:root {
  --bg: #fbfbf8;
  --bg-warm: #f6f2ea;
  --panel: #ffffff;
  --text: #1b1b1f;
  --muted: #676a70;
  --faint: #8c9097;
  --line: #dedfdc;
  --line-strong: #c9cac6;
  --soft: #f3f5f4;
  --link: #225f8f;
  --link-soft: #edf5fb;
  --accent: #9d3b32;
  --accent-soft: #fbefed;
  --green: #356d5b;
  --green-soft: #edf6f2;
  --gold: #8a6422;
  --gold-soft: #faf4e5;
  --shadow: 0 18px 50px rgba(31, 34, 37, 0.07);
  --shadow-sm: 0 8px 26px rgba(31, 34, 37, 0.06);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  background:
    linear-gradient(180deg, #ffffff 0, var(--bg-warm) 220px, var(--bg) 520px),
    var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.68;
}

a {
  color: var(--link);
  text-decoration: none;
  text-underline-offset: 3px;
}

a:hover {
  text-decoration: underline;
}

.citation {
  display: inline-block;
  margin-left: 2px;
  color: var(--link);
  font-size: 0.82em;
  font-weight: 760;
  line-height: 1;
  vertical-align: 0.18em;
}

.citation + .citation {
  margin-left: 1px;
}

.citation:hover {
  color: var(--accent);
  text-decoration: none;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 60px;
  padding: 10px max(24px, calc((100vw - 1240px) / 2));
  background: rgba(251, 251, 248, 0.9);
  border-bottom: 1px solid rgba(201, 202, 198, 0.76);
  box-shadow: 0 1px 18px rgba(31, 34, 37, 0.045);
  backdrop-filter: blur(14px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  color: var(--text);
  font-size: 0.98rem;
  font-weight: 780;
  letter-spacing: 0;
}

.brand::before {
  width: 10px;
  height: 10px;
  border: 2px solid var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
  border-radius: 50%;
  content: "";
}

.topnav {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  color: var(--muted);
  font-size: 0.93rem;
  white-space: nowrap;
}

.topnav a {
  padding: 6px 9px;
  color: var(--muted);
  border-radius: 7px;
}

.topnav a:hover {
  color: var(--text);
  background: rgba(34, 95, 143, 0.08);
  text-decoration: none;
}

.layout {
  display: grid;
  grid-template-columns: 228px minmax(0, 900px);
  gap: 64px;
  width: min(1240px, calc(100% - 48px));
  margin: 0 auto;
}

.sidebar {
  position: sticky;
  top: 80px;
  align-self: start;
  max-height: calc(100vh - 98px);
  padding: 34px 0;
  overflow-y: auto;
  color: var(--muted);
  font-size: 0.9rem;
}

.sidebar nav {
  display: grid;
  gap: 4px;
  padding: 8px 0 8px 14px;
  border-left: 1px solid var(--line-strong);
}

.sidebar a,
.sidebar summary {
  display: block;
  padding: 6px 8px;
  color: var(--muted);
  border-radius: 7px;
}

.chapter-nav details {
  margin: 0;
}

.chapter-nav summary {
  display: flex;
  align-items: center;
  gap: 5px;
  cursor: pointer;
  list-style: none;
}

.chapter-nav summary::-webkit-details-marker {
  display: none;
}

.chapter-nav summary::before {
  width: 0;
  height: 0;
  border-top: 4px solid transparent;
  border-bottom: 4px solid transparent;
  border-left: 5px solid #9ca0a5;
  content: "";
  transition: transform 160ms ease;
}

.chapter-nav details[open] summary::before {
  transform: rotate(90deg);
}

.chapter-nav summary a {
  flex: 1;
  min-width: 0;
  padding: 0;
  color: #42464c;
  font-weight: 720;
}

.chapter-nav summary:hover {
  color: var(--text);
  background: rgba(34, 95, 143, 0.07);
}

.chapter-nav summary:hover a {
  color: var(--text);
  text-decoration: none;
}

.sidebar a.nav-section {
  margin-top: 8px;
  color: #42464c;
  font-weight: 720;
}

.sidebar a.nav-section:first-child {
  margin-top: 0;
}

.sidebar a.nav-sub {
  position: relative;
  margin: 1px 0 1px 15px;
  padding: 4px 8px 4px 11px;
  color: #73777d;
  font-size: 0.82rem;
  line-height: 1.35;
}

.sidebar a:hover {
  color: var(--text);
  background: rgba(34, 95, 143, 0.07);
  text-decoration: none;
}

.content {
  min-width: 0;
}

.book-hero,
.reader-title {
  position: relative;
  padding: 88px 0 52px;
  border-bottom: 1px solid var(--line);
}

.book-hero::after,
.reader-title::after {
  position: absolute;
  right: 0;
  bottom: -1px;
  width: min(260px, 48%);
  height: 3px;
  background: linear-gradient(90deg, var(--link), var(--accent), var(--green));
  content: "";
}

.kicker {
  margin: 0 0 13px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 780;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p,
li,
td,
th {
  overflow-wrap: anywhere;
}

h1 {
  max-width: 920px;
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2.35rem, 4.35vw, 4.35rem);
  font-weight: 520;
  line-height: 1.08;
  letter-spacing: 0;
}

.subtitle {
  max-width: 760px;
  margin: 18px 0 0;
  color: #303238;
  font-size: clamp(1.3rem, 2.35vw, 1.85rem);
  line-height: 1.35;
}

.authors {
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 0.98rem;
}

.authors sup,
.affiliations sup {
  margin-left: 1px;
  margin-right: 1px;
  font-size: 0.7em;
  line-height: 0;
}

.affiliations {
  margin: 8px 0 0;
  color: #676a70;
  font-size: 0.9rem;
  line-height: 1.45;
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 26px;
}

.action-row a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 7px 13px;
  color: var(--text);
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  font-weight: 700;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.03);
}

.action-row a:first-child {
  color: #ffffff;
  background: var(--text);
  border-color: var(--text);
}

.action-row a:hover {
  border-color: #b8bab8;
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
  text-decoration: none;
}

.topic-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 20px;
}

.topic-pills span {
  padding: 5px 10px;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--line);
  border-radius: 8px;
  font-size: 0.84rem;
  font-weight: 650;
}

.block,
.chapter {
  padding: 54px 0;
  border-bottom: 1px solid var(--line);
}

.block {
  scroll-margin-top: 82px;
}

h2 {
  margin: 0 0 18px;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.65rem, 2.8vw, 2.35rem);
  font-weight: 520;
  line-height: 1.18;
  letter-spacing: 0;
}

h3 {
  margin: 34px 0 11px;
  color: #25272b;
  font-size: 1.04rem;
  line-height: 1.35;
}

p {
  margin: 0 0 15px;
}

.lead {
  color: #303238;
  font-size: 1.08rem;
  line-height: 1.72;
}

.chapter-list {
  margin: 8px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: chapters;
  border-top: 1px solid var(--line);
}

.chapter-list li {
  position: relative;
  scroll-margin-top: 90px;
  padding: 19px 0 19px 58px;
  border-bottom: 1px solid var(--line);
  counter-increment: chapters;
  transition: background 160ms ease;
}

.chapter-list li:hover {
  background: rgba(255, 255, 255, 0.48);
}

.chapter-list li::before {
  position: absolute;
  left: 0;
  top: 19px;
  width: 38px;
  color: var(--accent);
  content: counter(chapters, decimal-leading-zero);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.12rem;
  font-variant-numeric: tabular-nums;
}

.chapter-list a {
  color: var(--text);
  font-weight: 760;
}

.chapter-list a:hover {
  color: var(--link);
}

.chapter-title-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

.chapter-list .chapter-pdf {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 42px;
  min-height: 24px;
  padding: 3px 9px;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid rgba(157, 59, 50, 0.22);
  border-radius: 7px;
  font-size: 0.72rem;
  font-weight: 800;
  line-height: 1;
  letter-spacing: 0.04em;
}

.chapter-list .chapter-pdf:hover {
  color: #ffffff;
  background: var(--accent);
  border-color: var(--accent);
  text-decoration: none;
}

.chapter-list p {
  margin: 5px 0 0;
  color: #3e4146;
}

.material-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin-top: 20px;
}

.material {
  display: block;
  min-height: 134px;
  padding: 18px;
  color: var(--text);
  background: linear-gradient(180deg, #ffffff, #fbfcfc);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.035);
  transition: border-color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.material:hover {
  border-color: #c3c5c2;
  box-shadow: var(--shadow-sm);
  transform: translateY(-2px);
  text-decoration: none;
}

.material span {
  color: var(--link);
  font-weight: 780;
}

.material p {
  margin: 7px 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

table {
  width: 100%;
  margin: 18px 0 28px;
  border-collapse: separate;
  border-spacing: 0;
  overflow: hidden;
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.03);
}

th,
td {
  padding: 13px 15px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}

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

th {
  color: var(--text);
  background: #f0f2f1;
  font-size: 0.88rem;
  letter-spacing: 0;
}

td {
  color: #34363a;
}

tbody tr:nth-child(even) td {
  background: #fcfcfb;
}

tbody tr:hover td {
  background: #f7faf9;
}

pre {
  overflow-x: auto;
  margin: 0;
  padding: 18px;
  background: #f6f7f8;
  border: 1px solid var(--line);
  border-radius: 8px;
}

code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.9rem;
}

.reader-content {
  max-width: 840px;
}

.reader-title > p:not(.kicker) {
  max-width: 740px;
  color: #34363a;
  font-size: 1.04rem;
}

.reader-title h1 {
  max-width: 760px;
  font-size: clamp(2.15rem, 3.7vw, 3.65rem);
  line-height: 1.1;
}

.lesson-map {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin-top: 26px;
}

.lesson-map a {
  display: block;
  padding: 11px 13px;
  color: #2d3136;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  font-size: 0.92rem;
  font-weight: 700;
  transition: border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.lesson-map a:hover {
  color: var(--link);
  border-color: #c3c7c9;
  transform: translateY(-1px);
  text-decoration: none;
}

.chapter {
  scroll-margin-top: 82px;
}

.chapter h3 {
  scroll-margin-top: 82px;
}

.chapter h4 {
  margin: 28px 0 10px;
  color: #34363a;
  font-size: 1rem;
  line-height: 1.35;
}

.lesson-card,
.callout,
.recap-card {
  margin: 22px 0 26px;
  padding: 18px 20px;
  background: #ffffff;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
}

.lesson-card {
  background: linear-gradient(180deg, #ffffff, var(--green-soft));
  border-left: 4px solid var(--green);
}

.lesson-card h3,
.recap-card h3 {
  margin-top: 0;
}

.lesson-card ul {
  margin: 0;
  padding-left: 20px;
}

.lesson-card li + li {
  margin-top: 6px;
}

.callout {
  color: #31343a;
  background: var(--link-soft);
  border-color: #cfe2ee;
  border-left: 4px solid var(--link);
}

.callout.warning {
  background: var(--accent-soft);
  border-color: #ecd0cb;
  border-left-color: var(--accent);
}

.callout strong {
  color: var(--text);
}

.quote-block {
  margin: 26px 0 34px;
  padding: 0;
}

.quote-block blockquote {
  margin: 0;
  padding: 3px 0 3px 24px;
  color: #22252a;
  background: transparent;
  border: 0;
  border-left: 3px solid var(--gold);
  border-radius: 0;
  box-shadow: none;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.2rem;
  line-height: 1.55;
}

.quote-block figcaption {
  margin-top: 10px;
  padding-left: 24px;
  color: var(--muted);
  font-size: 0.92rem;
  text-align: right;
}

.recap-card {
  background: linear-gradient(180deg, #ffffff, var(--gold-soft));
  border-left: 4px solid var(--accent);
}

.recap-card p:last-child,
.callout p:last-child {
  margin-bottom: 0;
}

.step-flow {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  margin: 22px 0 30px;
}

.step-flow div {
  min-height: 132px;
  padding: 14px;
  background: linear-gradient(180deg, #ffffff, #fbfcfc);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.03);
}

.step-flow span {
  display: inline-grid;
  place-items: center;
  min-width: 26px;
  height: 26px;
  padding: 0 6px;
  margin-bottom: 10px;
  color: #ffffff;
  background: var(--text);
  border-radius: 50%;
  font-size: 0.82rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.step-flow strong {
  display: block;
  margin-bottom: 5px;
  color: var(--text);
}

.step-flow p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.48;
}

.stage-list,
.revision-flow {
  display: grid;
  gap: 12px;
  margin: 22px 0 30px;
}

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

.stage-list div {
  padding: 16px 17px;
  background: #ffffff;
  border: 1px solid var(--line-strong);
  border-top: 3px solid var(--green);
  border-radius: 8px;
}

.stage-list strong,
.revision-flow strong {
  display: block;
  margin-bottom: 5px;
  color: var(--text);
}

.stage-list p,
.revision-flow p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.5;
}

.stage-list span {
  display: block;
  margin-bottom: 8px;
  color: var(--green);
  font-size: 0.75rem;
  font-weight: 780;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.cycle-flow div {
  background: linear-gradient(180deg, #ffffff, var(--green-soft));
  border-color: #cbded6;
}

.cycle-flow span {
  background: var(--green);
}

.revision-flow {
  grid-template-columns: repeat(5, minmax(0, 1fr));
  counter-reset: revision;
}

.revision-flow div {
  position: relative;
  padding: 15px 14px 16px;
  background: linear-gradient(180deg, #ffffff, #fbfaf6);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  counter-increment: revision;
}

.revision-flow div::before {
  display: inline-grid;
  place-items: center;
  width: 24px;
  height: 24px;
  margin-bottom: 10px;
  color: #ffffff;
  background: var(--gold);
  border-radius: 6px;
  content: counter(revision);
  font-size: 0.78rem;
  font-weight: 800;
}

.concept-table {
  margin: 22px 0 28px;
  font-size: 0.95rem;
}

.concept-table.compact th,
.concept-table.compact td {
  padding-top: 10px;
  padding-bottom: 10px;
}

.concept-table td:first-child {
  color: var(--text);
  font-weight: 740;
}

.rl-mapping-table {
  table-layout: fixed;
}

.rl-mapping-table .rl-element-col {
  width: 23%;
}

.rl-mapping-table .rl-interpretation-col {
  width: 77%;
}

.rl-mapping-table th,
.rl-mapping-table td {
  vertical-align: top;
}

.table-scroll {
  width: 100%;
  margin: 18px 0 30px;
  overflow-x: visible;
}

.resource-table {
  table-layout: fixed;
  min-width: 0;
  margin: 0;
  font-size: 0.76rem;
  line-height: 1.36;
}

.resource-table th,
.resource-table td {
  padding: 7px 8px;
  overflow-wrap: anywhere;
}

.resource-table th {
  padding-right: 10px;
  padding-left: 10px;
}

.resource-table td:first-child {
  color: var(--text);
  font-weight: 740;
  overflow-wrap: normal;
}

.systems-table th:nth-child(n+2):nth-child(-n+5),
.systems-table td:nth-child(n+2):nth-child(-n+5) {
  width: 5%;
  text-align: center;
  white-space: nowrap;
}

.datasets-table th:nth-child(n+2):nth-child(-n+4),
.datasets-table td:nth-child(n+2):nth-child(-n+4) {
  width: 8%;
  text-align: center;
  white-space: nowrap;
}

.systems-table th:first-child,
.systems-table td:first-child {
  width: 13%;
}

.datasets-table th:first-child,
.datasets-table td:first-child {
  width: 22%;
}

.datasets-table th:nth-child(5),
.datasets-table td:nth-child(5) {
  width: 10%;
  white-space: nowrap;
}

.datasets-table th:nth-child(6),
.datasets-table td:nth-child(6),
.datasets-table th:nth-child(7),
.datasets-table td:nth-child(7) {
  width: 12%;
}

.systems-table th:last-child,
.systems-table td:last-child,
.datasets-table th:last-child,
.datasets-table td:last-child {
  width: 20%;
  min-width: 0;
}

.systems-table th:last-child,
.systems-table td:last-child {
  width: 47%;
  min-width: 0;
}

.rl-mapping-table th:first-child,
.rl-mapping-table td:first-child {
  white-space: nowrap;
}

.rl-mapping-table td:nth-child(2) {
  color: #22252a;
  font-size: 0.95rem;
  white-space: normal;
  overflow-wrap: anywhere;
  word-break: normal;
}

.cheat-item,
.glossary-group {
  padding: 42px 0;
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 82px;
}

.cheat-item h2,
.glossary-group h2 {
  margin-bottom: 14px;
}

.chapter-number {
  margin: 0 0 9px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 780;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.equation {
  position: relative;
  overflow-x: auto;
  margin: 22px 0 23px;
  padding: 18px 22px 18px 26px;
  color: #17181c;
  background:
    linear-gradient(90deg, rgba(34, 95, 143, 0.08), rgba(34, 95, 143, 0) 120px),
    linear-gradient(180deg, #ffffff, #fafafa);
  border: 1px solid #d8d9d5;
  border-left: 3px solid var(--link);
  border-radius: 8px;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.03);
  font-size: 1.03rem;
  line-height: 1.55;
  text-align: center;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}

.equation::before {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--link), var(--accent));
  content: "";
}

.equation .katex-display {
  margin: 0;
}

.equation .katex {
  font-size: 1.08em;
  line-height: 1.4;
}

.equation .katex-html {
  min-width: max-content;
}

.equation sub,
.equation sup {
  line-height: 0;
}

.derivation {
  margin: 22px 0 27px;
  padding: 18px 20px 20px;
  overflow-x: auto;
  background:
    linear-gradient(90deg, rgba(138, 100, 34, 0.08), rgba(138, 100, 34, 0) 140px),
    #ffffff;
  border: 1px solid var(--line-strong);
  border-left: 4px solid var(--gold);
  border-radius: 8px;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.035);
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}

.derivation-label {
  margin: 0 0 14px;
  color: var(--gold);
  font-size: 0.78rem;
  font-weight: 780;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.derivation .equation {
  overflow-x: visible;
  margin: 0;
  padding: 9px 0;
  background: transparent;
  border: 0;
  border-radius: 0;
  box-shadow: none;
  font-size: 0.96rem;
  text-align: center;
}

.derivation .equation + .equation {
  margin-top: 7px;
  padding-top: 16px;
  border-top: 1px solid rgba(201, 202, 198, 0.72);
}

.derivation .equation::before {
  display: none;
}

.derivation p:not(.derivation-label) {
  margin: 14px 0 0;
  color: #3e4146;
  font-size: 0.94rem;
  line-height: 1.62;
}

.compact-derivation {
  margin-top: 18px;
}

.notation-note {
  margin: -8px 0 24px;
  color: var(--muted);
  font-size: 0.94rem;
  line-height: 1.62;
}

.paper-figure {
  margin: 26px 0 30px;
  overflow: hidden;
  border-radius: 8px;
}

.paper-figure img {
  display: block;
  width: 100%;
  height: auto;
  padding: 10px;
  background: #ffffff;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
  transform-origin: center;
  transition: transform 220ms ease, box-shadow 220ms ease, border-color 220ms ease;
  will-change: transform;
}

.paper-figure:hover img {
  border-color: #b8c3c8;
  box-shadow: 0 18px 44px rgba(31, 34, 37, 0.13);
  transform: scale(1.018);
}

.paper-figure figcaption {
  max-width: 96%;
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.55;
}

.update-note {
  margin: 18px 0 0;
  padding-left: 14px;
  color: var(--muted);
  font-size: 0.94rem;
  line-height: 1.62;
  border-left: 3px solid var(--accent);
}

.note-list {
  display: grid;
  gap: 0;
  margin: 22px 0 0;
  padding: 0;
  color: #34363a;
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  overflow: hidden;
}

.note-list div {
  padding: 12px 14px;
}

.note-list div:nth-child(odd) {
  background: #fafafa;
}

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

.note-list strong {
  color: var(--text);
}

.glossary-list {
  display: grid;
  grid-template-columns: minmax(170px, 0.32fr) minmax(0, 1fr);
  margin: 18px 0 0;
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.03);
}

.glossary-list dt,
.glossary-list dd {
  margin: 0;
  padding: 15px 16px;
  border-bottom: 1px solid var(--line);
}

.glossary-list dt {
  color: var(--text);
  background: linear-gradient(180deg, #fbfbfa, #f6f7f6);
  border-right: 1px solid var(--line);
  font-weight: 760;
  line-height: 1.35;
}

.glossary-list dd {
  color: #34363a;
  line-height: 1.68;
  background: rgba(255, 255, 255, 0.72);
}

.math {
  color: #1f2933;
  font-family: Georgia, "Times New Roman", serif;
  font-style: italic;
  white-space: nowrap;
}

.math-vector {
  font-style: italic;
  font-weight: 700;
}

.reading-note {
  margin: 8px 0 0;
  color: var(--faint);
  font-size: 0.92rem;
  font-style: italic;
  line-height: 1.5;
}

.reading-note span:first-child {
  color: var(--gold);
  font-style: normal;
  font-weight: 780;
}

.reading-note .paper-title {
  color: #4c5057;
}

.reading-note a {
  font-style: normal;
  font-weight: 700;
}

.glossary-list dt:has(+ dd:hover),
.glossary-list dd:hover {
  background: #f7faf9;
}

.glossary-list dt:last-of-type,
.glossary-list dd:last-of-type {
  border-bottom: 0;
}

.reader-footer {
  display: flex;
  gap: 18px;
  padding: 32px 0 74px;
  font-weight: 700;
}

.references {
  padding-bottom: 22px;
}

.reference-list {
  margin: 18px 0 0;
  padding-left: 0;
  list-style: none;
  counter-reset: refs;
  border-top: 1px solid var(--line);
}

.reference-list li {
  position: relative;
  padding: 14px 0 14px 46px;
  color: #34363a;
  border-bottom: 1px solid var(--line);
  counter-increment: refs;
  font-size: 0.94rem;
  line-height: 1.55;
}

.reference-list li::before {
  position: absolute;
  left: 0;
  top: 14px;
  width: 34px;
  color: var(--link);
  content: "[" counter(refs) "]";
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.reference-list li:target {
  margin-left: -10px;
  padding-left: 56px;
  background: var(--gold-soft);
  border-radius: 8px;
  scroll-margin-top: 82px;
}

.footer {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 16px 28px;
  width: min(1240px, calc(100% - 48px));
  margin: 0 auto;
  padding: 24px 0 42px;
  color: var(--muted);
  font-size: 0.92rem;
  border-top: 1px solid var(--line);
}

.footer-copy {
  min-width: min(100%, 360px);
}

.footer-actions {
  display: inline-flex;
  align-items: center;
  gap: 16px;
  margin-left: auto;
  white-space: nowrap;
}

.footer-actions > a {
  color: var(--link);
  font-weight: 700;
}

.flag-counter {
  display: inline-flex;
  align-items: center;
  padding: 3px;
  background: #ffffff;
  border: 1px solid var(--line-strong);
  border-radius: 7px;
  line-height: 0;
  box-shadow: 0 1px 0 rgba(31, 34, 37, 0.04);
}

.flag-counter:hover {
  border-color: #b8c3c8;
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
  text-decoration: none;
}

.flag-counter img {
  display: block;
  width: 112px;
  height: auto;
}

@media (max-width: 940px) {
  .layout {
    display: block;
    width: min(860px, calc(100% - 44px));
  }

  .sidebar {
    position: static;
    max-height: none;
    padding: 18px 0 0;
    border-bottom: 1px solid var(--line);
  }

  .sidebar nav {
    display: flex;
    gap: 15px;
    overflow-x: auto;
    padding: 0 0 14px;
    border-left: 0;
    white-space: nowrap;
  }

  .book-hero,
  .reader-title {
    padding-top: 48px;
  }
}

@media (max-width: 640px) {
  body {
    font-size: 15.5px;
  }

  .topbar {
    align-items: flex-start;
    flex-direction: column;
    gap: 7px;
    padding-left: 22px;
    padding-right: 22px;
  }

  .topnav {
    width: 100%;
  }

  .layout,
  .footer {
    width: min(100% - 36px, 860px);
  }

  .book-hero,
  .reader-title {
    padding: 42px 0 34px;
  }

  .block,
  .chapter,
  .cheat-item,
  .glossary-group {
    padding: 38px 0;
  }

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

  .material {
    min-height: auto;
  }

  .lesson-map,
  .step-flow,
  .stage-list,
  .revision-flow {
    grid-template-columns: 1fr;
  }

  .step-flow div {
    min-height: auto;
  }

  table {
    display: block;
    overflow-x: auto;
    border-radius: 8px;
  }

  .resource-table {
    display: table;
    overflow-x: visible;
  }

  .paper-figure img {
    padding: 6px;
    border-radius: 8px;
  }

  .equation {
    margin-left: -4px;
    margin-right: -4px;
    padding: 15px 14px 15px 17px;
    font-size: 0.96rem;
    text-align: left;
  }

  .derivation {
    padding: 16px 15px 17px;
  }

  .derivation .equation {
    margin-left: 0;
    margin-right: 0;
    padding: 8px 0;
    font-size: 0.9rem;
    text-align: center;
  }

  .derivation .equation + .equation {
    padding-top: 14px;
  }

  .glossary-list {
    display: block;
  }

  .glossary-list dt {
    border-bottom: 0;
  }

  .glossary-list dd {
    padding-top: 0;
  }

  .footer {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-actions {
    margin-left: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}