@charset "UTF-8";
:root {
  --paper: #f6f3eb;
  --surface: #fffdf7;
  --ink: #24352d;
  --muted: #5f6b60;
  --line: #d9ddd0;
  --green: #245640;
  --pale: #e9eee2;
  --gold: #ab622c;
  --reader-size: 20px;
  --shadow: 0 18px 55px #263b2520;
  color-scheme: light;
  font-family:
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  color: var(--ink);
  background: var(--paper);
  font-size: 17px;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
}
button,
input,
select {
  font: inherit;
}
button,
a,
input,
select {
  -webkit-tap-highlight-color: transparent;
}
button,
a {
  touch-action: manipulation;
}
button {
  cursor: pointer;
  color: inherit;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 7px;
  min-height: 46px;
  padding: 10px 15px;
  line-height: 1.3;
}
button:hover {
  background: var(--pale);
}
button:disabled {
  opacity: 0.4;
  cursor: default;
}
a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 4px;
}
h1,
h2,
h3,
p {
  margin-top: 0;
}
h1,
h2,
h3 {
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 400;
  line-height: 1.12;
}
p {
  line-height: 1.65;
}
.muted {
  color: var(--muted);
}
.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.13em;
  font-size: 0.8rem;
  font-weight: 650;
  color: var(--muted);
  margin-bottom: 16px;
}
.icon {
  width: 22px;
  height: 22px;
  display: block;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.65;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.icon-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 46px;
  padding: 10px;
  background: transparent;
}
.skip {
  position: fixed;
  z-index: 30;
  top: -100px;
  left: 15px;
  background: var(--surface);
  padding: 15px;
}
.skip:focus {
  top: 10px;
}
.topbar {
  height: 86px;
  border-bottom: 1px solid var(--line);
  padding: 0 clamp(20px, 4vw, 68px);
  display: flex;
  align-items: center;
  gap: 35px;
  background: var(--paper);
  position: relative;
  z-index: 5;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  font-family: Georgia, serif;
  font-size: 26px;
  flex-shrink: 0;
}
.brand small {
  display: block;
  font-family: system-ui, sans-serif;
  font-size: 10px;
  letter-spacing: 0.16em;
  margin-top: 5px;
  font-weight: 600;
}
.brand-mark {
  font-family: Georgia, serif;
  font-size: 35px;
  background: var(--green);
  color: #fffdf7;
  display: grid;
  place-items: center;
  width: 45px;
  height: 48px;
  border-radius: 4px;
}
.topbar nav {
  display: flex;
  gap: 30px;
  margin-left: auto;
}
.topbar nav a {
  padding: 14px 0;
  text-decoration: none;
  font-size: 16px;
}
.topbar nav a.active {
  box-shadow: 0 2px var(--green);
}
.header-actions {
  display: flex;
  gap: 8px;
}
.header-actions .icon-button {
  border: 0;
}
.primary {
  background: var(--green);
  color: #fffdf7;
  border-color: var(--green);
}
.primary:hover {
  background: #193d2c;
  color: #fffdf7;
}
.button-link {
  display: inline-flex;
  gap: 12px;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  border: 1px solid var(--line);
  padding: 12px 20px;
  border-radius: 6px;
  text-decoration: none;
  font-size: 16px;
  font-weight: 600;
}
.button-link.primary {
  border-color: var(--green);
}
.text-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
}
.page-shell {
  max-width: 1360px;
  margin: 0 auto;
  padding: 55px 45px;
}
.hero {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 70px;
  align-items: center;
  padding-top: 16px;
  padding-bottom: 50px;
}
.hero h1 {
  font-size: clamp(45px, 5.5vw, 78px);
  letter-spacing: -0.045em;
  margin-bottom: 25px;
}
.hero h1 em {
  color: var(--green);
  font-weight: 400;
}
.hero .intro {
  font-size: 20px;
  max-width: 490px;
  color: var(--muted);
}
.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin: 30px 0;
}
.edition {
  font-size: 14px;
  color: var(--muted);
  line-height: 1.6;
}
.hero-board {
  max-width: 460px;
  width: 100%;
  margin: auto;
  transform: rotate(-1deg);
}
.hero-board .lab {
  box-shadow: var(--shadow);
}
.hero-board .lab > * {
  transform: none;
}
.hero-board .move-list {
  display: none;
}
.hero-board .lab {
  border-radius: 12px;
}
.hero-board .lab-head {
  padding: 17px 19px;
}
.hero-board .lab-context {
  display: none;
}
.hero-board .lab-aux {
  display: none;
}
.hero-board .board-status {
  font-size: 14px;
}
.hero-board .board-wrap {
  padding: 0 20px;
}
.hero-board .board-controls {
  padding: 12px 20px;
}
.hero-board .annotation {
  padding: 0 20px 18px;
  min-height: 100px;
  font-size: 16px;
}
.home-note {
  position: relative;
  border-left: 2px solid var(--gold);
  padding-left: 16px;
  margin-top: 23px;
  font-size: 15px;
  color: var(--muted);
}
.stats-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 24px 0;
  margin-bottom: 45px;
  gap: 25px;
}
.stat {
  display: flex;
  gap: 14px;
  align-items: baseline;
}
.stat b {
  font-family: Georgia, serif;
  font-size: 32px;
  font-weight: 400;
}
.stat span {
  color: var(--muted);
  font-size: 15px;
}
.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  margin: 32px 0 23px;
}
.section-heading h2 {
  font-size: 34px;
  margin: 0;
}
.chapter-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}
.chapter-card {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 24px;
  min-height: 195px;
  transition:
    border-color 0.15s,
    transform 0.15s;
}
.chapter-card:hover {
  border-color: var(--green);
  transform: translateY(-2px);
}
.chapter-card h3 {
  font-size: 25px;
  margin: 15px 0 25px;
  line-height: 1.2;
}
.chapter-card .card-meta {
  margin-top: auto;
  display: flex;
  justify-content: space-between;
  gap: 10px;
  font-size: 14px;
  color: var(--muted);
}
.card-number {
  font-size: 14px;
  color: var(--gold);
  letter-spacing: 0.08em;
}
.page-heading {
  max-width: 800px;
  margin-bottom: 40px;
}
.page-heading h1 {
  font-size: 56px;
  letter-spacing: -0.035em;
  margin-bottom: 20px;
}
.page-heading p {
  color: var(--muted);
  font-size: 20px;
}
.resume {
  padding: 20px 24px;
  border-radius: 8px;
  background: var(--pale);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 30px;
}
.resume p {
  margin: 0;
  font-size: 15px;
}
.resume strong {
  display: block;
  margin-top: 5px;
  font-size: 18px;
}
.library-toolbar {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin: 25px 0 35px;
}
.library-toolbar input {
  flex: 1;
  min-width: 200px;
}
.library-toolbar select {
  max-width: 100%;
}
input,
select {
  min-height: 48px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  color: var(--ink);
  padding: 12px 15px;
}
.game-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}
.game-card {
  display: flex;
  justify-content: space-between;
  gap: 15px;
  padding: 19px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 6px;
  text-decoration: none;
  line-height: 1.5;
}
.game-card small {
  display: block;
  color: var(--muted);
  margin-top: 6px;
  font-size: 14px;
}
.reader-shell {
  display: grid;
  grid-template-columns: 230px minmax(0, 1fr) 390px;
  max-width: 1650px;
  margin: auto;
  align-items: start;
}
.toc {
  position: sticky;
  top: 20px;
  max-height: calc(100dvh - 40px);
  overflow: auto;
  padding: 30px 20px 35px 24px;
  font-size: 15px;
}
.toc-title {
  font-size: 12px;
  letter-spacing: 0.14em;
  font-weight: 650;
  margin: 15px 0 10px;
  color: var(--muted);
  text-transform: uppercase;
}
.toc a {
  display: flex;
  gap: 10px;
  text-decoration: none;
  padding: 12px 10px;
  border-radius: 6px;
  line-height: 1.4;
  min-height: 44px;
  margin: 2px 0;
}
.toc a.active {
  background: var(--pale);
  color: var(--green);
  font-weight: 650;
}
.toc .toc-number {
  color: var(--muted);
  min-width: 20px;
}
.toc details > summary {
  cursor: pointer;
  padding: 12px 0;
  min-height: 44px;
}
.reader-content {
  min-width: 0;
  border-left: 1px solid var(--line);
  border-right: 1px solid var(--line);
  padding: 38px clamp(24px, 3.8vw, 64px) 70px;
}
.reader-topline {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
  gap: 10px;
}
.reader-topline .eyebrow {
  margin: 0;
}
.reader-tools {
  display: flex;
  gap: 5px;
}
.reader-tools .icon-button {
  border: 0;
}
.reader-title {
  font-size: clamp(35px, 3.7vw, 55px);
  letter-spacing: -0.03em;
  margin-bottom: 25px;
}
.chapter-summary {
  font-family: system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.6;
  color: var(--muted);
  padding-bottom: 28px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 30px;
}
.prose {
  font-family: Georgia, "Times New Roman", serif;
  font-size: var(--reader-size);
  line-height: 1.75;
  overflow-wrap: break-word;
}
.prose p {
  line-height: 1.75;
  margin: 0 0 1.25em;
}
.prose a {
  color: var(--green);
}
.prose h2 {
  font-size: 1.3em;
  line-height: 1.35;
  margin: 2em 0 0.9em;
}
.prose h3 {
  font-size: 1.2em;
  line-height: 1.4;
}
.prose table {
  font-size: 0.85em;
  border-collapse: collapse;
  min-width: 500px;
}
.prose td,
.prose th {
  padding: 10px;
  border-bottom: 1px solid var(--line);
  text-align: left;
}
.table-scroll {
  max-width: 100%;
  overflow: auto;
}
.block {
  scroll-margin-top: 30px;
}
.block.target {
  border-left: 3px solid var(--gold);
  padding-left: 15px;
}
.section-block {
  position: relative;
}
.section-link {
  font-family: system-ui, sans-serif;
  text-decoration: none;
  font-size: 16px;
  display: inline-grid;
  place-items: center;
  width: 44px;
  height: 44px;
  margin-left: 4px;
}
.diagram-card {
  font-family: system-ui, sans-serif;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 9px;
  margin: 28px 0;
  padding: 20px;
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 22px;
  align-items: center;
  cursor: pointer;
}
.diagram-card:hover,
.diagram-card.selected {
  border-color: var(--green);
}
.diagram-card h3 {
  font-family: system-ui, sans-serif;
  font-size: 17px;
  font-weight: 650;
  margin: 0 0 8px;
}
.diagram-card p {
  font-size: 16px;
  line-height: 1.5;
  margin: 0 0 10px;
}
.diagram-card .button-link {
  font-size: 14px;
  padding: 9px 13px;
  min-height: 44px;
}
.mini-board {
  aspect-ratio: 1;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  border: 1px solid #6a7c64;
  overflow: hidden;
  border-radius: 3px;
  position: relative;
}
.mini-square {
  display: grid;
  place-items: center;
  background: #e9e3d1;
}
.mini-square.dark {
  background: #82967a;
}
.mini-square img {
  width: 92%;
  height: 92%;
  object-fit: contain;
}
.lab-column {
  padding: 28px 20px 30px;
  position: sticky;
  top: 0;
  max-height: 100dvh;
  overflow-y: auto;
  overscroll-behavior: contain;
}
.lab {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 9px;
  overflow: hidden;
}
.lab-head {
  padding: 18px 16px 12px;
  display: flex;
  justify-content: space-between;
  gap: 8px;
  align-items: start;
}
.lab-head .eyebrow {
  font-size: 11px;
  margin-bottom: 7px;
}
.lab-title {
  font-family: Georgia, serif;
  font-size: 23px;
  line-height: 1.2;
  margin: 0;
}
.lab-head .icon-button {
  border: 0;
  flex-shrink: 0;
}
.board-wrap {
  padding: 0 14px;
}
.board {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  aspect-ratio: 1;
  position: relative;
  border-radius: 3px;
  overflow: hidden;
  border: 1px solid #687b60;
  background: #82967a;
}
.square {
  position: relative;
  min-width: 0;
  min-height: 0;
  aspect-ratio: 1;
  padding: 0;
  border: 0;
  border-radius: 0;
  background: #e9e3d1;
  display: grid;
  place-items: center;
  cursor: default;
}
.square.dark {
  background: #82967a;
}
.square:hover {
  background: #e9e3d1;
}
.square.dark:hover {
  background: #82967a;
}
.square img {
  width: 89%;
  height: 89%;
  pointer-events: none;
  filter: drop-shadow(0 1px 1px #0002);
}
.square .coord {
  font:
    600 10px system-ui,
    sans-serif;
  position: absolute;
  left: 3px;
  top: 1px;
  color: #244529;
  z-index: 1;
}
.square.dark .coord {
  color: #152b1c;
}
.square .coord.file {
  top: auto;
  left: auto;
  right: 3px;
  bottom: 0;
}
.square.last {
  background: #d4ce78;
}
.square.dark.last {
  background: #aab86b;
}
.square.selected {
  box-shadow: inset 0 0 0 4px #c28135;
}
.square.legal:after {
  content: "";
  width: 26%;
  height: 26%;
  border-radius: 50%;
  background: #264b476e;
  position: absolute;
}
.square.legal:has(img):after {
  width: 84%;
  height: 84%;
  border: 5px solid #264b4770;
  background: transparent;
}
.board.exploring .square {
  cursor: pointer;
}
.square:focus-visible {
  outline: 3px solid #eea137;
  outline-offset: -3px;
  z-index: 3;
}
.square .marker {
  position: absolute;
  font-size: 18px;
  font-weight: 700;
  color: #a34f21;
}
.concept-frontier:after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 3px;
  background: #d18236;
  pointer-events: none;
}
.concept-centre:after {
  content: "";
  position: absolute;
  top: 37.5%;
  left: 37.5%;
  width: 25%;
  height: 25%;
  border: 3px solid #d18236;
  pointer-events: none;
}
.board-status {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--muted);
  padding: 9px 1px 0;
  min-height: 29px;
}
.turn-dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border: 1px solid #60705f;
  background: #fff;
  border-radius: 50%;
  margin-right: 6px;
}
.turn-dot.black {
  background: #25352c;
}
.board-controls {
  display: flex;
  gap: 7px;
  padding: 13px 14px;
}
.board-controls button {
  flex: 1;
  display: grid;
  place-items: center;
  min-width: 0;
  padding: 10px 5px;
}
.board-controls .play {
  flex: 1.5;
}
.annotation {
  padding: 0 16px 17px;
  font-size: 16px;
  line-height: 1.6;
  max-height: 240px;
  overflow: auto;
  white-space: pre-line;
}
.annotation .annotation-label {
  font-size: 11px;
  text-transform: uppercase;
  font-weight: 650;
  letter-spacing: 0.08em;
  color: var(--gold);
  display: block;
  margin-bottom: 7px;
}
.annotation p {
  margin-bottom: 0;
}
.annotation details {
  margin-top: 12px;
}
.annotation summary {
  cursor: pointer;
  min-height: 44px;
  padding: 10px 0;
}
.move-list {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 12px;
  max-height: 170px;
  overflow: auto;
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
  scroll-behavior: auto;
}
.move-list button {
  border: 0;
  min-height: 44px;
  padding: 8px 10px;
  background: transparent;
  font-size: 15px;
}
.move-list button.active {
  background: var(--green);
  color: white;
}
.move-list .number {
  color: var(--muted);
  margin-right: 5px;
  font-size: 13px;
}
.move-list button.active .number {
  color: #dfe8dc;
}
.lab-aux {
  display: flex;
  flex-wrap: wrap;
  padding: 12px 14px;
  gap: 8px;
}
.lab-aux button {
  flex: 1;
  min-width: 70px;
  padding: 10px 8px;
  font-size: 14px;
}
.lab-context {
  font-size: 14px;
  color: var(--muted);
  line-height: 1.65;
  padding: 15px 4px;
}
.lab-context p {
  margin-bottom: 10px;
}
.lab-context a {
  display: inline-block;
  min-height: 44px;
  padding: 10px 0;
}
.lab-select {
  width: 100%;
  margin-bottom: 12px;
  font-size: 15px;
}
.study-layout {
  display: grid;
  grid-template-columns: 1fr 460px;
  gap: 60px;
  align-items: start;
  max-width: 1140px;
  margin: auto;
}
.study-layout .lab-column {
  padding: 0;
  top: 20px;
  max-height: calc(100dvh - 40px);
}
.study-layout h1 {
  font-size: 53px;
  letter-spacing: -0.035em;
}
.study-list {
  display: grid;
  gap: 10px;
  margin-top: 28px;
}
.study-item {
  padding: 17px 20px;
  text-align: left;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.study-item.active {
  border-color: var(--green);
  background: var(--pale);
}
.study-item small {
  display: block;
  color: var(--muted);
  font-size: 14px;
  margin-top: 7px;
}
.tip {
  background: var(--pale);
  border-left: 3px solid var(--green);
  padding: 20px;
  margin: 24px 0;
  line-height: 1.65;
  font-size: 17px;
}
.tip strong {
  display: block;
  margin-bottom: 6px;
}
.chapter-end {
  display: flex;
  gap: 15px;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid var(--line);
  padding-top: 24px;
  margin-top: 40px;
}
.chapter-end button,
.chapter-end a {
  font-size: 15px;
}
.footer {
  margin-top: 65px;
  padding-top: 25px;
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 15px;
  color: var(--muted);
  font-size: 14px;
}
.footer a {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
}
.footer p {
  margin: 0;
}
.mobile-reader-tabs,
.mobile-contents {
  display: none;
}
.reading-progress {
  height: 3px;
  background: var(--line);
}
.reading-progress span {
  display: block;
  height: 100%;
  background: var(--green);
  width: 0;
}
.about {
  max-width: 800px;
}
.about h2 {
  font-size: 31px;
  margin: 45px 0 20px;
}
.about p,
.about li {
  font-size: 19px;
  line-height: 1.75;
}
.about li {
  margin-bottom: 12px;
}
.about a {
  color: var(--green);
}
.about table {
  border-collapse: collapse;
  width: 100%;
  font-size: 16px;
  line-height: 1.5;
}
.about th,
.about td {
  padding: 14px;
  text-align: left;
  border-bottom: 1px solid var(--line);
}
.badge {
  display: inline-block;
  font-size: 12px;
  padding: 5px 8px;
  background: var(--pale);
  border-radius: 4px;
  color: var(--green);
}
dialog {
  max-width: 620px;
  width: calc(100% - 32px);
  max-height: 85dvh;
  overflow: auto;
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  border-radius: 12px;
  padding: 28px;
  box-shadow: var(--shadow);
}
dialog::backdrop {
  background: #17291fcc;
  backdrop-filter: blur(3px);
}
.dialog-heading {
  display: flex;
  gap: 15px;
  justify-content: space-between;
  align-items: start;
  margin-bottom: 25px;
}
.dialog-heading h2 {
  font-size: 34px;
  margin: 0;
}
.dialog-heading .icon-button {
  font-size: 25px;
  flex-shrink: 0;
}
fieldset {
  border: 0;
  margin: 20px 0;
  padding: 0;
}
legend {
  margin-bottom: 14px;
  font-weight: 650;
}
.choice-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}
.choice-row button[aria-pressed="true"] {
  background: var(--green);
  color: white;
  border-color: var(--green);
}
.search-dialog input {
  width: 100%;
  margin-top: 12px;
}
.search-dialog label {
  color: var(--muted);
  font-size: 15px;
}
.search-dialog #search-count {
  font-size: 14px;
  color: var(--muted);
  margin: 14px 0;
}
.search-result {
  display: block;
  text-decoration: none;
  border-top: 1px solid var(--line);
  padding: 17px 0;
}
.search-result strong {
  font-size: 17px;
  font-weight: 600;
}
.search-result p {
  font-size: 15px;
  margin: 8px 0 0;
  color: var(--muted);
}
mark {
  background: #e3c683;
  color: #25352c;
  padding: 0 2px;
}
.toast {
  position: fixed;
  left: 50%;
  bottom: 25px;
  transform: translateX(-50%);
  padding: 14px 22px;
  max-width: calc(100% - 30px);
  background: var(--ink);
  color: var(--paper);
  border-radius: 8px;
  box-shadow: var(--shadow);
  z-index: 50;
  display: none;
  font-size: 16px;
}
.toast.visible {
  display: block;
}
.loading {
  display: grid;
  place-items: center;
  gap: 20px;
  min-height: 60vh;
}
.empty {
  padding: 35px 0;
  color: var(--muted);
}
.hidden {
  display: none !important;
}
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
.promotion-options {
  display: flex;
  gap: 10px;
}
.promotion-options img {
  width: 45px;
  height: 45px;
}
[data-theme="night"] {
  --paper: #18221d;
  --surface: #202d25;
  --ink: #e9ecdf;
  --muted: #b6c0b1;
  --line: #3d4a3f;
  --green: #b6d3a6;
  --pale: #2d3d30;
  --gold: #e2ad74;
  --shadow: 0 18px 55px #0004;
  color-scheme: dark;
}
[data-theme="night"] .primary,
[data-theme="night"] .brand-mark,
[data-theme="night"] .move-list button.active,
[data-theme="night"] .choice-row button[aria-pressed="true"] {
  color: #17271c;
}
[data-theme="night"] .primary:hover {
  background: #cfdfc2;
  color: #17271c;
}
@media (min-width: 1600px) {
  .reader-shell {
    grid-template-columns: 250px minmax(0, 1fr) 460px;
  }
  .lab-column {
    padding: 28px;
  }
  .reader-content {
    padding-left: 70px;
    padding-right: 70px;
  }
}
@media (max-width: 1200px) {
  .reader-shell {
    grid-template-columns: 190px minmax(0, 1fr) 345px;
  }
  .toc {
    padding: 25px 12px;
    font-size: 14px;
  }
  .reader-content {
    padding: 30px 28px;
  }
  .lab-column {
    padding: 25px 12px;
  }
  .hero {
    gap: 40px;
  }
  .diagram-card {
    grid-template-columns: 120px 1fr;
    padding: 16px;
    gap: 16px;
  }
  .lab-title {
    font-size: 21px;
  }
}
@media (max-width: 1000px) {
  .reader-shell {
    grid-template-columns: minmax(0, 1fr) 370px;
  }
  .toc {
    display: none;
  }
  .mobile-contents {
    display: block;
    margin-bottom: 25px;
  }
  .mobile-contents select {
    width: 100%;
    font-size: 16px;
  }
  .chapter-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .page-shell {
    padding: 38px 30px;
  }
  .hero {
    gap: 30px;
  }
  .hero h1 {
    font-size: 53px;
  }
  .hero .intro {
    font-size: 18px;
  }
  .study-layout {
    gap: 30px;
    grid-template-columns: 1fr 400px;
  }
  .topbar {
    gap: 20px;
    padding: 0 25px;
  }
  .topbar nav {
    gap: 20px;
  }
  .topbar nav a {
    font-size: 15px;
  }
  .stats-row {
    gap: 16px;
  }
  .stat {
    display: block;
  }
  .stat span {
    display: block;
    margin-top: 5px;
  }
  .study-layout h1 {
    font-size: 42px;
  }
}
@media (max-width: 760px) {
  .topbar {
    height: 74px;
    padding: 0 18px;
    gap: 10px;
  }
  .brand {
    font-size: 24px;
    gap: 9px;
  }
  .brand small {
    font-size: 9px;
    letter-spacing: 0.12em;
  }
  .brand-mark {
    width: 36px;
    height: 42px;
    font-size: 29px;
  }
  .topbar nav {
    display: none;
  }
  .header-actions {
    margin-left: auto;
    gap: 0;
  }
  .page-shell {
    padding: 32px 22px;
  }
  .hero {
    grid-template-columns: 1fr;
    padding-top: 6px;
    gap: 25px;
  }
  .hero h1 {
    font-size: 54px;
    max-width: 500px;
    margin-bottom: 22px;
  }
  .hero .intro {
    font-size: 19px;
  }
  .hero-actions {
    margin: 24px 0;
  }
  .hero-board {
    max-width: 410px;
    transform: none;
  }
  .hero-board .annotation {
    min-height: 85px;
  }
  .home-note {
    margin-top: 17px;
  }
  .stats-row {
    padding: 21px 0;
    margin-bottom: 30px;
    gap: 12px;
  }
  .stat b {
    font-size: 28px;
  }
  .stat span {
    font-size: 13px;
    line-height: 1.4;
  }
  .section-heading {
    align-items: start;
    gap: 15px;
  }
  .section-heading h2 {
    font-size: 30px;
  }
  .section-heading .text-link {
    font-size: 14px;
    white-space: nowrap;
  }
  .chapter-grid {
    gap: 12px;
  }
  .chapter-card {
    padding: 20px;
    min-height: 190px;
  }
  .chapter-card h3 {
    font-size: 23px;
  }
  .chapter-card .card-meta {
    display: block;
    font-size: 13px;
  }
  .chapter-card .card-meta span {
    display: block;
  }
  .page-heading h1 {
    font-size: 46px;
  }
  .page-heading p {
    font-size: 18px;
  }
  .game-grid {
    grid-template-columns: 1fr;
  }
  .resume {
    padding: 18px;
    align-items: start;
    flex-direction: column;
  }
  .reader-shell {
    display: block;
  }
  .reader-content {
    border: 0;
    padding: 25px 23px 45px;
  }
  .reader-title {
    font-size: 40px;
  }
  .reader-topline {
    margin-bottom: 22px;
  }
  .reader-topline .eyebrow {
    font-size: 12px;
    letter-spacing: 0.1em;
  }
  .mobile-reader-tabs {
    display: flex;
    position: sticky;
    top: 0;
    background: var(--paper);
    z-index: 8;
    border-bottom: 1px solid var(--line);
    padding: 8px 20px;
    gap: 8px;
  }
  .mobile-reader-tabs button {
    flex: 1;
    background: transparent;
    border-color: transparent;
    font-size: 15px;
  }
  .mobile-reader-tabs button[aria-pressed="true"] {
    background: var(--pale);
    color: var(--green);
  }
  .reader-shell .lab-column {
    display: none;
    padding: 20px 20px 35px;
    position: static;
    max-height: none;
    overflow: visible;
  }
  .reader-shell.show-board .reader-content {
    display: none;
  }
  .reader-shell.show-board .lab-column {
    display: block;
    max-width: 470px;
    margin: auto;
  }
  .lab-title {
    font-size: 24px;
  }
  .board-wrap {
    padding: 0 17px;
  }
  .board-controls {
    padding: 14px 17px;
  }
  .annotation {
    max-height: none;
    font-size: 17px;
    padding: 0 18px 20px;
  }
  .move-list {
    max-height: 150px;
  }
  .lab-aux button {
    font-size: 15px;
  }
  .board-status {
    font-size: 14px;
    padding-top: 11px;
  }
  .square .coord {
    font-size: 11px;
  }
  .diagram-card {
    grid-template-columns: 130px 1fr;
    gap: 18px;
    padding: 17px;
    margin: 26px 0;
  }
  .diagram-card p {
    font-size: 15px;
  }
  .study-layout {
    grid-template-columns: 1fr;
    gap: 25px;
  }
  .study-layout .lab-column {
    position: static;
    max-height: none;
    max-width: 460px;
    width: 100%;
    margin: auto;
    grid-row: 2;
  }
  .study-layout h1 {
    font-size: 43px;
  }
  .study-list {
    max-height: 300px;
    overflow: auto;
  }
  .study-layout .tip {
    margin-bottom: 0;
  }
  .study-layout .study-intro p {
    font-size: 18px;
  }
  .study-item {
    padding: 13px 15px;
    font-size: 16px;
  }
  .footer {
    margin-top: 40px;
  }
  .about p,
  .about li {
    font-size: 18px;
  }
  .about table {
    font-size: 14px;
  }
  .chapter-end {
    flex-wrap: wrap;
  }
  .chapter-end .button-link {
    flex: 1;
  }
  .chapter-summary {
    font-size: 15px;
  }
  .prose {
    line-height: 1.75;
  }
  .prose table {
    font-size: 17px;
  }
  dialog {
    padding: 24px;
  }
  .dialog-heading h2 {
    font-size: 30px;
  }
  .choice-row button {
    font-size: 15px;
  }
}
@media (max-width: 390px) {
  .page-shell {
    padding: 28px 18px;
  }
  .hero h1 {
    font-size: 47px;
  }
  .chapter-grid {
    grid-template-columns: 1fr;
  }
  .chapter-card {
    min-height: 155px;
  }
  .chapter-card h3 {
    margin: 12px 0 20px;
  }
  .diagram-card {
    grid-template-columns: 105px 1fr;
    padding: 14px;
    gap: 15px;
  }
  .reader-content {
    padding: 25px 20px;
  }
  .reader-title {
    font-size: 36px;
  }
  .brand small {
    display: none;
  }
  .header-actions .icon-button {
    min-width: 44px;
    padding: 9px;
  }
  .hero-actions .button-link {
    flex: 1;
    padding: 12px 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  *,
  *:before,
  *:after {
    scroll-behavior: auto !important;
    transition: none !important;
    animation: none !important;
  }
}
@media print {
  .topbar,
  .toc,
  .lab-column,
  .mobile-reader-tabs,
  .reader-tools,
  .chapter-end,
  .mobile-contents,
  .skip,
  .footer {
    display: none !important;
  }
  .reader-shell {
    display: block;
  }
  .reader-content {
    border: 0;
    padding: 0;
  }
  .prose {
    font-size: 12pt;
  }
  .diagram-card {
    break-inside: avoid;
  }
  body {
    background: white;
    color: black;
  }
}
.board-overlay {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 2;
  fill: none;
  stroke: #b06d31;
  stroke-width: 0.055;
}
.mini-board .board-overlay {
  stroke-width: 0.075;
}

.line-choice {
  padding: 0 14px;
}
.lab-head .eyebrow,
.annotation .annotation-label {
  font-size: 12px;
}

.lab[data-static="true"] .board-controls {
  display: none;
}
.lab[data-static="true"] .annotation {
  padding-top: 18px;
}
.source-passage {
  font-size: 16px;
  line-height: 1.65;
  padding: 12px 4px;
}
.source-passage summary {
  cursor: pointer;
  min-height: 44px;
  padding: 10px 0;
}
.source-passage p {
  white-space: pre-line;
  margin: 10px 0 16px;
}
.source-passage a {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
}
.hero-board .source-passage,
.hero-board .line-choice {
  display: none;
}

/* Prose examples get a board at the point of reading, including on a phone. */
.passage-replays {
  font-family:
    system-ui,
    -apple-system,
    sans-serif;
  margin: 0 0 2.2rem;
  border: 1px solid var(--line);
  border-left: 3px solid var(--green);
  border-radius: 8px;
  background: var(--surface);
  overflow: hidden;
  font-size: 17px;
  line-height: 1.5;
}
.passage-replays .passage-invitation {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0;
  padding: 16px 18px 8px;
  font-size: 16px;
  font-weight: 650;
  color: var(--green);
}
.passage-options {
  padding: 4px 12px 12px;
}
.passage-choice {
  display: block;
  width: 100%;
  text-align: left;
  margin: 5px 0 0;
  white-space: normal;
  overflow-wrap: anywhere;
}
.passage-choice span {
  display: block;
  font-size: 18px;
  font-weight: 600;
}
.passage-choice small {
  display: block;
  font-size: 14px;
  color: var(--muted);
  margin: 4px 0 8px;
}
.passage-choice b {
  font-size: 15px;
  color: var(--green);
}
.passage-choice.active {
  background: var(--pale);
  border-color: var(--green);
}
.passage-player {
  padding: 16px;
  border-top: 1px solid var(--line);
  scroll-margin-top: 90px;
}
.inline-player-head {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  justify-content: space-between;
}
.inline-player-head p {
  margin: 0 0 14px;
  line-height: 1.4;
}
.inline-player-head strong {
  display: block;
  font-family: Georgia, serif;
  font-size: 24px;
  font-weight: 500;
}
.inline-player-head p span {
  display: block;
  font-size: 15px;
  margin-top: 8px;
  color: var(--muted);
}
.inline-player-head .icon-button {
  flex-shrink: 0;
}
.inline-board {
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  width: 100%;
  max-width: 520px;
  aspect-ratio: 1;
  margin: 0 auto;
  position: relative;
  border: 1px solid #6d7c60;
  border-radius: 4px;
  overflow: hidden;
  isolation: isolate;
}
.inline-square {
  position: relative;
  display: grid;
  place-items: center;
  min-width: 0;
  background: #e9e5d0;
  aspect-ratio: 1;
}
.inline-square.dark {
  background: #87977b;
}
.inline-square.last {
  background: #d4ce78;
}
.inline-square.dark.last {
  background: #aab86b;
}
.inline-square img {
  width: 90%;
  height: 90%;
  object-fit: contain;
  z-index: 1;
}
.inline-square .coord {
  position: absolute;
  top: 0;
  left: 2px;
  color: #152b1c;
  font-size: clamp(10px, 1vw, 13px);
  font-weight: 700;
  line-height: 1;
  z-index: 3;
}
.inline-square .coord.file {
  top: auto;
  left: auto;
  right: 2px;
  bottom: 1px;
}
.inline-arrows {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 2;
}
.inline-arrows line {
  stroke-width: 0.12;
  stroke-linecap: round;
}
.inline-arrows .move-arrow {
  stroke: #21513e;
  opacity: 0.7;
}
#move-arrowhead {
  fill: #21513e;
}
.inline-arrows .threat-arrow {
  stroke: #bd4a09;
  stroke-width: 0.15;
}
#threat-arrowhead {
  fill: #bd4a09;
}
.inline-controls {
  display: flex;
  gap: 7px;
  margin: 12px 0 16px;
}
.inline-controls button {
  flex: 1;
  min-width: 0;
  padding: 10px 4px;
  display: grid;
  place-items: center;
}
.inline-controls [data-inline-action="play"] {
  flex: 1.35;
  background: var(--green);
  color: white;
}
.inline-explanation {
  font-size: max(18px, calc(var(--reader-size) - 2px));
}
.inline-explanation p {
  line-height: 1.6;
  margin: 0 0 12px;
}
.inline-explanation .plain-move {
  font-weight: 650;
}
.inline-explanation .inline-original {
  font-size: 15px;
  color: var(--muted);
}
.inline-explanation .annotation-label {
  display: block;
  color: var(--gold);
  font-size: 12px;
  letter-spacing: 0.05em;
  font-weight: 650;
  text-transform: uppercase;
  margin-bottom: 6px;
}
.inline-explanation blockquote {
  margin: 12px 0;
  padding: 12px 15px;
  border-left: 3px solid var(--line);
  background: var(--pale);
  font-family: Georgia, serif;
  font-size: var(--reader-size);
  line-height: 1.6;
}
.inline-explanation blockquote .annotation-label {
  color: var(--green);
}
.inline-moves {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  max-height: 170px;
  overflow: auto;
  position: relative;
  padding: 10px 0;
  border-top: 1px solid var(--line);
}
.inline-moves button {
  padding: 8px 10px;
  border-color: transparent;
  font-size: 16px;
  min-height: 44px;
}
.inline-moves [aria-current="step"] {
  background: var(--green);
  color: white;
}
.inline-footer {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 12px 0;
}
.inline-footer button {
  flex: 1;
  min-width: 110px;
  font-size: 15px;
}
.inline-source {
  font-size: 16px;
  color: var(--muted);
}
.inline-source summary {
  cursor: pointer;
  padding: 12px 0;
  min-height: 44px;
}
.inline-source p {
  white-space: pre-line;
  margin: 0 0 12px;
}
.passage-study-note {
  margin-top: 15px;
}
@media (max-width: 760px) {
  .passage-player {
    padding: 12px;
  }
  .inline-player-head strong {
    font-size: 22px;
  }
  .inline-explanation {
    font-size: max(18px, calc(var(--reader-size) - 2px));
  }
  .passage-replays .passage-invitation {
    padding: 14px 12px 8px;
  }
}