@font-face {
  font-family: "Source Serif 4 Variable";
  font-style: normal;
  font-weight: 200 900;
  font-display: swap;
  src: url("assets/fonts/source-serif-4-latin-variable.woff2") format("woff2");
}

@font-face {
  font-family: "Source Serif 4 Variable";
  font-style: italic;
  font-weight: 200 900;
  font-display: swap;
  src: url("assets/fonts/source-serif-4-latin-variable-italic.woff2") format("woff2");
}

:root {
  color-scheme: light;
  --paper: #ffffff;
  --paper-raised: #ffffff;
  --ink: #171716;
  --muted: #68665f;
  --faint: #6e6b63;
  --line: #d5d0c5;
  --line-strong: #77746b;
  --highlight: #fff4c2;
  --serif: "Source Serif 4 Variable", ui-serif, "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif;
  --sans: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --sidebar-width: 18.5rem;
  --measure: 43rem;
  --page-gutter: clamp(1.125rem, 5vw, 5.5rem);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  background: var(--paper);
  scroll-behavior: smooth;
  scroll-padding-top: 2rem;
}

body {
  margin: 0;
  min-width: 20rem;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.025rem, 0.98rem + 0.22vw, 1.16rem);
  font-kerning: normal;
  font-optical-sizing: auto;
  font-variant-numeric: oldstyle-nums proportional-nums;
  line-height: 1.68;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
  text-decoration-color: var(--line-strong);
  text-decoration-thickness: 0.07em;
  text-underline-offset: 0.18em;
}

a:hover {
  text-decoration-color: currentColor;
}

a:focus-visible,
button:focus-visible,
[tabindex="0"]:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 4px;
}

button {
  color: inherit;
  font: inherit;
}

main {
  background: var(--paper);
}

main:focus {
  outline: none;
}

.js-only {
  display: none;
}

.js .js-only {
  display: inline-flex;
}

.no-js-only,
.js .no-js-only,
.no-js .js-only {
  display: none;
}

.no-js .no-js-only {
  display: inline-flex;
}

.pdf-only {
  display: none;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.75rem;
  left: 0.75rem;
  padding: 0.55rem 0.75rem;
  transform: translateY(-180%);
  background: var(--ink);
  color: var(--paper-raised);
  font-family: var(--sans);
  font-size: 0.82rem;
}

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

.reading-progress {
  position: fixed;
  z-index: 90;
  inset: 0 0 auto;
  height: 2px;
  background: transparent;
}

.reading-progress span {
  display: block;
  width: calc(var(--reading-progress, 0) * 1%);
  height: 100%;
  background: var(--ink);
  transition: width 100ms linear;
}

.book-shell {
  display: grid;
  grid-template-columns: var(--sidebar-width) minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  display: flex;
  flex-direction: column;
  height: 100vh;
  border-right: 1px solid var(--line);
  background: color-mix(in srgb, var(--paper) 94%, white);
  font-family: var(--sans);
}

.sidebar-brand {
  display: block;
  padding: 2rem 1.75rem 1.65rem;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
}

.sidebar-brand span {
  display: block;
  color: var(--muted);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1.3;
  text-transform: uppercase;
}

.sidebar-brand strong {
  display: block;
  margin-top: 0.2rem;
  font-family: var(--serif);
  font-size: 1.45rem;
  font-weight: 500;
  line-height: 1.1;
}

.sidebar-nav {
  min-height: 0;
  padding: 1.45rem 0.9rem 2rem;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
}

.nav-label,
.section-label,
.chapter-kicker {
  margin: 0;
  font-family: var(--sans);
  font-size: 0.7rem;
  font-weight: 650;
  letter-spacing: 0.12em;
  line-height: 1.3;
  text-transform: uppercase;
}

.nav-label {
  padding: 0 0.8rem 0.65rem;
  color: var(--muted);
}

.sidebar-nav ol,
.toc-dialog ol,
.contents-page ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

.sidebar-nav a {
  display: grid;
  grid-template-columns: 2rem 1fr;
  gap: 0.25rem;
  align-items: baseline;
  padding: 0.48rem 0.72rem;
  border-radius: 2px;
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.3;
  text-decoration: none;
}

.sidebar-nav small {
  display: none;
}

.sidebar-nav .toc-page {
  display: none;
}

.sidebar-nav a:hover,
.sidebar-nav a[aria-current="location"] {
  background: rgba(23, 23, 22, 0.055);
  color: var(--ink);
}

.toc-number {
  color: var(--faint);
  font-variant-numeric: tabular-nums;
}

.sidebar-meta {
  display: grid;
  gap: 0.75rem;
  padding: 1rem 1.7rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.72rem;
}

.sidebar-meta p {
  margin: 0;
}

.sidebar-publication {
  display: grid;
  gap: 0.35rem;
}

.sidebar-author {
  color: var(--ink);
  font-size: 0.82rem;
  line-height: 1.4;
}

.sidebar-edition {
  font-size: 0.72rem;
  font-variant-numeric: tabular-nums;
  line-height: 1.4;
}

.sidebar-actions {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.text-button,
.text-link,
.menu-button,
.dialog-close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.75rem;
  padding: 0.25rem;
  border: 0;
  background: transparent;
  cursor: pointer;
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}

.text-button,
.text-link {
  text-decoration: underline;
  text-decoration-color: var(--line-strong);
  text-underline-offset: 0.2em;
}

main {
  min-width: 0;
}

.cover,
.foreword,
.contents-page,
.chapter,
.back-matter,
.book-footer {
  width: min(100%, calc(var(--measure) + 2 * var(--page-gutter)));
  margin-inline: auto;
  padding-inline: var(--page-gutter);
}

.cover {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-height: 100svh;
  padding-block: clamp(5rem, 12vh, 9rem);
  border-bottom: 1px solid var(--line);
}

.cover-rule {
  width: 4rem;
  height: 1px;
  margin-bottom: clamp(3rem, 9vh, 7rem);
  background: var(--ink);
}

.cover h1 {
  max-width: 11ch;
  margin: 1.4rem 0 1.2rem;
  font-size: clamp(3.3rem, 7.5vw, 7.8rem);
  font-weight: 400;
  letter-spacing: -0.055em;
  line-height: 0.93;
}

.cover-subtitle {
  max-width: 35rem;
  margin: 0;
  color: var(--muted);
  font-size: clamp(1.1rem, 1rem + 0.65vw, 1.55rem);
  font-style: italic;
  line-height: 1.45;
}

.cover-credit {
  margin: clamp(3rem, 7vh, 5.5rem) 0 0;
  font-family: var(--sans);
  font-size: 0.82rem;
}

.cover-date {
  margin: clamp(1.75rem, 3vh, 2.5rem) 0 0;
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.72rem;
  font-variant-numeric: lining-nums tabular-nums;
  letter-spacing: 0.02em;
}

.release-window {
  width: min(100%, 34rem);
  margin-top: clamp(1.5rem, 3vh, 2.25rem);
  padding-block: 0.85rem 1rem;
  border-block: 1px solid var(--line);
  font-family: var(--sans);
}

.release-window p {
  margin: 0;
}

.release-window-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
}

.release-window-label,
.release-window-products {
  color: var(--ink);
  font-size: 0.66rem;
  font-weight: 650;
  letter-spacing: 0.12em;
  line-height: 1.3;
  text-transform: uppercase;
}

.release-window-products {
  color: var(--muted);
  font-weight: 500;
  white-space: nowrap;
}

.js .release-countdown {
  display: grid;
}

.release-countdown {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-block: 0.85rem 0.7rem;
}

.release-countdown[hidden] {
  display: none !important;
}

.release-countdown > span {
  display: grid;
  gap: 0.2rem;
  min-width: 0;
  padding-inline: 0.75rem;
  border-left: 1px solid var(--line);
}

.release-countdown > span:first-child {
  padding-left: 0;
  border-left: 0;
}

.release-countdown strong {
  font-size: clamp(1.35rem, 3vw, 1.75rem);
  font-variant-numeric: lining-nums tabular-nums;
  font-weight: 500;
  letter-spacing: -0.035em;
  line-height: 1;
}

.release-countdown small {
  color: var(--muted);
  font-size: 0.58rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  line-height: 1.2;
  text-transform: uppercase;
}

.release-window-schedule,
.release-window-policy {
  color: var(--muted);
  font-size: 0.7rem;
  line-height: 1.45;
}

.release-window-policy {
  margin-top: 0.2rem !important;
}

.release-window.is-review-open {
  border-color: var(--line-strong);
}

.cover-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: clamp(1.5rem, 3vh, 2.25rem);
  font-family: var(--sans);
}

.action-link {
  display: inline-flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.25rem;
  min-height: 2.75rem;
  padding: 0.65rem 0.8rem;
  border: 1px solid var(--ink);
  background: transparent;
  color: var(--ink);
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.045em;
  line-height: 1.25;
  text-decoration: none;
  text-transform: uppercase;
  white-space: nowrap;
}

.action-link:hover {
  background: rgba(23, 23, 22, 0.055);
}

.action-link-primary {
  background: var(--ink);
  color: var(--paper-raised);
}

.action-link-primary:hover {
  background: #30302e;
}

.action-link span {
  color: inherit;
  font-size: 0.62rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  opacity: 0.78;
  text-transform: none;
}

.source-note {
  margin: 2.5rem 0 0;
  color: var(--faint);
  font-size: 0.78rem;
}

.foreword,
.contents-page {
  padding-block: clamp(5rem, 10vw, 9rem);
}

.foreword {
  border-bottom: 1px solid var(--line);
}

.section-label,
.chapter-kicker {
  color: var(--muted);
}

.foreword h2,
.contents-page h2 {
  margin: 0.75rem 0 2rem;
  font-size: clamp(2.25rem, 5vw, 4.5rem);
  font-weight: 400;
  letter-spacing: -0.035em;
  line-height: 1;
}

.foreword > p:not(.section-label),
.foreword blockquote {
  max-width: var(--measure);
}

blockquote {
  margin: 2.5rem 0;
  padding: 0 0 0 clamp(1.25rem, 4vw, 2.5rem);
  border-left: 1px solid var(--ink);
}

blockquote p {
  margin: 0;
  font-size: clamp(1.35rem, 1.18rem + 0.7vw, 1.85rem);
  font-style: italic;
  line-height: 1.42;
}

.contents-page {
  min-height: 100svh;
}

.contents-page ol {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 2.75rem;
  margin-top: 3rem;
  border-top: 1px solid var(--ink);
}

.contents-page li {
  border-bottom: 1px solid var(--line);
}

.contents-page a {
  display: grid;
  grid-template-columns: 2.25rem minmax(0, 1fr) auto;
  gap: 0.5rem;
  align-items: baseline;
  padding: 0.85rem 0.5rem;
  font-size: 0.98rem;
  line-height: 1.3;
  text-decoration: none;
}

.contents-page a:hover,
.contents-page a:focus-visible {
  background: var(--highlight);
}

.toc-page {
  color: var(--faint);
  font-family: var(--sans);
  font-size: 0.7rem;
  font-variant-numeric: lining-nums tabular-nums;
  text-align: right;
}

.contents-page a:hover .toc-title,
.contents-page a:focus-visible .toc-title {
  text-decoration: underline;
  text-decoration-thickness: 0.06em;
  text-underline-offset: 0.2em;
}

.toc-title small {
  display: block;
  margin-top: 0.25rem;
  color: var(--faint);
  font-family: var(--sans);
  font-size: 0.62rem;
  font-weight: 500;
  letter-spacing: 0.035em;
  text-transform: uppercase;
}

.chapter {
  scroll-margin-top: 1.5rem;
  padding-block: clamp(5rem, 11vw, 10rem) clamp(4rem, 9vw, 8rem);
  border-top: 1px solid var(--line);
}

.chapter-header {
  margin-bottom: clamp(3rem, 7vw, 5.5rem);
  scroll-margin-top: 1.5rem;
}

.chapter-header h2 {
  max-width: 15ch;
  margin: 0.75rem 0 1.2rem;
  font-size: clamp(2.55rem, 6.2vw, 5.7rem);
  font-weight: 400;
  letter-spacing: -0.045em;
  line-height: 0.98;
  text-wrap: balance;
}

.chapter-deck {
  max-width: 35rem;
  margin: 0 0 clamp(2.5rem, 6vw, 4.5rem);
  color: var(--muted);
  font-size: clamp(1.12rem, 1.02rem + 0.42vw, 1.38rem);
  font-style: italic;
  line-height: 1.45;
  text-wrap: pretty;
}

.chapter-figure {
  margin: 0;
}

.chapter-art {
  display: block;
  width: min(100%, 30rem);
  height: auto;
  border: 0;
  background: transparent;
  clip-path: inset(2px);
  filter: grayscale(1) contrast(1.1) brightness(1.02);
}

#chapter-03-prefill-and-decode-are-different-jobs .chapter-art,
#chapter-09-trace-the-whole-user-journey .chapter-art {
  -webkit-mask-image: linear-gradient(to right, transparent 0, #000 7%, #000 100%);
  mask-image: linear-gradient(to right, transparent 0, #000 7%, #000 100%);
}

#chapter-05-turn-model-output-into-a-contract .chapter-art {
  -webkit-mask-image: radial-gradient(circle at 100% 0%, transparent 0, transparent 4%, #000 18%, #000 100%);
  mask-image: radial-gradient(circle at 100% 0%, transparent 0, transparent 4%, #000 18%, #000 100%);
}

.chapter-body {
  max-width: var(--measure);
}

.chapter-body > :first-child {
  margin-top: 0;
}

.chapter-body p {
  margin: 1.25em 0;
}

.source-section > h3 {
  margin: 0 0 1.5rem;
  font-size: clamp(1.85rem, 1.52rem + 1.1vw, 2.55rem);
  font-weight: 500;
  letter-spacing: -0.025em;
  line-height: 1.18;
}

.source-section > h3 .section-number {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.6em;
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  letter-spacing: 0.04em;
  vertical-align: 0.12em;
  white-space: nowrap;
}

.source-section + .source-section {
  margin-top: clamp(4rem, 9vw, 7rem);
  padding-top: clamp(3rem, 7vw, 5rem);
  border-top: 1px solid var(--line);
}

.citation-marker {
  margin-left: 0.12em;
  font-family: var(--sans);
  font-size: 0.62em;
  font-style: normal;
  font-variant-numeric: lining-nums tabular-nums;
  vertical-align: super;
  white-space: nowrap;
}

.citation-marker a {
  text-decoration: none;
}

.section-sources {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 0.45rem;
  align-items: baseline;
  margin-top: 2rem !important;
  padding-top: 0.75rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.7rem;
  font-variant-numeric: lining-nums tabular-nums;
  line-height: 1.45;
}

.section-sources strong {
  color: var(--ink);
  font-size: 0.64rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.section-sources span {
  flex-basis: 100%;
  font-family: var(--serif);
  font-style: italic;
}

.back-matter {
  padding-block: clamp(5rem, 10vw, 9rem);
  border-top: 1px solid var(--line);
}

.back-matter-header {
  max-width: var(--measure);
  margin-bottom: clamp(3rem, 7vw, 5rem);
}

.back-matter-header h2 {
  margin: 0.75rem 0 1.5rem;
  font-size: clamp(2.5rem, 5.5vw, 5rem);
  font-weight: 400;
  letter-spacing: -0.04em;
  line-height: 0.98;
}

.back-matter-header > p:not(.section-label) {
  max-width: 39rem;
  color: var(--muted);
}

.source-map,
.reference-group {
  max-width: var(--measure);
}

.source-map {
  margin-bottom: 4rem;
}

.source-map h3,
.reference-group h3 {
  margin: 0 0 1.1rem;
  font-size: 1.45rem;
  font-weight: 500;
  letter-spacing: -0.02em;
}

.source-map ol,
.reference-list,
.index-group ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.source-map li {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 0.25rem 1rem;
  padding: 0.65rem 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.86rem;
  line-height: 1.4;
}

.source-map-section {
  text-decoration: none;
}

.source-map-references {
  font-family: var(--sans);
  font-size: 0.68rem;
  font-variant-numeric: lining-nums tabular-nums;
  white-space: normal;
}

.source-map li > span:last-child:not(.source-map-references) {
  grid-column: 1 / -1;
  color: var(--muted);
  font-style: italic;
}

.reference-group + .reference-group {
  margin-top: 3.5rem;
}

.reference-list > li {
  display: grid;
  grid-template-columns: 5rem minmax(0, 1fr);
  gap: 1rem;
  padding: 0.8rem 0;
  border-top: 1px solid var(--line);
}

.reference-label {
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 650;
  font-variant-numeric: lining-nums tabular-nums;
}

.reference-list p {
  margin: 0;
  font-size: 0.88rem;
  line-height: 1.5;
}

.reference-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 1rem;
  margin-top: 0.25rem !important;
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.66rem !important;
}

.reference-meta a {
  overflow-wrap: anywhere;
}

.index-columns {
  column-count: 2;
  column-gap: 2.5rem;
}

.index-group {
  break-inside: auto;
}

.index-group h3 {
  margin: 1.5rem 0 0.45rem;
  border-bottom: 1px solid var(--ink);
  font-size: 1.1rem;
  font-weight: 500;
  break-after: avoid;
}

.index-group:first-child h3 {
  margin-top: 0;
}

.index-group li {
  margin: 0 0 0.48rem;
  padding-left: 1em;
  font-size: 0.82rem;
  line-height: 1.35;
  text-indent: -1em;
  break-inside: avoid;
}

.index-term {
  font-weight: 550;
}

.index-pages {
  margin-left: 0.32em;
  font-family: var(--sans);
  font-size: 0.8em;
  font-variant-numeric: lining-nums tabular-nums;
}

.index-pages::before {
  content: "· ";
  color: var(--faint);
}

.index-pages a,
.index-see a {
  text-decoration: none;
}

.index-see {
  display: block;
  padding-left: 1em;
  color: var(--muted);
  font-style: italic;
  text-indent: 0;
}

.changelog-entries {
  max-width: var(--measure);
  margin: 0;
}

.changelog-entry {
  padding: 1.4rem 0;
  border-top: 1px solid var(--line);
}

.changelog-entry:first-child {
  border-top-color: var(--line-strong);
}

.changelog-entry-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 0.7rem;
  margin: 0 0 0.55rem;
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.changelog-entry-meta a {
  color: inherit;
}

.changelog-entry h3 {
  margin: 0 0 1rem;
  font-family: var(--serif);
  font-size: 1.35rem;
  font-weight: 550;
  letter-spacing: -0.015em;
  line-height: 1.15;
}

.changelog-entry-part + .changelog-entry-part {
  margin-top: 0.9rem;
}

.changelog-entry-copy h4,
.changelog-sources strong {
  display: block;
  margin: 0 0 0.25rem;
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.changelog-entry-copy p,
.changelog-entry-copy ul {
  margin: 0;
}

.changelog-entry-copy ul {
  padding-left: 1.15rem;
}

.changelog-sources {
  margin: 1rem 0 0;
  font-family: var(--sans);
  font-size: 0.76rem;
  line-height: 1.45;
}

.changelog-sources a {
  overflow-wrap: anywhere;
}

.changelog-version {
  color: var(--ink) !important;
  font-family: var(--sans);
  font-size: 0.78rem;
  font-weight: 650;
}

.chapter-body h4 {
  margin: 3.2rem 0 1rem;
  font-family: var(--serif);
  font-size: clamp(1.45rem, 1.3rem + 0.6vw, 1.9rem);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.chapter-body h5,
.chapter-body h6 {
  margin: 2.5rem 0 0.85rem;
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.3;
}

.chapter-body ul,
.chapter-body ol {
  margin: 1.25rem 0;
  padding-left: 1.35em;
}

.chapter-body li {
  margin: 0.42em 0;
  padding-left: 0.35em;
}

.chapter-body li::marker {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.outline-list,
.outline-list ol {
  counter-reset: outline-item;
  list-style: none;
}

.chapter-body .outline-list {
  padding-left: 0;
}

.outline-list ol {
  margin: 0.25em 0 0.7em;
  padding-left: 0;
}

.outline-list li {
  position: relative;
  counter-increment: outline-item;
  padding-left: 2.25em;
}

.outline-list li::before {
  content: counters(outline-item, ".") ".";
  position: absolute;
  left: 0;
  width: 1.9em;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.outline-list > li {
  margin: 0.7em 0;
  break-inside: avoid-page;
}

.outline-list > li > .outline-entry {
  font-weight: 650;
}

.outline-list ol > li {
  margin: 0.24em 0;
}

.checklist {
  padding-left: 0 !important;
  list-style: none;
}

.checklist li {
  display: grid;
  grid-template-columns: 1rem 1fr;
  gap: 0.65rem;
  padding-left: 0;
}

.checklist-box {
  display: grid;
  place-items: center;
  width: 0.9rem;
  height: 0.9rem;
  margin: 0.42em 0 0;
  border: 1px solid var(--ink);
  font-family: var(--sans);
  font-size: 0.7rem;
  line-height: 1;
}

.checklist-box[data-checked="true"]::after {
  content: "✓";
}

strong {
  font-weight: 650;
}

code {
  font-family: var(--mono);
  font-size: 0.83em;
}

p code,
li code,
td code {
  padding: 0.08em 0.28em;
  border: 1px solid var(--line);
  border-radius: 2px;
  background: rgba(255, 255, 255, 0.35);
  overflow-wrap: anywhere;
}

.code-frame {
  margin: 2rem 0;
  border: 0;
  background: transparent;
}

.code-frame pre {
  padding: 0;
  line-height: 1.65;
}

.code-frame code {
  display: block;
  color: var(--ink);
}

.syntax-key {
  font-weight: 750;
}

.syntax-string {
  color: var(--muted);
}

.syntax-boolean,
.syntax-null {
  font-style: italic;
  font-weight: 650;
}

.syntax-null,
.syntax-punctuation {
  color: var(--muted);
}

.syntax-number {
  font-weight: 650;
  font-variant-numeric: lining-nums tabular-nums;
}

.editorial-example {
  margin: 2rem 0;
  font-family: var(--sans);
}

.key-value-example {
  border-block: 1px solid var(--ink);
}

.key-value-example > div {
  display: grid;
  grid-template-columns: minmax(8.75rem, 0.8fr) minmax(0, 1.55fr);
  gap: 1rem;
  padding: 0.68rem 0;
  border-bottom: 1px solid var(--line);
}

.key-value-example > div:last-child {
  border-bottom: 0;
}

.key-value-example dt {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.025em;
  line-height: 1.45;
}

.key-value-example dd {
  margin: 0;
  font-size: 0.84rem;
  line-height: 1.45;
}

.cache-key-composition {
  border-block: 1px solid var(--ink);
}

.cache-key-composition > div {
  display: grid;
  grid-template-columns: minmax(8.75rem, 0.8fr) minmax(0, 1.55fr);
  gap: 1rem;
  padding: 0.78rem 0;
  border-bottom: 1px solid var(--line);
}

.cache-key-composition > div:last-child {
  border-bottom: 0;
}

.cache-key-composition dt {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.055em;
  line-height: 1.45;
  text-transform: uppercase;
}

.cache-key-composition dd {
  display: flex;
  flex-wrap: wrap;
  gap: 0.28rem 0;
  margin: 0;
  font-size: 0.84rem;
  line-height: 1.45;
}

.cache-key-term {
  display: inline-flex;
  align-items: baseline;
}

.cache-key-term + .cache-key-term::before {
  margin: 0 0.48rem;
  color: var(--muted);
  content: "+";
  font-weight: 400;
}

.latency-budget {
  border-block: 1px solid var(--ink);
  font-family: var(--sans);
}

.latency-budget .latency-total {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.72rem 0;
  border-bottom: 1px solid var(--ink);
}

.latency-budget .latency-total strong {
  font-family: var(--serif);
  font-size: 1.08rem;
  font-weight: 550;
  letter-spacing: -0.01em;
}

.latency-budget .latency-total span {
  color: var(--muted);
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.latency-band {
  display: grid;
  grid-template-columns: minmax(8.75rem, 0.8fr) minmax(0, 1.55fr);
  gap: 1rem;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--line);
}

.latency-band:last-child {
  border-bottom: 0;
}

.latency-band > p {
  margin: 0;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.055em;
  line-height: 1.45;
  text-transform: uppercase;
}

.latency-band > div {
  display: flex;
  flex-wrap: wrap;
  gap: 0.28rem 0;
  font-size: 0.84rem;
  line-height: 1.45;
}

.latency-stage {
  display: inline-flex;
  align-items: baseline;
}

.latency-stage + .latency-stage::before {
  margin: 0 0.48rem;
  color: var(--muted);
  content: "+";
  font-weight: 400;
}

.kv-footprint,
.golden-record,
.trace-tree,
.cost-model {
  border-block: 1px solid var(--ink);
}

.kv-total,
.cost-total {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.72rem 0;
  border-bottom: 1px solid var(--ink);
}

.kv-total strong,
.cost-total strong {
  font-family: var(--serif);
  font-size: 1.08rem;
  font-weight: 550;
  letter-spacing: -0.01em;
}

.kv-total span,
.cost-total span {
  color: var(--muted);
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.kv-factors {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem 0;
  padding: 0.78rem 0;
}

.kv-factor {
  display: inline-flex;
  align-items: baseline;
  gap: 0.35rem;
  white-space: nowrap;
}

.kv-factor + .kv-factor::before {
  margin: 0 0.55rem;
  color: var(--muted);
  content: "×";
  font-weight: 400;
}

.kv-factor strong {
  font-size: 0.88rem;
  font-weight: 650;
}

.kv-factor small {
  color: var(--muted);
  font-size: 0.68rem;
  line-height: 1.35;
}

.golden-record > div,
.cost-model dl > div {
  display: grid;
  grid-template-columns: minmax(8.75rem, 0.8fr) minmax(0, 1.55fr);
  gap: 1rem;
  padding: 0.72rem 0;
}

.golden-record dt,
.cost-model dt {
  margin: 0;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.055em;
  line-height: 1.45;
  text-transform: uppercase;
}

.golden-record dd,
.cost-model dd {
  display: flex;
  flex-wrap: wrap;
  gap: 0.28rem 0;
  margin: 0;
  font-size: 0.84rem;
  line-height: 1.45;
}

.golden-record dd span,
.cost-model dd > span {
  display: inline-flex;
  align-items: baseline;
}

.golden-record > div,
.cost-model dl > div {
  border-bottom: 1px solid var(--line);
}

/* Paired data rows share one visual axis, even when either side wraps. */
.key-value-example > div,
.cache-key-composition > div,
.latency-band,
.golden-record > div,
.cost-model dl > div {
  align-items: center;
}

.golden-record > div:last-child,
.cost-model dl > div:last-child {
  border-bottom: 0;
}

.golden-record dd span + span::before {
  margin: 0 0.48rem;
  color: var(--muted);
  content: "•";
}

.trace-tree {
  padding: 0.72rem 0;
}

.trace-tree ul {
  margin: 0;
  padding-left: 1rem;
  list-style: none;
}

.trace-tree > ul {
  padding-left: 0;
}

.trace-tree ul ul {
  margin: 0.14rem 0 0.24rem 0.35rem;
  border-left: 1px solid var(--line);
}

.trace-tree li {
  position: relative;
  margin: 0.16rem 0;
  padding-left: 0;
  font-size: 0.8rem;
  line-height: 1.38;
}

.trace-tree ul ul > li {
  padding-left: 0.75rem;
}

.trace-tree ul ul > li::before {
  position: absolute;
  top: 0.7em;
  left: 0;
  width: 0.5rem;
  border-top: 1px solid var(--line);
  content: "";
}

.trace-tree > ul > li > span {
  font-family: var(--serif);
  font-size: 1.02rem;
  font-weight: 600;
}

.cost-model dl {
  margin: 0;
}

.cost-model dd > span + span::before {
  margin: 0 0.48rem;
  color: var(--muted);
  content: "+";
}

.cost-alternative {
  display: grid !important;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  gap: 0.45rem;
  width: 100%;
}

.cost-alternative em {
  color: var(--muted);
  font-family: var(--serif);
}

.cost-model > p {
  margin: 0 !important;
  padding: 0.72rem 0;
  border-top: 1px solid var(--ink);
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.45;
}

pre {
  margin: 0;
  padding: 1rem;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: clamp(0.72rem, 0.67rem + 0.16vw, 0.82rem);
  line-height: 1.55;
  overscroll-behavior-inline: contain;
  white-space: pre;
}

.system-flow-diagram {
  margin: 1.8rem 0 2.1rem;
  color: var(--ink);
}

.system-flow-diagram svg {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
  shape-rendering: geometricPrecision;
}

.system-flow-diagram .diagram-node rect {
  fill: transparent;
  stroke: currentColor;
  stroke-width: 0.95;
  vector-effect: non-scaling-stroke;
}

.system-flow-diagram .diagram-node-terminal rect {
  stroke-width: 1.35;
}

.system-flow-diagram text {
  fill: currentColor;
  font-family: var(--sans);
  font-size: 17px;
}

.system-flow-diagram .diagram-node-label,
.system-flow-diagram .diagram-group-label {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 1.45px;
}

.system-flow-diagram .diagram-node-detail,
.system-flow-diagram .diagram-edge-label {
  fill: var(--muted);
  font-size: 13px;
}

.system-flow-diagram .diagram-node-detail-tight {
  font-size: 12.25px;
}

.system-flow-diagram .diagram-edge-label {
  font-family: var(--serif);
  font-size: 14px;
  font-style: italic;
}

.system-flow-diagram .diagram-arrow {
  fill: none;
  stroke: currentColor;
  stroke-width: 1.05;
  marker-end: url(#system-flow-arrow);
  vector-effect: non-scaling-stroke;
}

.system-flow-diagram .diagram-branch {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.95;
  vector-effect: non-scaling-stroke;
}

.system-flow-diagram .diagram-loop {
  stroke-width: 0.9;
}

.system-flow-diagram .diagram-resource-link,
.system-flow-diagram .diagram-resource-collector {
  fill: none;
  stroke: var(--line-strong);
  stroke-width: 0.85;
  vector-effect: non-scaling-stroke;
}

.system-flow-diagram .diagram-resource-collector {
  marker-end: url(#system-flow-arrow);
}

.system-flow-diagram .diagram-resource {
  font-size: 14px;
}

.system-flow-diagram .diagram-control-line,
.system-flow-diagram .diagram-control-tick,
.system-flow-diagram .diagram-control-rail {
  fill: none;
  stroke: var(--muted);
  stroke-width: 0.8;
  stroke-dasharray: 4 4;
  vector-effect: non-scaling-stroke;
}

.system-flow-diagram .diagram-control-rule {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.85;
  vector-effect: non-scaling-stroke;
}

.system-flow-diagram .diagram-control {
  font-size: 14.5px;
}

.system-flow-diagram .diagram-control .diagram-node-detail {
  font-size: 13.5px;
}

.system-flow-diagram .diagram-arrowhead {
  fill: var(--ink);
}

.validation-flow-diagram {
  margin: 1.8rem 0 2.1rem;
  color: var(--ink);
}

.validation-flow-diagram svg {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
  shape-rendering: geometricPrecision;
}

.validation-flow-diagram text {
  fill: currentColor;
  font-family: var(--sans);
}

.validation-flow-diagram .validation-origin text {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 1.65px;
}

.validation-flow-diagram .validation-origin-rule,
.validation-flow-diagram .validation-step-tick {
  stroke: currentColor;
  stroke-width: 0.8;
  vector-effect: non-scaling-stroke;
}

.validation-flow-diagram .validation-step-number {
  fill: var(--muted);
  font-size: 11px;
  font-weight: 650;
  letter-spacing: 0.7px;
}

.validation-flow-diagram .validation-step-title {
  font-size: 18px;
  font-weight: 620;
}

.validation-flow-diagram .validation-step-detail {
  fill: var(--muted);
  font-size: 15px;
}

.validation-flow-diagram .validation-row-rule {
  stroke: var(--line-strong);
  stroke-width: 0.55;
  opacity: 0.72;
  vector-effect: non-scaling-stroke;
}

.validation-flow-diagram .validation-spine-link {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.8;
  vector-effect: non-scaling-stroke;
}

.fallback-flow-diagram {
  margin: 1.8rem 0 2.1rem;
  color: var(--ink);
}

.fallback-flow-diagram svg {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
  shape-rendering: geometricPrecision;
}

.fallback-flow-diagram text {
  fill: currentColor;
  font-family: var(--sans);
}

.fallback-flow-diagram .fallback-state-point,
.fallback-flow-diagram .fallback-terminal-point {
  fill: var(--paper);
  stroke: currentColor;
  stroke-width: 1;
  vector-effect: non-scaling-stroke;
}

.fallback-flow-diagram .fallback-primary .fallback-state-point {
  fill: currentColor;
}

.fallback-flow-diagram .fallback-terminal-point {
  stroke-width: 1.35;
}

.fallback-flow-diagram .fallback-state-label {
  font-size: 17px;
  font-weight: 560;
}

.fallback-flow-diagram .fallback-terminal-label {
  font-size: 14px;
  font-weight: 560;
}

.fallback-flow-diagram .fallback-qualifier,
.fallback-flow-diagram .fallback-branch-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.45px;
}

.fallback-flow-diagram .fallback-edge-label {
  fill: var(--muted);
  font-family: var(--serif);
  font-size: 14px;
  font-style: italic;
}

.fallback-flow-diagram .fallback-qualifier-rule {
  fill: none;
  stroke: var(--line-strong);
  stroke-width: 0.65;
  vector-effect: non-scaling-stroke;
}

.fallback-flow-diagram .fallback-arrow,
.fallback-flow-diagram .fallback-branch {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.95;
  vector-effect: non-scaling-stroke;
}

.fallback-flow-diagram .fallback-arrow {
  marker-end: url(#fallback-flow-arrow);
}

.fallback-flow-diagram .fallback-branch {
  stroke-width: 0.85;
}

.fallback-flow-diagram .fallback-branch-arrow {
  stroke-width: 0.85;
}

.fallback-flow-diagram .fallback-arrowhead {
  fill: var(--ink);
}

.rag-flow-diagram {
  margin: 1.8rem 0 2.1rem;
  color: var(--ink);
}

.rag-flow-diagram svg {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
  shape-rendering: geometricPrecision;
}

.rag-flow-diagram text {
  fill: currentColor;
  font-family: var(--sans);
}

.rag-flow-diagram .rag-lane-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.45px;
}

.rag-flow-diagram .rag-lane-rule,
.rag-flow-diagram .rag-stage-rule {
  stroke: var(--line-strong);
  stroke-width: 0.65;
  vector-effect: non-scaling-stroke;
}

.rag-flow-diagram .rag-stage-title {
  font-size: 16px;
  font-weight: 580;
}

.rag-flow-diagram .rag-datastore,
.rag-flow-diagram .rag-datastore-rim {
  fill: transparent;
  stroke: currentColor;
  stroke-width: 0.95;
  vector-effect: non-scaling-stroke;
}

.rag-flow-diagram .rag-datastore-title {
  font-size: 16px;
  font-weight: 650;
}

.rag-flow-diagram .rag-datastore-detail {
  fill: var(--muted);
  font-size: 15.5px;
}

.rag-flow-diagram .rag-merge-note {
  fill: var(--muted);
  font-size: 14.5px;
  font-weight: 700;
  letter-spacing: 0.45px;
}

.rag-flow-diagram .rag-outcome-marker {
  fill: var(--paper);
  stroke: currentColor;
  stroke-width: 1.25;
  vector-effect: non-scaling-stroke;
}

.rag-flow-diagram .rag-answer-outcome .rag-outcome-marker {
  fill: currentColor;
}

.rag-flow-diagram .rag-outcome-title {
  font-size: 14.5px;
  font-weight: 560;
}

.rag-flow-diagram .rag-arrow,
.rag-flow-diagram .rag-branch,
.rag-flow-diagram .rag-junction-link {
  fill: none;
  stroke: currentColor;
  stroke-width: 0.95;
  vector-effect: non-scaling-stroke;
}

.rag-flow-diagram .rag-index-link {
  stroke-width: 0.85;
}

.rag-flow-diagram .rag-arrow,
.rag-flow-diagram .rag-junction-link {
  marker-end: url(#rag-flow-arrow);
}

.rag-flow-diagram .rag-merge-input,
.rag-flow-diagram .rag-terminal-link {
  marker-end: none;
}

.rag-flow-diagram .rag-branch {
  stroke-width: 0.8;
}

.rag-flow-diagram .rag-junction {
  fill: currentColor;
}

.rag-flow-diagram .rag-arrowhead {
  fill: var(--ink);
}

.table-scroll {
  position: relative;
  width: 100%;
  margin: 2rem 0;
  overflow-x: auto;
  border-block: 1px solid var(--ink);
  overscroll-behavior-inline: contain;
  scrollbar-width: thin;
}

.table-scroll:focus-visible,
.system-flow-diagram:focus-visible,
.validation-flow-diagram:focus-visible,
.fallback-flow-diagram:focus-visible,
.rag-flow-diagram:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 4px;
}

.table-scroll-hint {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

table {
  width: 100%;
  min-width: 38rem;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.78rem;
  font-variant-numeric: lining-nums tabular-nums;
  line-height: 1.42;
}

th,
td {
  padding: 0.75rem 0.7rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  background: rgba(23, 23, 22, 0.035);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

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

.chapter-navigation {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: clamp(4rem, 8vw, 7rem);
  padding-top: 1.25rem;
  border-top: 1px solid var(--ink);
  font-family: var(--sans);
}

.chapter-navigation a {
  font-size: 0.76rem;
  line-height: 1.35;
  text-decoration: none;
}

.chapter-navigation a:hover {
  text-decoration: underline;
  text-underline-offset: 0.2em;
}

.chapter-navigation span {
  display: block;
  margin-bottom: 0.35rem;
  color: var(--muted);
  font-size: 0.62rem;
  font-weight: 650;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.chapter-next {
  text-align: right;
}

.book-footer {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 2rem;
  border-top: 1px solid var(--ink);
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.68rem;
}

.book-footer p {
  margin: 0;
}

.mobile-bar {
  display: none;
}

.toc-dialog {
  width: min(28rem, calc(100vw - 1.5rem));
  max-height: calc(100dvh - 1.5rem);
  margin: auto 0.75rem auto auto;
  padding: 0;
  border: 1px solid var(--ink);
  background: var(--paper-raised);
  color: var(--ink);
  font-family: var(--sans);
}

.toc-dialog::backdrop {
  background: rgba(23, 23, 22, 0.42);
  backdrop-filter: blur(2px);
}

.dialog-header {
  position: sticky;
  z-index: 1;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem;
  border-bottom: 1px solid var(--line);
  background: var(--paper-raised);
}

.dialog-header h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: 1.5rem;
  font-weight: 500;
}

.dialog-close {
  padding: 0.35rem 0;
}

.toc-dialog nav {
  padding: 0.5rem 1rem 1.5rem;
}

.toc-dialog li {
  border-bottom: 1px solid var(--line);
}

.toc-dialog nav a {
  display: grid;
  grid-template-columns: 2.2rem minmax(0, 1fr) auto;
  gap: 0.35rem;
  padding: 0.75rem 0;
  font-size: 0.82rem;
  line-height: 1.35;
  text-decoration: none;
}

.toc-dialog .toc-title small {
  margin-top: 0.18rem;
  font-size: 0.55rem;
}

.dialog-footer {
  position: sticky;
  bottom: 0;
  padding: 0.75rem 1rem max(0.75rem, env(safe-area-inset-bottom));
  border-top: 1px solid var(--line);
  background: var(--paper-raised);
}

.dialog-footer .action-link {
  width: 100%;
}

.search-dialog {
  width: min(42rem, calc(100vw - 1.5rem));
  max-height: calc(100dvh - 1.5rem);
  margin: auto;
  padding: 0;
  overflow: hidden;
  border: 1px solid var(--ink);
  background: var(--paper-raised);
  color: var(--ink);
  font-family: var(--sans);
}

.search-dialog::backdrop {
  background: rgba(23, 23, 22, 0.42);
  backdrop-filter: blur(2px);
}

.search-toolbar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.search-toolbar .dialog-close {
  flex: 0 0 2.75rem;
  min-width: 2.75rem;
  padding: 0;
}

.search-panel {
  max-height: calc(100dvh - 1.5rem);
  padding: 1.25rem 1.25rem max(1.25rem, env(safe-area-inset-bottom));
  overflow-y: auto;
  overscroll-behavior: contain;
}

.search-field {
  position: relative;
  flex: 1;
  min-width: 0;
}

.search-field input {
  width: 100%;
  min-height: 3.25rem;
  padding: 0.75rem 3rem 0.75rem 0;
  border: 0;
  border-bottom: 1px solid var(--ink);
  border-radius: 0;
  outline: 0;
  background: transparent;
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.2rem, 1rem + 0.8vw, 1.55rem);
  -webkit-appearance: none;
  appearance: none;
}

.search-field input::placeholder {
  color: var(--muted);
  opacity: 1;
}

.search-field input:focus-visible {
  border-bottom-width: 2px;
}

.search-field kbd {
  position: absolute;
  top: 50%;
  right: 0;
  min-width: 1.75rem;
  padding: 0.12rem 0.35rem;
  transform: translateY(-50%);
  border: 1px solid var(--line-strong);
  background: var(--paper);
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.68rem;
  text-align: center;
}

.search-empty {
  margin: 0.75rem 0 0;
  color: var(--muted);
  font-size: 0.7rem;
  line-height: 1.45;
}

.search-results {
  margin: 1rem 0 0;
  padding: 0;
  border-top: 1px solid var(--ink);
  list-style: none;
}

.search-results:empty {
  display: none;
}

.search-results li {
  border-bottom: 1px solid var(--line);
}

.search-results a {
  display: grid;
  gap: 0.22rem;
  min-height: 2.75rem;
  padding: 0.9rem 0.25rem;
  text-decoration: none;
}

.search-results a:hover strong {
  text-decoration: underline;
  text-decoration-thickness: 0.06em;
  text-underline-offset: 0.18em;
}

.search-result-meta {
  color: var(--muted);
  font-size: 0.62rem;
  font-weight: 650;
  letter-spacing: 0.065em;
  text-transform: uppercase;
}

.search-results strong {
  font-family: var(--serif);
  font-size: 1.08rem;
  font-weight: 550;
  line-height: 1.25;
}

.search-result-excerpt {
  color: var(--muted);
  font-family: var(--serif);
  font-size: 0.82rem;
  line-height: 1.45;
}

.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

@media (max-width: 60rem) {
  html {
    scroll-padding-top: 4.5rem;
  }

  .book-shell {
    display: block;
  }

  .sidebar {
    display: none;
  }

  .mobile-bar {
    position: sticky;
    z-index: 80;
    top: 0;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    min-height: 3.5rem;
    padding: 0.35rem max(1rem, env(safe-area-inset-right)) 0.35rem max(1rem, env(safe-area-inset-left));
    border-bottom: 1px solid var(--line);
    background: color-mix(in srgb, var(--paper) 94%, transparent);
    backdrop-filter: blur(12px);
    font-family: var(--sans);
  }

  .mobile-title {
    max-width: 18rem;
    overflow: hidden;
    font-family: var(--serif);
    font-size: 0.92rem;
    line-height: 1.1;
    text-decoration: none;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .mobile-actions {
    display: flex;
    flex: none;
    gap: 0.65rem;
    align-items: center;
  }

  .source-map li {
    grid-template-columns: 1fr;
  }

  .menu-button {
    display: flex;
    gap: 0.45rem;
    align-items: center;
  }

  .menu-button span,
  .menu-button span::before,
  .menu-button span::after {
    display: block;
    width: 0.9rem;
    height: 1px;
    background: currentColor;
    content: "";
  }

  .menu-button span {
    position: relative;
  }

  .menu-button span::before {
    position: absolute;
    top: -0.25rem;
  }

  .menu-button span::after {
    position: absolute;
    top: 0.25rem;
  }
}

@media (max-width: 42rem) {
  :root {
    --page-gutter: clamp(1.125rem, 5.7vw, 2rem);
  }

  body {
    line-height: 1.64;
  }

  .cover {
    min-height: calc(100svh - 3.5rem);
  }

  .cover h1 {
    font-size: clamp(3rem, 16.5vw, 5rem);
  }

  .contents-page ol {
    grid-template-columns: 1fr;
  }

  .source-map li,
  .reference-list > li {
    grid-template-columns: 1fr;
  }

  .source-map-references {
    white-space: normal;
  }

  .index-columns {
    column-count: 1;
  }

  .chapter-header h2 {
    font-size: clamp(2.45rem, 13vw, 4.25rem);
  }

  .system-flow-diagram,
  .validation-flow-diagram,
  .fallback-flow-diagram,
  .rag-flow-diagram {
    overflow-x: auto;
    overscroll-behavior-inline: contain;
    scrollbar-width: thin;
  }

  .system-flow-diagram svg,
  .validation-flow-diagram svg,
  .fallback-flow-diagram svg,
  .rag-flow-diagram svg {
    min-width: 36rem;
  }

  .table-scroll-hint {
    position: sticky;
    left: 0;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    width: max-content;
    min-width: min(100%, calc(100vw - 2 * var(--page-gutter)));
    height: auto;
    padding: 0.55rem 0;
    margin: 0;
    overflow: visible;
    clip: auto;
    border: 0;
    color: var(--muted);
    font-family: var(--sans);
    font-size: 0.68rem;
    font-weight: 650;
    letter-spacing: 0.04em;
    line-height: 1.3;
    text-transform: uppercase;
    white-space: normal;
  }

  .table-scroll-hint span {
    font-size: 1rem;
    font-weight: 400;
  }

  .chapter-navigation {
    grid-template-columns: 1fr;
  }

  .key-value-example > div {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }

  .cache-key-composition > div {
    grid-template-columns: 1fr;
    gap: 0.18rem;
  }

  .latency-band {
    grid-template-columns: 1fr;
    gap: 0.18rem;
  }

  .golden-record > div,
  .cost-model dl > div {
    grid-template-columns: 1fr;
    gap: 0.18rem;
  }

  .cost-alternative {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }

  .chapter-next {
    padding-top: 1rem;
    border-top: 1px solid var(--line);
    text-align: left;
  }

  .book-footer {
    display: block;
  }

  .book-footer p + p {
    margin-top: 0.4rem;
  }

  .search-dialog {
    margin: auto 0.75rem 0.75rem;
  }
}

@media (max-width: 22rem) {
  .mobile-title {
    max-width: 7.5rem;
  }

  .mobile-actions {
    gap: 0.35rem;
  }

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

  .release-countdown > span:nth-child(3) {
    padding-left: 0;
    border-left: 0;
  }

  .release-countdown > span:nth-child(n + 3) {
    padding-top: 0.75rem;
    margin-top: 0.75rem;
    border-top: 1px solid var(--line);
  }

  .cover-actions {
    display: grid;
    grid-template-columns: 1fr;
  }

  .action-link {
    width: 100%;
  }

  .cover h1 {
    font-size: 2.8rem;
  }

  .chapter-header h2 {
    font-size: 2.35rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reading-progress span {
    transition: none;
  }
}

@media print {
  @page {
    size: A5;
    margin: 15mm 13mm 18mm;
  }

  :root {
    --paper: #fff;
    --paper-raised: #fff;
    --ink: #000;
    --muted: #333;
    --line: #bbb;
    --line-strong: #777;
  }

  html,
  body {
    background: #fff;
    font-size: 10pt;
    line-height: 1.5;
  }

  .mobile-bar,
  .sidebar,
  .reading-progress,
  .toc-dialog,
  .search-dialog,
  .chapter-navigation,
  .book-footer,
  .skip-link,
  .text-button,
  .site-only,
  .dialog-footer,
  .table-scroll-hint {
    display: none !important;
  }

  .book-shell {
    display: block;
  }

  .pdf-only {
    display: block;
  }

  .cover,
  .foreword,
  .contents-page,
  .chapter,
  .back-matter,
  .book-footer {
    width: auto;
    margin: 0;
    padding-inline: 0;
  }

  .cover {
    min-height: 165mm;
    break-after: page;
  }

  .cover h1 {
    font-size: 42pt;
  }

  .cover-date {
    position: absolute;
    bottom: 10mm;
    left: 0;
    margin: 0;
    font-size: 7.5pt;
  }

  .foreword,
  .contents-page {
    break-after: page;
  }

  .foreword {
    padding-block: 10mm 0;
  }

  .contents-page {
    min-height: auto;
    padding-block: 8mm 0;
  }

  .contents-page ol {
    gap: 0 8mm;
  }

  .contents-page h2 {
    margin-bottom: 4mm;
  }

  .contents-page a {
    padding: 2.4mm 0;
    font-size: 9.2pt;
  }

  .chapter {
    display: contents;
    padding-block: 0 8mm;
    border-top: 0;
    break-before: auto;
  }

  .chapter-header {
    margin-bottom: 0;
    padding-top: 10mm;
    border-top: 1px solid var(--line);
    break-before: page;
    break-after: page;
    break-inside: avoid-page;
  }

  .chapter-header h2 {
    margin-bottom: 6mm;
    font-size: 28pt;
  }

  .chapter-art {
    width: 104mm;
    max-width: 100%;
    height: auto;
    max-height: none;
    /*
     * Keep PDF image XObjects opaque. Chromium/Skia represents CSS filters,
     * clip paths, and masks with soft-mask transparency groups; Preview/PDFKit
     * can tile or displace those groups at some zoom levels. The source art is
     * already grayscale on white, so the print edition needs no live effects.
     */
    clip-path: none;
    filter: none;
    -webkit-mask-image: none !important;
    mask-image: none !important;
    print-color-adjust: exact;
  }

  #chapter-03-prefill-and-decode-are-different-jobs .chapter-art {
    width: 110mm;
  }

  #chapter-09-trace-the-whole-user-journey .chapter-art {
    width: 116mm;
  }

  .chapter-body p {
    margin: 0.9em 0;
    orphans: 3;
    widows: 3;
  }

  .chapter-body ul,
  .chapter-body ol {
    margin: 2.8mm 0;
  }

  .chapter-body ol {
    padding-inline-start: 1.75em;
  }

  .chapter-body li {
    margin: 0.28em 0;
  }

  .source-section + .source-section {
    margin-top: 9mm;
    padding-top: 7mm;
  }

  .source-section > h3 {
    margin-bottom: 4mm;
    font-size: 18pt;
  }

  .chapter-body h4 {
    margin: 7mm 0 2.5mm;
    font-size: 14pt;
  }

  .chapter-body h5,
  .chapter-body h6 {
    margin: 5mm 0 2mm;
    font-size: 9.5pt;
  }

  .source-section > h3,
  .chapter-body h4,
  .chapter-body h5,
  .chapter-body h6 {
    break-after: avoid-page;
    break-inside: avoid;
  }

  .chapter-body h3,
  .chapter-body h4,
  blockquote,
  .code-frame,
  .editorial-example,
  .system-flow-diagram,
  .fallback-flow-diagram,
  .rag-flow-diagram,
  .validation-flow-diagram,
  .table-scroll {
    break-inside: avoid;
  }

  .chapter-body li,
  .source-map li,
  .reference-list > li,
  .index-group li {
    break-inside: avoid;
  }

  .chapter-body ul > li:first-child,
  .chapter-body ol > li:first-child,
  table tbody tr:first-child {
    break-after: avoid-page;
  }

  .chapter-body p:has(+ ul),
  .chapter-body p:has(+ ol),
  .chapter-body p:has(+ .code-frame),
  .chapter-body p:has(+ .editorial-example),
  .chapter-body p:has(+ .fallback-flow-diagram),
  .chapter-body p:has(+ .rag-flow-diagram),
  .chapter-body p:has(+ .validation-flow-diagram),
  .chapter-body p:has(+ .table-scroll),
  .source-section > p:has(+ .section-sources),
  .source-section > p:has(+ p + .section-sources) {
    break-after: avoid-page;
  }

  #section-02-harness-engineering-not-just-prompt-engineering > p:first-of-type {
    break-after: auto;
    break-inside: avoid-page;
  }

  .chapter-body ul > li:nth-last-child(2),
  .chapter-body ol > li:nth-last-child(2),
  table tbody tr:nth-last-child(2) {
    break-after: avoid-page;
  }

  .checklist {
    break-inside: avoid-page;
  }

  .section-sources {
    gap: 1mm 1.5mm;
    margin-top: 4mm !important;
    padding-top: 2mm;
    font-size: 7.2pt;
    line-height: 1.3;
    break-inside: avoid;
  }

  .section-sources strong {
    font-size: 6.5pt;
  }

  .table-scroll {
    break-inside: auto;
    overflow: visible;
  }

  .table-scroll,
  .code-frame,
  .editorial-example,
  .system-flow-diagram,
  .fallback-flow-diagram,
  .rag-flow-diagram,
  .validation-flow-diagram {
    margin: 3mm 0;
  }

  .code-frame pre {
    padding: 0;
    font-size: 7.8pt;
    line-height: 1.55;
  }

  .key-value-example > div {
    grid-template-columns: 31mm minmax(0, 1fr);
    gap: 3mm;
    padding: 1.35mm 0;
  }

  .key-value-example dt,
  .key-value-example dd {
    font-size: 7.6pt;
    line-height: 1.35;
  }

  .cache-key-composition > div {
    grid-template-columns: 31mm minmax(0, 1fr);
    gap: 3mm;
    padding: 1.5mm 0;
  }

  .cache-key-composition dt {
    font-size: 7pt;
    line-height: 1.35;
  }

  .cache-key-composition dd {
    font-size: 7.6pt;
    line-height: 1.35;
  }

  .cache-key-term + .cache-key-term::before {
    margin-inline: 1.5mm;
  }

  .latency-budget .latency-total {
    padding: 1.5mm 0;
  }

  .latency-budget .latency-total strong {
    font-size: 9pt;
  }

  .latency-budget .latency-total span {
    font-size: 6.4pt;
  }

  .latency-band {
    grid-template-columns: 31mm minmax(0, 1fr);
    gap: 3mm;
    padding: 1.5mm 0;
  }

  .latency-band > p {
    font-size: 7pt;
    line-height: 1.35;
  }

  .latency-band > div {
    font-size: 7.6pt;
    line-height: 1.35;
  }

  .latency-stage + .latency-stage::before {
    margin-inline: 1.5mm;
  }

  .kv-total,
  .cost-total {
    padding: 1.5mm 0;
  }

  .kv-total strong,
  .cost-total strong {
    font-size: 9pt;
  }

  .kv-total span,
  .cost-total span {
    font-size: 6.4pt;
  }

  .kv-factors {
    gap: 1mm 0;
    padding: 1.7mm 0;
  }

  .kv-factor {
    gap: 1mm;
  }

  .kv-factor + .kv-factor::before {
    margin-inline: 1.8mm;
  }

  .kv-factor strong {
    font-size: 7.8pt;
  }

  .kv-factor small {
    font-size: 6.6pt;
  }

  .golden-record > div,
  .cost-model dl > div {
    grid-template-columns: 31mm minmax(0, 1fr);
    gap: 3mm;
    padding: 1.5mm 0;
  }

  .golden-record dt,
  .cost-model dt {
    font-size: 7pt;
    line-height: 1.35;
  }

  .golden-record dd,
  .cost-model dd {
    font-size: 7.5pt;
    line-height: 1.35;
  }

  .golden-record dd span + span::before,
  .cost-model dd > span + span::before {
    margin-inline: 1.5mm;
  }

  .trace-tree {
    padding: 1.7mm 0;
  }

  .trace-tree ul {
    padding-left: 3mm;
  }

  .trace-tree ul ul {
    margin-left: 1mm;
  }

  .trace-tree li {
    margin: 0.45mm 0;
    font-size: 7.3pt;
    line-height: 1.3;
  }

  .trace-tree ul ul > li {
    padding-left: 2.5mm;
  }

  .trace-tree ul ul > li::before {
    width: 1.8mm;
  }

  .trace-tree > ul > li > span {
    font-size: 9pt;
  }

  .cost-alternative {
    grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
    gap: 1.5mm;
  }

  .cost-model > p {
    padding: 1.5mm 0;
    font-size: 7pt;
    line-height: 1.35;
  }

  .system-flow-diagram svg {
    max-height: 127mm;
  }

  .validation-flow-diagram svg {
    max-height: 82mm;
  }

  .fallback-flow-diagram svg {
    max-height: 58mm;
  }

  .rag-flow-diagram svg {
    max-height: 61mm;
  }

  table {
    min-width: 0;
    table-layout: fixed;
    font-size: 7.2pt;
  }

  thead {
    display: table-header-group;
  }

  tr {
    break-inside: avoid-page;
  }

  th,
  td {
    padding: 1.5mm;
    overflow-wrap: break-word;
    word-break: normal;
    hyphens: auto;
  }

  #section-15-retrieval-and-answer-evals table {
    font-size: 6.9pt;
  }

  #section-15-retrieval-and-answer-evals th,
  #section-15-retrieval-and-answer-evals td {
    padding: 1.25mm;
  }

  #section-04-four-caches-that-must-not-be-confused {
    font-size: 9.2pt;
    line-height: 1.36;
  }

  #section-04-four-caches-that-must-not-be-confused > p {
    margin: 0.65em 0;
  }

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}