main {
    padding: 25px 22px;
  }
  .lesson-heading h1 {
    font-size: 31px;
  }
  .lead {
    font-size: 16px;
  }
  .eyebrow {
    font-size: 10px;
  }
  .breadcrumb {
    font-size: 10px;
  }
  .hero-image img {
    height: 250px;
  }
  h2 {
    font-size: 22px;
  }
  .viewer-stage {
    height: 340px;
  }
  pre {
    font-size: 11px;
    padding: 16px;
  }
  .table-scroll {
    max-width: 100%;
  }
  th,
  td {
    padding: 10px;
  }
  .note {
    padding: 14px 16px;
  }
  .pipeline {
    gap: 6px;
  }
  .pipeline li {
    min-width: 90px;
  }
  .pager {
    font-size: 12px;
    gap: 20px;
  }
}
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  * {
    transition: none !important;
  }
}

.viewer-toolbar {
  flex-wrap: wrap;
}
.viewer-toolbar label {
  min-width: 180px;
}
.view-focus:disabled {
  opacity: 0.45;
  cursor: default;
}
/* Student reading and interactive teaching, revision 2. */
.language-menu {
  position: relative;
  line-height: 1;
}
.language-menu > summary {
  list-style: none;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 5px;
}
.language-menu > summary::-webkit-details-marker {
  display: none;
}
.language-menu > summary:hover {
  background: var(--soft);
}
.language-options {
  position: absolute;
  right: 0;
  top: 46px;
  padding: 7px;
  background: white;
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: 0 8px 24px #1522191a;
  min-width: 145px;
  line-height: 1.8;
}
.language-options a {
  display: block;
  padding: 7px 12px;
  border-radius: 4px;
}
.language-options a[aria-current] {
  background: #edf5e3;
  color: #315a00;
}
.language-options a:hover {
  background: var(--soft);
}
.media video {
  display: block;
  width: 100%;
  height: auto;
  max-height: 680px;
  border-radius: 6px;
  background: #17212b;
}
.media .still-link {
  display: block;
  cursor: zoom-in;
}
.media img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 6px;
}
.media figcaption {
  color: #5c685f;
}
.viewer-stage {
  height: 510px;
  background: #35414d;
}
.viewer-status {
  color: #e2eaf0;
  background: #27313dc9;
  padding: 4px 8px;
  border-radius: 4px;
  pointer-events: none;
  z-index: 2;
}
.viewer-stage canvas {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.part-labels {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 1;
  overflow: hidden;
}
.part-labels svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
}
.part-labels path {
  stroke: #c5dfaf;
  stroke-width: 1;
  fill: none;
  opacity: 0.8;
}
.part-label {
  position: absolute;
  pointer-events: auto;
  color: #f4f8ee;
  border: 1px solid #789565;
  background: #26352ef2;
  border-radius: 4px;
  padding: 4px 8px;
  line-height: 20px;
  font-size: 11px;
  white-space: nowrap;
}
.part-label:hover,
.part-label:focus-visible {
  background: #46652e;
  border-color: #a8d471;
}
.part-label[hidden] {
  display: none;
}
.component-info {
  min-height: 110px;
}
.viewer-toolbar label {
  min-width: 150px;
}
.hero-image img {
  object-fit: cover;
  height: auto;
  border-radius: 8px;
}
.robot-fallback {
  object-fit: cover;
}
.formula {
  border-left: 3px solid #91b75d;
  padding: 10px 18px;
  background: #f7f9f4;
  margin: 24px 0;
  overflow-x: auto;
}
.formula .katex-display {
  margin: 10px 0;
  text-align: left;
}
.formula-label {
  font-size: 12px;
  color: #527235;
  font-weight: 600;
}
.katex {
  font-size: 1.06em;
}
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0;
}
.concept-figure {
  margin: 28px 0;
  padding: 22px;
  background: #f6f8f5;
  border: 1px solid #dfe6dc;
  border-radius: 7px;
}
.concept-figure svg {
  width: 100%;
  height: auto;
  display: block;
}
.diagram-caption {
  font-size: 13px;
  color: #566651;
  line-height: 1.7;
  margin: 12px 0 0;
}
.concept-controls {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  align-items: center;
  font-size: 13px;
  margin: 16px 0 8px;
}
.concept-controls label {
  display: flex;
  align-items: center;
  gap: 9px;
}
.concept-controls input {
  max-width: 150px;
  accent-color: #76b900;
}
.concept-controls select {
  font-size: 13px;
  border: 1px solid #b4c5aa;
  padding: 5px;
  background: white;
}
.navigation-svg {
  min-width: 560px;
  font-size: 16px;
}
.navigation-controls {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}
@media (max-width: 600px) {
  .navigation-controls {
    grid-template-columns: 1fr;
  }
}
.navigation-controls label {
  flex-direction: column;
  align-items: stretch;
}
.navigation-controls input {
  width: 100%;
  max-width: none;
}
.navigation-legend {
  font-size: 13px;
  color: #57606a;
}
.concept-output {
  min-height: 2em;
  font-size: 13px;
  color: #43543a;
}
.diagram-flow {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px 20px;
  margin: 12px 0 8px;
}
.diagram-node {
  position: relative;
  border: 1px solid #aebda5;
  border-radius: 5px;
  padding: 17px 14px;
  background: white;
  font-size: 14px;
  text-align: center;
  line-height: 1.65;
}
.diagram-node small {
  display: block;
  color: #657660;
  font-size: 12px;
  margin-top: 5px;
}
.diagram-node:not(:last-child):after {
  content: "→";
  position: absolute;
  right: -17px;
  top: 30%;
  color: #648245;
}
.diagram-node:nth-child(3n):after {
  content: "↓";
  right: 48%;
  top: 100%;
}
.diagram-node strong {
  display: block;
}
.source-note {
  font-size: 12px;
  color: #63725e;
}
.lesson-heading {
  padding-bottom: 26px;
}
main section {
  margin-bottom: 52px;
}
p {
  line-height: 1.9;
}
.code-block pre {
  font-size: 12px;
}
.image-dialog {
  border: 0;
  border-radius: 8px;
  max-width: 96vw;
  width: 1600px;
  max-height: 95vh;
  padding: 40px 12px 12px;
  background: #26313c;
}
.image-dialog::backdrop {
  background: #0d1419e6;
}
.image-dialog img {
  display: block;
  width: 100%;
  height: auto;
}
.image-dialog button {
  position: absolute;
  right: 12px;
  top: 7px;
  background: none;
  border: 0;
  color: white;
  font-size: 22px;
}
.load-robot {
  z-index: 2;
}
.motion {
  display: none;
}
@media (max-width: 760px) {
  .viewer-stage {
    height: 460px;
  }
  .part-label {
    font-size: 10px;
    padding: 3px 5px;
  }
  .viewer-toolbar {
    padding: 12px;
  }
  .concept-figure {
    padding: 14px 10px;
  }
  .diagram-flow {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  .diagram-node:not(:last-child):after {
    content: "↓";
    right: 48%;
    top: 100%;
  }
  .formula {
    padding: 8px 12px;
  }
  .hero-image img {
    height: auto;
  }
  .concept-controls {
    gap: 10px;
  }
  .component-info {
    padding: 15px;
  }
  .lesson-heading h1 {
    font-size: 29px;
  }
}
.diagram-node:last-child:after {
  display: none;
}
@media (min-width: 761px) {
  .flow-six .diagram-node:nth-child(4) {
    grid-column: 3;
    grid-row: 2;
  }
  .flow-six .diagram-node:nth-child(5) {
    grid-column: 2;
    grid-row: 2;
  }
  .flow-six .diagram-node:nth-child(6) {
    grid-column: 1;
    grid-row: 2;
  }
  .flow-six .diagram-node:nth-child(4):after,
  .flow-six .diagram-node:nth-child(5):after {
    content: "←";
    right: auto;
    left: -17px;
    top: 30%;
  }
}
@media (max-width: 760px) {
  [data-diagram="ppo"] svg text {
    font-size: 21px;
  }
  [data-diagram="ppo"] svg text:last-of-type {
    font-size: 21px;
  }
}
.pose-sequence {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}
.pose-sequence p {
  font-size: 12px;
  margin: 5px 0;
  text-align: center;
  color: #4d6542;
}
.pose-sequence img {
  aspect-ratio: 16/9;
  object-fit: cover;
}
@media (max-width: 760px) {
  .pose-sequence {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .pose-sequence p {
    font-size: 13px;
  }
}

/* Local typefaces and reference-course code styling. */
@font-face {
  font-family: "Open Sans";
  src: url("fonts/OpenSans.woff2") format("woff2");
  font-weight: 300 800;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Noto Sans SC";
  src: url("fonts/NotoSansSC.woff2") format("woff2");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
:root {
  --course-font: "Open Sans", "Noto Sans SC", sans-serif;
}
body,
button,
input,
select,
textarea {
  font-family: var(--course-font);
}
.brand-course {
  font-size: 18px;
}
.brand-course b {
  font-weight: 500;
}
.code-block {
  background: #0d1117;
  border: 1px solid #30363d;
  border-radius: 8px;
  overflow: hidden;
  margin: 24px 0;
}
.code-block .code-toolbar {
  background: #161b22;
  color: #c9d1d9;
  border-bottom: 1px solid #30363d;
  font-size: 12px;
  padding: 11px 16px;
  gap: 14px;
  align-items: center;
}
.code-block .source-link {
  color: #a5d6ff;
  text-decoration: none;
  white-space: nowrap;
  font-size: 12px;
}
.source-link:hover {
  text-decoration: underline;
}
.code-block .copy {
  color: #e6edf3;
  background: #21262d;
  border: 1px solid #484f58;
  border-radius: 5px;
  padding: 4px 10px;
}
.code-block pre {
  background: #0d1117;
  color: #e6edf3;
  margin: 0;
  padding: 0;
  font-size: 13px;
  line-height: 1.75;
  overflow: auto;
}
.code-block pre code.hljs {
  display: block;
  padding: 20px 22px;
  background: #0d1117;
  color: #e6edf3;
  font-family:
    ui-monospace, SFMono-Regular, Consolas, "Liberation Mono", monospace;
  font-size: inherit;
}
.diagram-scroll {
  overflow-x: auto;
  overscroll-behavior-inline: contain;
  padding: 2px;
}
.concept-figure .architecture-svg {
  display: block;
  width: 100%;
  min-width: 620px;
  height: auto;
  font-family: var(--course-font);
}
.concept-figure {
  background: #fff;
  border: 1px solid #d0d7de;
  border-radius: 8px;
  padding: 20px;
}
.concept-figure svg {
  font-family: var(--course-font);
}
.diagram-caption {
  color: #57606a;
  font-size: 13px;
  line-height: 1.8;
  margin-top: 14px;
}
@media (max-width: 760px) {
  .code-block pre {
    font-size: 12px;
  }
  .code-block pre code.hljs {
    padding: 16px;
  }
  .concept-figure {
    padding: 14px 10px;
  }
  .code-toolbar > span {
    min-width: 0;
    overflow-wrap: anywhere;
  }
  .brand-course {
    font-size: 15px;
  }
}

.brand-course {
  border-left: 0;
  padding-left: 0;
}
.diagram-scroll-hint {
  display: none;
}
@media (max-width: 760px) {
  .diagram-scroll-hint {
    display: block;
    color: #57606a;
    font-size: 12px;
    margin: 0 0 8px;
  }
}

/* Progressive 3D loading: expose controls only when a model is ready. */
.anatomy:not([data-loaded="true"]) .viewer-toolbar {
  display: none;
}
.load-robot {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 22px;
  border: 1px solid #a8bcce;
  border-radius: 10px;
  background: #243342;
  color: #fff;
  box-shadow: 0 8px 25px #10213040;
  font:
    600 16px "Open Sans",
    "Noto Sans SC",
    sans-serif;
  cursor: pointer;
}
.load-robot::before {
  content: "◇";
  font-size: 27px;
  font-weight: 400;
  color: #c4e69b;
}
.load-robot:hover {
  background: #34495c;
  border-color: #c4e69b;
}

/* Disclosure controls have the same full-row pointer and keyboard target. */
.quiz details > summary,
.enrichment > summary {
  display: list-item;
  width: 100%;
  box-sizing: border-box;
  padding: 14px 18px;
  cursor: pointer;
  color: #355d12;
  background: #edf4e7;
  border-radius: 5px;
  font-weight: 600;
  font-size: 14px;
}
.quiz details > summary:hover,
.enrichment > summary:hover {
  background: #e2edd8;
}
.quiz details > summary:focus-visible,
.enrichment > summary:focus-visible {
  outline: 2px solid #467b20;
  outline-offset: 3px;
}
.quiz details > p {
  padding: 0 18px;
}
.enrichment {
  margin: 24px 0;
  border: 1px solid #dce5d5;
  border-radius: 6px;
}
.enrichment-body {
  padding: 5px 20px 16px;
}
.enrichment-body > p {
  font-size: 14px;
}
.network-svg {
  min-width: 620px;
}
.network-figure figcaption {
  font-size: 13px;
  color: #566651;
}
.anatomy[data-loaded="true"] .viewer-stage {
  height: 560px;
}
.part-label {
  font-size: 11px;
  padding: 3px 6px;
}
@media (max-width: 760px) {
  .anatomy[data-loaded="true"] .viewer-stage {
    height: 540px;
  }
  .part-label {
    font-size: 10px;
    padding: 2px 4px;
  }
  .enrichment-body {
    padding: 2px 12px 12px;
  }
}

.video-stage-caption {
  padding: 13px 16px;
  background: #eaf0f4;
  border-left: 3px solid #76b900;
  border-radius: 0 0 5px 5px;
  font-size: 13px;
  line-height: 1.7;
}
.video-stage-caption strong,
.video-stage-caption span {
  display: block;
}
.video-stage-caption strong {
  color: #264b63;
  margin-bottom: 3px;
}

/* Evaluation design counter; no simulation is started. */
.scenario-matrix { margin: 1.5rem 0; padding: 1.25rem; border: 1px solid var(--line, #bcc9ce); border-radius: 12px; }
.matrix-options { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: .8rem; margin: 1rem 0; }
.matrix-options label { display: flex; align-items: center; gap: .5rem; }
.matrix-seeds { width: 5rem; padding: .4rem; font: inherit; }
.matrix-output { font-weight: 700; }
.matrix-scope { font-size: .9em; }

.architecture-svg.flow-mobile { display: none; }
@media (max-width: 600px) {
  .architecture-svg.flow-desktop { display: none; }
  .architecture-svg.flow-mobile { display: block; min-width: 0; }
}