:root {
  color-scheme: light;
  --ink: #17202a;
  --text: #344252;
  --muted: #66788a;
  --line: #d8e0e8;
  --soft: #f4f7fa;
  --panel: #ffffff;
  --blue: #1f6feb;
  --blue-soft: #edf5ff;
  --green: #11845b;
  --green-soft: #effcf6;
  --cyan-soft: #ecfeff;
  --yellow-soft: #fffbea;
  --red: #c23b3b;
  --shadow: 0 18px 42px rgba(23, 32, 42, 0.1);
  --radius: 8px;
  --max: 1040px;
  --read: 920px;
  --article: 920px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans CJK SC", Arial, sans-serif;
  line-height: 1.7;
  background: linear-gradient(180deg, #f8fbff 0, #fff 520px);
}

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid rgba(216, 224, 232, 0.9);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(16px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
  width: min(100% - 32px, var(--max));
  min-height: 64px;
  margin: 0 auto;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 900;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 31px;
  height: 31px;
  border-radius: 7px;
  color: #fff;
  background: linear-gradient(135deg, #1f6feb, #11845b);
}

.top-nav {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  scrollbar-width: none;
}

.top-nav::-webkit-scrollbar {
  display: none;
}

.top-nav a {
  padding: 8px 10px;
  border-radius: 7px;
  color: #526376;
  font-size: 14px;
  text-decoration: none;
  white-space: nowrap;
}

.top-nav a:hover,
.top-nav a.active {
  color: var(--ink);
  background: var(--soft);
  font-weight: 800;
}

.hero {
  display: grid;
  grid-template-columns: 1fr;
  gap: 34px;
  align-items: start;
  width: min(100% - 32px, var(--article));
  margin: 0 auto;
  padding: 52px 0 46px;
}

.hero-copy {
  width: 100%;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--green);
  font-size: 14px;
  font-weight: 900;
}

h1 {
  max-width: var(--read);
  margin: 0;
  font-size: clamp(30px, 3.8vw, 46px);
  line-height: 1.14;
  letter-spacing: 0;
}

.hero-lead {
  max-width: var(--read);
  margin: 18px 0 0;
  color: #344252;
  font-size: 17px;
  line-height: 1.78;
}

.hero-actions {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  max-width: none;
  margin-top: 26px;
}

.hero-actions a {
  min-height: 54px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.82);
  box-shadow: none;
  font-size: 15px;
  font-weight: 800;
  line-height: 1.35;
  text-decoration: none;
}

.hero-actions a:hover {
  border-color: rgba(31, 111, 235, 0.48);
  box-shadow: var(--shadow);
}

.hero-map {
  display: grid;
  gap: 14px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
  box-shadow: 0 12px 28px rgba(23, 32, 42, 0.08);
}

.map-node {
  padding: 14px 15px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
}

.map-node strong {
  display: block;
  font-size: 15px;
}

.map-node span {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.5;
}

.main-compute {
  border-color: rgba(31, 111, 235, 0.26);
  background: var(--blue-soft);
}

.gateway-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.gateway-node {
  border-color: rgba(17, 132, 91, 0.24);
  background: var(--green-soft);
}

.map-link {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: center;
  color: var(--muted);
  font-size: 12px;
  font-weight: 900;
  text-align: center;
}

.map-link::before,
.map-link::after {
  content: "";
  height: 1px;
  background: var(--line);
}

.edge-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 9px;
}

.edge-grid span {
  padding: 9px 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #f8fafc;
  color: #39485a;
  font-size: 12px;
  font-weight: 800;
  text-align: center;
}

.side-notes {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.side-notes p {
  margin: 0;
  padding: 13px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  color: #455568;
  font-size: 13px;
  line-height: 1.58;
}

.content-shell {
  display: block;
  width: min(100% - 32px, var(--article));
  margin: 0 auto;
  padding: 30px 0 86px;
}

.toc {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  position: static;
  max-height: none;
  overflow: visible;
  margin-bottom: 46px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.86);
}

.toc p {
  flex: 1 0 100%;
  margin: 0 0 4px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 900;
}

.toc a {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 7px 10px;
  border-radius: 7px;
  color: #4b5a6b;
  font-size: 13px;
  line-height: 1.35;
  text-decoration: none;
}

.toc a:hover,
.toc a.active {
  color: var(--ink);
  background: var(--soft);
  font-weight: 800;
}

.article {
  min-width: 0;
  width: 100%;
}

.chapter {
  scroll-margin-top: 86px;
  padding: 54px 0 62px;
  border-top: 1px solid var(--line);
}

.chapter:first-child {
  padding-top: 0;
  border-top: 0;
}

.chapter-head {
  display: flex;
  align-items: center;
  gap: 14px;
  max-width: var(--read);
  margin-bottom: 18px;
}

.chapter-head span {
  display: grid;
  place-items: center;
  min-width: 42px;
  height: 32px;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  color: #526376;
  background: #f8fafc;
  font-size: 13px;
  font-weight: 900;
}

h2 {
  margin: 0;
  font-size: clamp(26px, 3.4vw, 38px);
  line-height: 1.2;
  letter-spacing: 0;
}

h3 {
  margin: 0 0 8px;
  font-size: 19px;
  line-height: 1.35;
  letter-spacing: 0;
}

p {
  max-width: var(--read);
  margin: 0 0 14px;
  color: var(--text);
  font-size: 17px;
}

.lead {
  max-width: var(--read);
  color: #334155;
  font-size: 18px;
  line-height: 1.78;
}

.table-scroll {
  width: 100%;
  margin: 28px 0;
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.plain-table {
  width: 100%;
  min-width: 760px;
  border-collapse: collapse;
}

.plain-table th,
.plain-table td {
  padding: 20px 22px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.plain-table th {
  color: #3c4c5f;
  background: #f4f7fa;
  font-size: 15px;
  font-weight: 900;
}

.plain-table td {
  color: #17202a;
  font-size: 16px;
  line-height: 1.8;
}

.plain-table tr:last-child td {
  border-bottom: 0;
}

.plain-table th:last-child,
.plain-table td:last-child {
  border-right: 0;
}

.protocol-table {
  min-width: 900px;
}

.takeaway {
  max-width: var(--read);
  margin-top: 30px;
  padding: 18px 20px;
  border: 1px solid rgba(31, 111, 235, 0.18);
  border-left: 5px solid rgba(31, 111, 235, 0.72);
  border-radius: var(--radius);
  background: #f6f9ff;
  color: #243246;
  font-size: 16px;
  line-height: 1.72;
}

.takeaway strong {
  color: #1f4f8f;
}

.chapter-terms {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-top: 16px;
  max-width: var(--read);
  color: #526376;
  font-size: 13px;
}

.chapter-terms strong {
  margin-right: 2px;
  color: #405169;
  font-weight: 900;
}

.chapter-terms span {
  padding: 5px 8px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fff;
  font-weight: 800;
}

.compare-diagram,
.split-diagram,
.concept-grid,
.method-grid,
.case-grid,
.compare-mini {
  display: grid;
  gap: 18px;
  margin: 28px 0;
}

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

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

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

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

.compare-diagram > div,
.split-diagram > div,
.concept-grid > div,
.method-grid > div,
.case-grid > div,
.compare-mini > div {
  min-width: 0;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.case-grid ul {
  display: grid;
  gap: 8px;
  margin: 12px 0 0;
  padding-left: 20px;
  color: #344252;
}

.case-flow,
.t1s-visual,
.control-stack {
  display: grid;
  gap: 10px;
}

.case-flow {
  grid-template-columns: repeat(6, minmax(0, 1fr));
}

.case-flow span,
.t1s-visual span,
.control-stack div,
.compare-mini span {
  display: grid;
  place-items: center;
  min-height: 48px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #f8fafc;
  color: #405169;
  font-size: 13px;
  font-weight: 800;
  text-align: center;
}

.deep-module {
  margin: 30px 0;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.deep-module > p:last-child {
  margin-bottom: 0;
}

.can-calc {
  max-width: var(--read);
  margin: 28px 0;
  padding: 20px 22px;
  border: 1px solid rgba(31, 111, 235, 0.18);
  border-radius: var(--radius);
  background: #f6f9ff;
}

.can-calc p:last-child {
  margin-bottom: 0;
}

.compare-diagram ul {
  display: grid;
  gap: 8px;
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
}

.compare-diagram li {
  padding: 8px 10px;
  border-left: 3px solid var(--blue);
  border-radius: 0 7px 7px 0;
  background: #f8fafc;
}

.warning {
  max-width: var(--read);
  margin: 28px 0;
  padding: 18px 20px;
  border-left: 5px solid #d28a00;
  border-radius: 0 var(--radius) var(--radius) 0;
  background: var(--yellow-soft);
  color: #243246;
  font-size: 17px;
  font-weight: 800;
}

.boundary-note {
  max-width: var(--read);
  margin: 28px 0;
  padding: 20px 22px;
  border: 1px solid rgba(210, 138, 0, 0.25);
  border-radius: var(--radius);
  background: var(--yellow-soft);
}

.boundary-note h3 {
  margin-bottom: 12px;
}

.boundary-note ul {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-left: 20px;
  color: #344252;
}

.value-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  align-items: center;
  margin-top: 18px;
  max-width: var(--read);
  padding: 16px;
  border: 1px solid rgba(17, 132, 91, 0.22);
  border-radius: var(--radius);
  background: var(--green-soft);
}

.value-strip strong {
  margin-right: 4px;
  color: #0f5f4b;
}

.value-strip span {
  padding: 6px 9px;
  border: 1px solid rgba(17, 132, 91, 0.18);
  border-radius: 999px;
  background: #fff;
  color: #405169;
  font-size: 13px;
  font-weight: 800;
}

.teaching-figure {
  width: 100%;
  margin: 30px 0;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
  overflow-x: auto;
}

.teaching-figure figcaption,
.figure-title {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  margin-bottom: 18px;
}

.teaching-figure figcaption strong,
.figure-title strong {
  color: var(--ink);
  font-size: 18px;
}

.teaching-figure figcaption span,
.figure-title span {
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

.figure-note {
  margin: 18px 0 0;
  padding-top: 14px;
  border-top: 1px solid var(--line);
  color: #526376;
  font-size: 14px;
  line-height: 1.7;
}

.issue-flow {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 120px minmax(0, 1fr);
  gap: 18px;
  align-items: center;
}

.issue-side {
  display: grid;
  gap: 10px;
  padding: 18px;
  border: 1px solid rgba(31, 111, 235, 0.2);
  border-radius: 7px;
  background: var(--blue-soft);
}

.issue-side h3,
.flow-lane h3,
.access-card h3 {
  margin: 0 0 4px;
}

.issue-side span,
.arch-edge span,
.arch-gateways span,
.chip-row span,
.ec-soft span,
.flow-lane span,
.access-flow span {
  padding: 9px 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  color: #39485a;
  font-size: 13px;
  font-weight: 800;
  text-align: center;
}

.problem-side {
  border-color: rgba(210, 138, 0, 0.28);
  background: var(--yellow-soft);
}

.flow-arrow {
  display: grid;
  place-items: center;
  min-height: 58px;
  border-radius: 7px;
  color: #0f4b5a;
  background: var(--cyan-soft);
  font-size: 14px;
  font-weight: 900;
}

.flow-arrow::after {
  content: "→";
  margin-left: 6px;
}

.queue-visual {
  display: grid;
  gap: 16px;
  width: 100%;
  margin: 28px 0;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
  overflow-x: auto;
}

.queue-row {
  display: grid;
  grid-template-columns: 110px 1fr 110px;
  gap: 16px;
  align-items: center;
  min-width: 680px;
}

.capacity-row {
  display: grid;
  grid-template-columns: 110px minmax(220px, 1fr);
  gap: 12px 16px;
  align-items: center;
  min-width: 680px;
}

.capacity-row em {
  grid-column: 2;
  color: #526376;
  font-size: 13px;
  font-style: normal;
  font-weight: 800;
}

.capacity-track {
  position: relative;
  height: 34px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #f8fafc;
}

.capacity-track.near {
  border-color: rgba(17, 132, 91, 0.34);
}

.capacity-track.overflow {
  border-color: rgba(210, 138, 0, 0.4);
}

.capacity-track.severe {
  border-color: rgba(194, 59, 59, 0.4);
}

.capacity-track::after {
  content: "1 ms 容量";
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  color: #66788a;
  font-size: 12px;
  font-weight: 900;
  z-index: 2;
}

.capacity-track span {
  display: block;
  width: var(--fill);
  height: 100%;
  background: linear-gradient(90deg, rgba(31, 111, 235, 0.78), rgba(17, 132, 91, 0.78));
}

.capacity-track.overflow span,
.capacity-track.severe span {
  background: linear-gradient(90deg, rgba(210, 138, 0, 0.8), rgba(194, 59, 59, 0.78));
}

.capacity-track b {
  position: absolute;
  right: 10px;
  top: 50%;
  z-index: 2;
  transform: translateY(-50%);
  padding: 2px 8px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.78);
  color: #243242;
  font-size: 12px;
  font-weight: 900;
  line-height: 1.35;
}

.capacity-track.near b {
  color: #0f5f4b;
}

.capacity-track.overflow b,
.capacity-track.severe b {
  color: #7a2e0e;
}

.queue-row strong,
.queue-row em {
  color: #526376;
  font-style: normal;
  font-weight: 900;
}

.queue-track {
  display: flex;
  gap: 7px;
  min-height: 48px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #f8fafc;
}

.queue-track span,
.queue-track i {
  width: 28px;
  height: 24px;
  border-radius: 5px;
  background: var(--blue);
}

.queue-track span:nth-child(even) {
  background: var(--green);
}

.queue-track i {
  background: var(--red);
}

.packet-visual {
  display: grid;
  grid-template-columns: 0.7fr 0.8fr 0.9fr minmax(180px, 2.2fr) 0.8fr 0.8fr 0.8fr;
  min-width: 680px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 7px;
}

.packet-visual span {
  display: grid;
  place-items: center;
  min-height: 58px;
  padding: 8px;
  border-right: 1px solid var(--line);
  background: #f8fafc;
  color: #405169;
  font-size: 13px;
  font-weight: 900;
  text-align: center;
}

.packet-visual span:last-child {
  border-right: 0;
}

.packet-visual .payload {
  color: #12345b;
  background: var(--blue-soft);
}

.t1s-visual {
  grid-template-columns: 1fr 1.4fr repeat(5, 1fr);
}

.t1s-visual span:first-child {
  color: #12345b;
  background: var(--blue-soft);
}

.t1s-visual span:nth-child(2) {
  color: #0f4b5a;
  background: var(--cyan-soft);
}

.control-stack div {
  grid-template-columns: minmax(180px, 0.8fr) minmax(0, 1fr);
  justify-items: stretch;
  text-align: left;
}

.control-stack strong {
  color: #17202a;
}

.control-stack span {
  color: #526376;
  font-weight: 700;
}

.bus-split-visual,
.split-flow,
.access-modes {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
}

.bus-split-visual > div,
.access-card {
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #f8fafc;
}

.bus-node,
.bus-line-label,
.arch-main,
.arch-backbone,
.arch-edge-title,
.flow-center {
  padding: 10px 12px;
  border-radius: 7px;
  font-weight: 900;
  text-align: center;
}

.bus-node,
.arch-main {
  color: #12345b;
  background: var(--blue-soft);
  border: 1px solid rgba(31, 111, 235, 0.2);
}

.bus-line-label,
.arch-backbone {
  margin: 8px 0;
  color: #0f4b5a;
  background: var(--cyan-soft);
  border: 1px solid rgba(14, 116, 144, 0.22);
}

.motor-chain,
.branch-list,
.arch-gateways,
.arch-edge,
.arch-side,
.access-flow {
  display: grid;
  gap: 10px;
}

.motor-chain {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.motor-chain span,
.branch-list span {
  padding: 8px 9px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  font-size: 13px;
  font-weight: 800;
  text-align: center;
}

.ethercat-visual,
.architecture-visual {
  display: grid;
  gap: 14px;
}

.ec-block {
  padding: 18px;
  border: 1px solid rgba(31, 111, 235, 0.2);
  border-radius: 7px;
  background: var(--blue-soft);
}

.ec-block h3 {
  margin-bottom: 10px;
}

.ec-block > span {
  display: inline-block;
  margin: 0 6px 6px 0;
  padding: 7px 9px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  font-size: 13px;
  font-weight: 800;
}

.ec-link {
  color: #0f4b5a;
  font-size: 13px;
  font-weight: 900;
  text-align: center;
}

.ec-link::before,
.ec-link::after,
.arch-backbone::before,
.arch-edge-title::before {
  content: "";
  display: block;
  width: 1px;
  height: 12px;
  margin: 0 auto 6px;
  background: var(--line);
}

.ec-device {
  background: var(--green-soft);
  border-color: rgba(17, 132, 91, 0.24);
}

.ec-soft {
  background: #f5f7fa;
  border-color: rgba(112, 128, 144, 0.25);
}

.chip-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-bottom: 10px;
}

.split-flow {
  grid-template-columns: minmax(0, 1fr) 150px minmax(0, 1fr);
  align-items: stretch;
}

.flow-lane {
  display: grid;
  gap: 10px;
  padding: 18px;
  border: 1px solid rgba(31, 111, 235, 0.2);
  border-radius: 7px;
  background: var(--blue-soft);
}

.control-lane {
  border-color: rgba(17, 132, 91, 0.24);
  background: var(--green-soft);
}

.flow-lane em {
  color: #526376;
  font-size: 13px;
  font-style: normal;
  font-weight: 900;
  text-align: center;
}

.flow-center {
  display: grid;
  place-items: center;
  color: #0f4b5a;
  background: var(--cyan-soft);
  border: 1px solid rgba(14, 116, 144, 0.22);
}

.architecture-visual {
  padding: 4px 0;
}

.arch-backbone,
.arch-edge-title {
  margin: 0;
}

.arch-gateways {
  grid-template-columns: repeat(5, minmax(0, 1fr));
}

.arch-edge-title {
  color: #0f5f4b;
  background: var(--green-soft);
  border: 1px solid rgba(17, 132, 91, 0.24);
}

.arch-edge {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

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

.arch-side span {
  padding: 9px 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #f8fafc;
  color: #526376;
  font-size: 13px;
  font-weight: 800;
  text-align: center;
}

.access-modes {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 28px 0;
}

.access-flow {
  margin: 12px 0;
}

.faq-list {
  display: grid;
  gap: 12px;
  max-width: var(--read);
  margin: 28px 0;
}

.faq-list details {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.faq-list summary {
  cursor: pointer;
  padding: 16px 18px;
  color: #243246;
  font-weight: 900;
  list-style-position: inside;
}

.faq-list details[open] summary {
  border-bottom: 1px solid var(--line);
  background: #f8fafc;
}

.faq-list p {
  margin: 0;
  padding: 16px 18px 18px;
  line-height: 1.78;
}

.layer-stack {
  display: grid;
  gap: 12px;
  margin: 20px 0;
}

.layer-stack > div {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 12px;
  align-items: stretch;
}

.layer-stack strong {
  display: grid;
  place-items: center;
  padding: 14px;
  border: 1px solid rgba(31, 111, 235, 0.2);
  border-radius: 7px;
  color: #12345b;
  background: var(--blue-soft);
  text-align: center;
}

.layer-stack > div:nth-child(2) strong {
  color: #0f4b5a;
  border-color: rgba(14, 116, 144, 0.22);
  background: var(--cyan-soft);
}

.layer-stack > div:nth-child(3) strong {
  color: #0f5f4b;
  border-color: rgba(17, 132, 91, 0.24);
  background: var(--green-soft);
}

.layer-stack > div:nth-child(4) strong,
.layer-stack > div:nth-child(5) strong {
  color: #405169;
  border-color: rgba(112, 128, 144, 0.25);
  background: #f5f7fa;
}

.layer-stack p {
  margin: 0;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
}

.term-search {
  width: 100%;
  max-width: var(--read);
  height: 48px;
  margin: 22px 0 18px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--ink);
  background: #fff;
  font: inherit;
}

.term-groups {
  display: grid;
  gap: 14px;
}

.term-group {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.term-group[hidden] {
  display: none;
}

.term-group summary {
  cursor: pointer;
  padding: 15px 18px;
  color: #243246;
  font-weight: 900;
  list-style-position: inside;
}

.term-group[open] summary {
  border-bottom: 1px solid var(--line);
  background: #f8fafc;
}

.term-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  padding: 16px;
}

.term {
  position: relative;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.term::before {
  content: attr(data-priority);
  position: absolute;
  top: 12px;
  right: 12px;
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  border-radius: 999px;
  color: #526376;
  background: #f4f7fa;
  font-size: 12px;
  font-weight: 900;
}

.term[data-priority="A"]::before {
  color: #1f4f8f;
  background: var(--blue-soft);
}

.term[data-priority="B"]::before {
  color: #0f5f4b;
  background: var(--green-soft);
}

.term h3 {
  padding-right: 32px;
}

.term p {
  margin-bottom: 0;
  font-size: 15px;
  line-height: 1.72;
}

.term[hidden] {
  display: none;
}

@media (max-width: 980px) {
  .hero,
  .compare-diagram,
  .split-diagram,
  .concept-grid,
  .method-grid,
  .case-grid,
  .compare-mini,
  .concept-grid.three,
  .issue-flow,
  .bus-split-visual,
  .split-flow,
  .access-modes,
  .term-grid {
    grid-template-columns: 1fr;
  }

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

  .layer-stack > div {
    grid-template-columns: 1fr;
  }

  .flow-arrow::after {
    content: "↓";
  }

  .arch-gateways,
  .case-flow,
  .t1s-visual,
  .arch-side {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .header-inner,
  .hero,
  .content-shell {
    width: min(100% - 22px, var(--max));
  }

  .header-inner {
    align-items: stretch;
    flex-direction: column;
    gap: 8px;
    padding: 10px 0;
  }

  .top-nav {
    padding-bottom: 2px;
  }

  .hero {
    padding-top: 30px;
    padding-bottom: 30px;
  }

  .hero-actions,
  .gateway-row,
  .edge-grid,
  .side-notes,
  .case-grid,
  .case-flow,
  .compare-mini,
  .t1s-visual,
  .control-stack div,
  .motor-chain,
  .chip-row,
  .arch-gateways,
  .arch-edge,
  .arch-side {
    grid-template-columns: 1fr;
  }

  .toc {
    padding: 12px;
  }

  .toc a {
    flex: 1 1 100%;
  }

  .teaching-figure {
    padding: 13px;
  }

  .teaching-figure figcaption,
  .figure-title {
    align-items: flex-start;
    flex-direction: column;
    gap: 4px;
  }

  h1 {
    font-size: 30px;
    line-height: 1.16;
  }

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

  .hero-actions a {
    min-height: 48px;
    font-size: 14px;
  }

  .chapter-head {
    align-items: flex-start;
    flex-direction: column;
    gap: 9px;
  }

  .hero-map,
  .compare-diagram > div,
  .split-diagram > div,
  .concept-grid > div,
  .method-grid > div {
    padding: 14px;
  }
}