@charset "UTF-8";
@font-face {
  font-family: "Handbook Sans";
  src: url("fonts/reading-sans.woff2") format("woff2");
  font-style: normal;
  font-weight: 400 700;
  font-display: swap
}

@font-face {
  font-family: "Handbook Serif";
  src: url("fonts/reading-serif.woff2") format("woff2");
  font-style: normal;
  font-weight: 400 700;
  font-display: swap
}

:root {
  --paper: #f7f7f5;
  --ink: #0b0c0e;
  --muted: #63666b;
  --accent: #245fcc;
  --surface: var(--paper);
  --text: var(--ink);
  --secondary: var(--muted);
  --highlight: var(--accent);
  --divider: #d7d9dd;
  --sans: "Handbook Sans","Noto Sans SC","Microsoft YaHei",sans-serif;
  --serif: "Handbook Serif","Noto Serif SC",serif;
  --gutter: 48px;
  --nav: 72px
}

* {
  box-sizing: border-box
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav) + 28px)
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 18px/1.85 var(--sans);
  -webkit-font-smoothing: antialiased;
  overflow-x: clip
}

body:has(dialog[open]) {
  overflow: hidden
}

h1,h2,h3,h4,p {
  margin: 0
}

h1,h2,h3,h4 {
  line-height: 1.4;
  font-weight: 600
}

em {
  font-style: normal
}

a {
  color: inherit;
  text-decoration: none
}

button,textarea {
  font: inherit;
  color: inherit;
  border-radius: 0
}

button {
  cursor: pointer;
  border: 0;
  background: none
}

button:disabled {
  cursor: default
}

button,a,summary {
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent
}

a:focus-visible,button:focus-visible,textarea:focus-visible,summary:focus-visible {
  outline: 2px solid var(--highlight);
  outline-offset: 5px
}

[hidden] {
  display: none!important
}

::selection {
  background: #c5d8ff;
  color: #0b0c0e
}

.page-width {
  max-width: 1240px;
  width: calc(100% - var(--gutter)*2);
  margin-inline: auto
}

.paper {
  background: var(--paper);
  color: var(--ink)
}

.soft {
  --surface: #eeeff1;
  background: var(--surface);
  color: var(--ink)
}

.dark {
  --surface: #0b0c0e;
  --text: #f7f7f5;
  --secondary: #b4b6be;
  --highlight: #9fbdff;
  --divider: #34363a;
  background: var(--surface);
  color: var(--text)
}

.eyebrow,.small-label {
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--secondary)
}

.text-link {
  text-decoration: underline;
  text-underline-offset: 5px;
  color: var(--highlight)
}

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

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 20px;
  padding: 10px 20px;
  background: var(--ink);
  color: var(--paper);
  transform: translateY(-170%)
}

.skip-link:focus {
  transform: none
}

/* Persistent document navigation. */
.masthead {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--paper);
  border-bottom: 1px solid var(--divider)
}

.masthead>.page-width {
  display: flex;
  align-items: center;
  gap: 26px;
  min-height: var(--nav)
}

.wordmark {
  font-size: 16px;
  white-space: nowrap;
  font-weight: 600
}

.rail-links {
  display: flex;
  gap: 24px;
  margin-left: auto
}

.rail-links>a {
  display: flex;
  align-items: center;
  gap: 7px;
  min-height: var(--nav);
  border-bottom: 2px solid transparent;
  font-size: 12px;
  white-space: nowrap;
  transition: color 180ms,border-color 180ms
}

.rail-links .toc-number {
  font-size: 11px;
  color: var(--secondary)
}

.rail-links .toc-title {
  font: inherit
}

.rail-links .toc-page,.rail-links small {
  display: none
}

.rail-links>a[aria-current="location"] {
  color: var(--accent);
  border-color: var(--accent)
}

.motion-toggle {
  min-height: 44px;
  padding-inline: 0;
  font-size: 11px;
  white-space: nowrap;
  color: var(--muted)
}

.header-menu {
  display: none;
  margin-left: auto;
  min-height: 44px;
  font-size: 13px;
  padding-inline: 0
}

.reading-progress {
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left
}

/* Opening scene: readable first, then a scroll-linked typographic exit. */
.cover {
  position: relative
}

.cover-stage {
  min-height: calc(100svh - var(--nav));
  padding: 76px 0 100px;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden
}

.cover-content {
  text-align: center
}

.cover h1 {
  font-size: clamp(52px,7.8vw,108px);
  line-height: 1.2;
  letter-spacing: -.055em;
  margin-top: 32px;
  transform-origin: center
}

.cover h1 em {
  color: #a8aab2
}

.cover-intro {
  max-width: 46em;
  margin: 34px auto 0;
  font-size: 18px;
  line-height: 1.9;
  color: var(--secondary)
}

.cover-actions {
  display: flex;
  justify-content: center;
  gap: 30px;
  flex-wrap: wrap;
  margin-top: 36px
}

.start-link {
  display: inline-flex;
  gap: 40px;
  align-items: center;
  min-height: 52px;
  padding: 10px 24px;
  background: var(--paper);
  color: var(--ink);
  font-size: 14px
}

.secondary-link {
  background: none;
  color: var(--text);
  border: 1px solid var(--divider)
}

.start-link span {
  font-size: 19px;
  transition: transform 200ms
}

.start-link:hover span {
  transform: translateY(3px)
}

.cover-scope {
  margin-top: 26px;
  font-size: 12px;
  color: var(--secondary)
}

.cover-baseline {
  position: absolute;
  bottom: 23px;
  left: var(--gutter);
  right: var(--gutter);
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: var(--secondary);
  letter-spacing: .08em
}

.story-enabled .cover {
  height: 170svh
}

.story-enabled .cover-stage {
  position: sticky;
  top: var(--nav);
  height: calc(100svh - var(--nav));
  min-height: 0;
  padding-block: 32px 64px
}

.story-enabled .cover h1 {
  font-size: min(7.8vw,11svh,108px)
}

.cover:focus-within #cover-title,.cover:focus-within .eyebrow,.cover:focus-within .cover-intro,.cover:focus-within .cover-scope {
  transform: none!important;
  opacity: 1!important
}

/* Three real video slots share a single exhibition area. */
.showcase {
  padding-block: 74px 42px;
  position: relative;
  z-index: 2;
  border-bottom: 1px solid var(--divider)
}

.showcase-heading {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 30px;
  margin-bottom: 38px
}

.showcase-heading h2 {
  font-size: clamp(30px,3.8vw,48px);
  letter-spacing: -.03em;
  margin-top: 8px
}

.showcase-heading>p {
  font-size: 13px;
  color: var(--secondary)
}

.showcase-grid {
  display: grid;
  grid-template-columns: repeat(3,minmax(0,1fr));
  gap: 22px
}

.video-slot {
  min-width: 0
}

.insert-meta {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 12px;
  color: var(--secondary);
  font-size: 12px
}

.insert-meta h3 {
  font: inherit
}

.video-frame {
  display: grid;
  place-items: center;
  aspect-ratio: 4/3;
  min-height: 150px;
  border: 1px solid #c9ccd1;
  background: var(--paper);
  overflow: hidden
}

.video-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 9px;
  padding: 24px
}

.video-word {
  font-size: 18px;
  letter-spacing: .03em
}

.video-state {
  font-size: 12px;
  color: var(--secondary)
}

.video-caption {
  font-size: 13px;
  margin-top: 12px;
  color: var(--secondary)
}

.video-caption:empty {
  display: none
}

.video-frame video,.video-frame iframe {
  width: 100%;
  height: 100%;
  border: 0;
  object-fit: contain;
  background: var(--ink)
}

.embed-load {
  display: grid;
  place-content: center;
  gap: 16px;
  text-align: center;
  width: 100%;
  height: 100%;
  padding: 20px
}

.embed-load small {
  font-size: 13px
}

.video-source-link {
  text-decoration: underline;
  text-underline-offset: 4px
}

.video-error {
  display: none;
  font-size: 13px;
  padding-top: 12px
}

.video-error.is-visible {
  display: block
}

.showcase-switcher {
  display: none
}

.showcase-footer {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  border-top: 1px solid var(--divider);
  padding-top: 22px;
  margin-top: 30px;
  font-size: 12px;
  color: var(--secondary)
}

.showcase-footer a {
  min-height: 44px;
  color: var(--accent)
}

/* A document abstract and a single, complete contents list. */
.contents {
  padding-block: 100px 116px
}

.contents-layout {
  display: grid;
  grid-template-columns: .9fr 1.1fr;
  gap: 100px
}

.contents-intro h2 {
  font-size: clamp(30px,3.8vw,48px);
  letter-spacing: -.035em;
  margin-block: 14px 28px
}

.contents-intro>p:not(.eyebrow) {
  font-size: 17px;
  max-width: 29em;
  margin-bottom: 18px
}

.contents-intro>.text-link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-size: 14px;
  margin-top: 10px
}

.contents-list {
  border-top: 1px solid var(--ink)
}

.contents-list>a {
  display: grid;
  grid-template-columns: 36px 1fr 22px;
  gap: 20px;
  align-items: start;
  padding-block: 20px;
  border-bottom: 1px solid var(--divider)
}

.toc-number {
  font: 20px/1.6 var(--serif);
  color: var(--secondary)
}

.toc-title {
  font-size: 22px;
  font-weight: 500
}

.toc-title small {
  display: block;
  font-size: 14px;
  font-weight: 400;
  color: var(--secondary);
  margin-top: 4px
}

.toc-page {
  font-size: 20px
}

.contents-list>a:hover .toc-title {
  color: var(--accent)
}

/* Each chapter has a strong title, a readable introduction and distinct content. */
.chapter {
  padding-block: 84px 48px;
  border-top: 1px solid var(--divider)
}

.chapter-running {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  color: var(--secondary);
  font-size: 12px;
  padding-bottom: 52px;
  font-variant-numeric: tabular-nums
}

.chapter-heading {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 90px;
  align-items: end;
  margin-bottom: 66px
}

.chapter-heading h2 {
  font-size: clamp(36px,4.4vw,60px);
  line-height: 1.35;
  letter-spacing: -.04em
}

.chapter-heading em {
  color: var(--secondary)
}

.chapter-deck {
  font-size: 18px;
  line-height: 1.95;
  max-width: 31em;
  padding-bottom: 5px
}

.chapter-footer {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--divider);
  font-size: 13px;
  color: var(--secondary)
}

.chapter-footer>a {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  gap: 26px
}

.chapter-footer>a:last-child {
  color: var(--highlight)
}

.article-split {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 70px;
  margin-top: 62px;
  padding-top: 32px;
  border-top: 1px solid var(--divider)
}

.article-split h3 {
  font-size: 23px
}

.article-split p {
  max-width: 44em;
  font-size: 17px
}

.article-split p+p {
  margin-top: 18px
}

.check-words {
  border-block: 1px solid var(--divider);
  padding-block: 18px;
  overflow-wrap: anywhere;
  color: var(--secondary)
}

.practice {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 30px;
  border-top: 2px solid var(--highlight);
  margin-top: 44px;
  padding-top: 24px
}

.practice>span {
  font-size: 14px;
  color: var(--highlight);
  font-weight: 500
}

.practice p,.action-steps {
  font-size: 17px;
  max-width: 45em;
  line-height: 1.9
}

.practice p+p {
  margin-top: 14px
}

.action-steps {
  margin: 0;
  padding-left: 1.3em
}

.action-steps>li+li {
  margin-top: 8px
}

.action-steps>li::marker {
  color: var(--highlight)
}

.chapter-more {
  margin-top: 48px;
  border-top: 1px solid var(--divider);
  padding-top: 28px
}

.chapter-more>h3 {
  font-size: 19px;
  margin-bottom: 12px
}

.chapter-more>p {
  font-size: 16px;
  color: var(--secondary);
  max-width: 47em;
  margin-bottom: 16px
}

.editorial-details {
  border-bottom: 1px solid var(--divider)
}

.editorial-details summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  min-height: 70px;
  padding-block: 18px;
  cursor: pointer;
  list-style: none;
  font-size: 16px
}

.editorial-details summary::-webkit-details-marker {
  display: none
}

.editorial-details summary>span {
  font-size: 24px;
  font-weight: 400;
  color: var(--secondary);
  flex-shrink: 0;
  transition: transform 200ms
}

.editorial-details[open] summary>span {
  transform: rotate(45deg)
}

.editorial-details>div {
  max-width: 960px;
  padding-block: 8px 30px;
  font-size: 17px
}

.editorial-details>div>p+p {
  margin-top: 16px
}

/* 01: three problem definitions, no fabricated image comparisons. */
.problem-spread {
  display: grid;
  grid-template-columns: repeat(3,minmax(0,1fr));
  gap: 50px
}

.problem-spread>article {
  padding-top: 26px;
  border-top: 2px solid var(--text)
}

.problem-number {
  font: 52px/1.2 var(--serif);
  color: var(--secondary);
  display: block;
  margin-bottom: 26px
}

.problem-spread h3 {
  font-size: 27px;
  margin-bottom: 15px
}

.problem-spread p {
  font-size: 17px;
  color: var(--secondary)
}

.problem-direction {
  border-top: 1px solid var(--divider);
  margin-top: 26px;
  padding-top: 18px
}

.problem-direction>span {
  font-size: 12px;
  color: var(--highlight)
}

.problem-direction>p {
  color: var(--text);
  margin-top: 8px
}

/* 02: direct before/after text, with a real selection control. */
.reframe-demo {
  display: grid;
  grid-template-columns: 280px minmax(0,1fr);
  gap: 64px
}

.reframe-demo:not(.is-interactive) {
  display: block
}

.reframe-demo:not(.is-interactive) .reframe-choices {
  display: none
}

.reframe-choices>.small-label {
  margin-bottom: 18px
}

.reframe-buttons button {
  width: 100%;
  display: grid;
  grid-template-columns: 24px 1fr 20px;
  gap: 14px;
  align-items: center;
  text-align: left;
  padding: 20px 0;
  border-bottom: 1px solid var(--divider);
  min-height: 66px;
  font-size: 16px;
  transition: color 180ms
}

.reframe-buttons button:first-child {
  border-top: 1px solid var(--divider)
}

.reframe-buttons button>span:first-child {
  font-size: 12px;
  color: var(--secondary)
}

.reframe-buttons button[aria-pressed="true"] {
  color: var(--highlight)
}

.reframe-buttons button>span:last-child {
  transition: transform 180ms
}

.reframe-buttons button:hover>span:last-child {
  transform: translateX(4px)
}

.reframe-stage {
  padding: 28px 0 28px 60px;
  border-left: 1px solid var(--divider);
  min-height: 350px
}

.reframe-example+.reframe-example {
  margin-top: 50px
}

.is-interactive .reframe-example {
  margin-top: 0
}

.from-label,.to-label {
  font-size: 12px;
  color: var(--secondary)
}

.reframe-from {
  font-size: 23px;
  margin-top: 10px;
  color: var(--secondary)
}

.reframe-arrow {
  display: block;
  font: 32px/1.5 var(--serif);
  margin-block: 18px;
  color: var(--highlight)
}

.reframe-example h3 {
  font-size: clamp(26px,3vw,40px);
  line-height: 1.6;
  margin-top: 10px;
  letter-spacing: -.03em
}

/* 03: scroll-linked layers represent the actual prompt structure. */
.assembly-stage {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
  min-height: 540px;
  padding-block: 30px 60px
}

.assembly-copy h3 {
  font-size: clamp(30px,3.6vw,48px);
  letter-spacing: -.035em;
  margin-block: 16px 26px
}

.assembly-copy>p:not(.eyebrow) {
  max-width: 28em;
  font-size: 17px
}

.assembly-visual {
  display: flex;
  flex-direction: column;
  gap: 18px;
  perspective: 1200px;
  min-width: 0
}

.assembly-layer {
  border: 1px solid #bfc4cd;
  padding: 20px 28px;
  background: var(--paper);
  display: grid;
  grid-template-columns: 95px 1fr;
  gap: 5px 18px;
  min-height: 126px;
  transform-origin: center;
  backface-visibility: hidden
}

.assembly-layer>span {
  font-size: 12px;
  grid-row: 1/3;
  color: var(--secondary);
  padding-top: 7px
}

.assembly-layer>strong {
  font-size: 24px;
  font-weight: 600
}

.assembly-layer>p {
  font-size: 14px;
  color: var(--secondary)
}

.assembly-layer:nth-child(2) {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink)
}

.assembly-layer:nth-child(2)>span,.assembly-layer:nth-child(2)>p {
  color: #b4b6be
}

.scene-hint {
  display: none!important
}

.story-enabled .scene-hint {
  display: block!important;
  margin-top: 28px;
  font-size: 12px!important;
  color: var(--secondary)
}

.story-enabled .assembly-scene {
  height: 150svh
}

.story-enabled .assembly-stage {
  position: sticky;
  top: var(--nav);
  height: calc(100svh - var(--nav));
  min-height: 0;
  padding-block: 50px
}

.story-enabled .assembly-visual {
  display: block;
  position: relative;
  height: 500px
}

.story-enabled .assembly-layer {
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 126px;
  margin-top: -63px
}

.composer {
  margin-top: 35px;
  background: var(--paper);
  padding: 36px;
  border: 1px solid var(--divider)
}

.composer-heading {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 30px;
  margin-bottom: 30px
}

.composer-heading h3 {
  font-size: 27px;
  letter-spacing: -.025em;
  margin-top: 10px
}

.composer-heading>p {
  font-size: 14px;
  color: var(--secondary)
}

.compose-toolbar {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  padding-block: 14px 20px;
  font-size: 13px;
  position: relative
}

.compose-toolbar>p {
  color: var(--accent)
}

.compose-meter {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--divider)
}

.compose-meter>span {
  display: block;
  height: 100%;
  background: var(--accent);
  transform: scaleX(.666667);
  transform-origin: left;
  transition: transform 260ms ease
}

.prompt-builder {
  display: grid;
  grid-template-columns: 1fr 1.3fr 1fr
}

.compose-column {
  padding: 26px;
  min-width: 0
}

.compose-column:first-child {
  padding-left: 0
}

.compose-column:last-child {
  padding-right: 0
}

.compose-column+.compose-column {
  border-left: 1px solid var(--divider)
}

.compose-label>span {
  font-size: 12px;
  color: var(--secondary)
}

.compose-label h4 {
  font-size: 21px;
  letter-spacing: -.02em;
  margin-block: 9px 20px
}

.compose-column>p {
  font-size: 16px
}

.subject-column label {
  display: block;
  font-size: 13px;
  color: var(--accent);
  margin-bottom: 10px
}

.subject-column textarea {
  width: 100%;
  min-height: 165px;
  display: block;
  border: 1px solid var(--accent);
  background: #fff;
  padding: 12px;
  font-size: 16px;
  line-height: 1.8;
  resize: vertical
}

.subject-column textarea::placeholder {
  color: var(--muted);
  opacity: 1
}

.subject-column .field-note {
  font-size: 12px;
  color: var(--secondary);
  margin-top: 12px
}

.compose-action {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  border-top: 1px solid var(--divider);
  padding-top: 26px;
  margin-top: 6px
}

.compose-action>p {
  font-size: 14px;
  color: var(--secondary)
}

.copy-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  min-height: 44px;
  padding: 9px 16px;
  border: 1px solid var(--divider);
  font-size: 13px;
  white-space: nowrap;
  flex-shrink: 0;
  transition: color 180ms,border-color 180ms,background-color 180ms
}

.copy-button:hover,.copy-button.is-copied {
  border-color: var(--highlight);
  color: var(--highlight)
}

.primary-copy {
  min-height: 52px;
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
  padding-inline: 24px;
  font-size: 14px
}

.primary-copy:hover,.primary-copy.is-copied {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--paper)
}

.assembled-preview {
  border-top: 1px solid var(--divider);
  margin-top: 24px
}

.prompt-text {
  font-size: 17px;
  line-height: 1.95;
  white-space: pre-line;
  overflow-wrap: anywhere;
  max-width: 45em
}

#composed-subject {
  color: var(--accent)
}

.prompt-footnote {
  font-size: 13px;
  color: var(--secondary);
  margin-top: 18px;
  line-height: 1.8
}

.term-note {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 30px;
  padding-top: 28px
}

.term-note h3 {
  font-size: 14px;
  font-weight: 400;
  color: var(--secondary)
}

.term-note p {
  font-size: 15px;
  color: var(--secondary);
  max-width: 50em
}

.prompt-sheet {
  margin-top: 28px;
  padding: 28px 32px;
  border: 1px solid var(--divider)
}

.prompt-sheet-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 22px
}

.prompt-sheet-head h3,.prompt-sheet-head h4 {
  font-size: 17px;
  font-weight: 500
}

.editorial-details .prompt-sheet {
  margin-top: 0;
  margin-bottom: 24px
}

/* 04: source pairs retain a direct row-by-row relationship. */
.reference-intro {
  max-width: 800px;
  margin-bottom: 40px;
  font-size: 18px
}

.reference-intro strong {
  font-weight: 600
}

.reference-spread {
  border-top: 1px solid var(--text)
}

.reference-spread>div {
  display: grid;
  grid-template-columns: 1fr 90px 1fr;
  gap: 36px;
  align-items: center;
  padding-block: 28px;
  border-bottom: 1px solid var(--divider)
}

.reference-spread>div>p {
  font-size: clamp(20px,2.4vw,30px);
  line-height: 1.6;
  letter-spacing: -.025em
}

.reference-spread>div>p:last-child {
  color: var(--secondary)
}

.reference-spread>div>span {
  font-size: 13px;
  color: var(--secondary)
}

.reference-spread .reference-head {
  padding-block: 16px
}

.table-note {
  font-size: 13px;
  color: var(--secondary);
  margin-top: 18px
}

.ratio-values {
  font-size: 21px;
  margin-block: 20px
}

.ratio-values>span {
  padding-inline: 16px
}

/* 05: content and texture define the two sides of an editing instruction. */
.reset-spread {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px
}

.reset-spread>div {
  padding-top: 30px;
  border-top: 1px solid var(--text)
}

.reset-word {
  font-size: 54px;
  line-height: 1.2;
  font-weight: 600;
  letter-spacing: -.04em;
  color: var(--secondary)
}

.reset-spread>div:last-child .reset-word {
  color: var(--accent)
}

.reset-spread h3 {
  font-size: 24px;
  margin-block: 20px
}

.reset-spread p {
  font-size: 17px;
  padding-block: 13px;
  border-bottom: 1px solid var(--divider)
}

/* 06: a progress line shows the image handoff, never a fabricated image. */
.workflow-stage {
  padding-block: 10px 20px
}

.workflow-caption {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 34px
}

.workflow-caption .scene-hint {
  margin: 0
}

.workflow-steps {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 88px;
  list-style: none;
  margin: 0;
  padding: 0
}

.workflow-steps>li {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: 24px;
  align-content: start;
  border-top: 1px solid var(--divider);
  padding-top: 28px
}

.workflow-number {
  font: 64px/1.2 var(--serif);
  color: var(--secondary)
}

.workflow-steps h3 {
  font-size: 30px;
  margin-block: 10px 18px;
  letter-spacing: -.025em
}

.workflow-steps p {
  font-size: 17px;
  color: var(--secondary);
  max-width: 23em
}

.workflow-steps .text-link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-size: 13px;
  margin-top: 12px
}

.transfer-line {
  display: grid;
  grid-template-columns: 100px 1fr 100px;
  gap: 25px;
  align-items: center;
  margin-top: 46px;
  font-size: 13px
}

.transfer-end {
  text-align: right
}

.transfer-track {
  position: relative;
  height: 1px;
  background: var(--divider)
}

.transfer-track::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--highlight);
  transform: scaleX(var(--flow-progress,1));
  transform-origin: left
}

.transfer-track>i {
  position: absolute;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--highlight);
  top: -3px;
  left: var(--flow-percent,100%);
  transform: translateX(-4px)
}

.transfer-line>p {
  grid-column: 2;
  text-align: center;
  color: var(--highlight);
  font-size: 13px
}

.handoff-note {
  margin-top: 34px;
  border-left: 2px solid var(--highlight);
  padding-left: 22px
}

.handoff-note strong {
  font-size: 18px;
  font-weight: 500
}

.handoff-note p {
  font-size: 15px;
  color: var(--secondary);
  margin-top: 8px;
  max-width: 46em
}

.story-enabled .workflow-scene {
  height: 145svh
}

.story-enabled .workflow-stage {
  position: sticky;
  top: var(--nav);
  min-height: calc(100svh - var(--nav));
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-block: 48px
}

.closing {
  padding-block: 100px
}

.closing .page-width {
  display: grid;
  grid-template-columns: 1.25fr 1fr;
  gap: 0 80px
}

.closing .eyebrow {
  grid-column: 1/-1;
  margin-bottom: 28px
}

.closing h2 {
  font-size: clamp(38px,4.8vw,66px);
  line-height: 1.35;
  letter-spacing: -.04em
}

.closing h2 em {
  color: var(--secondary)
}

.closing nav {
  align-self: end;
  border-top: 1px solid var(--ink)
}

.closing nav>a {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  padding-block: 23px;
  border-bottom: 1px solid var(--divider);
  font-size: 18px
}

.site-footer {
  border-top: 1px solid var(--divider);
  padding-block: 34px 46px
}

.site-footer>.page-width {
  display: flex;
  justify-content: space-between;
  gap: 60px;
  align-items: start
}

.site-footer p {
  max-width: 40em;
  font-size: 12px;
  color: var(--secondary);
  margin-top: 14px
}

.source-link {
  font-size: 12px;
  color: var(--secondary);
  white-space: nowrap;
  min-height: 44px;
  display: inline-flex;
  align-items: center
}

/* Native dialog and compact mobile reading navigation. */
.reading-bar {
  display: none
}

.toc-dialog {
  width: min(600px,calc(100% - 32px));
  max-height: calc(100svh - 48px);
  overflow: auto;
  border: 0;
  padding: 30px 36px;
  background: var(--paper);
  color: var(--ink)
}

.toc-dialog::backdrop {
  background: rgb(0 0 0 / .6)
}

.dialog-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 22px
}

.dialog-header h2 {
  font-size: 24px
}

.dialog-close {
  min-height: 44px;
  font-size: 14px
}

.dialog-links>a {
  display: grid;
  grid-template-columns: 30px 1fr 20px;
  gap: 16px;
  align-items: start;
  padding-block: 16px;
  border-top: 1px solid var(--divider)
}

.dialog-links .toc-title {
  font-size: 19px
}

.dialog-links .toc-title small {
  font-size: 12px
}

.dialog-cover {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  margin-top: 20px;
  font-size: 14px
}

.dialog-links>a[aria-current="location"] {
  color: var(--accent)
}

.motion-off {
  scroll-behavior: auto
}

.motion-off *,.motion-off *::before,.motion-off *::after {
  animation: none!important;
  transition: none!important
}

@media(max-width:1100px) {
  :root {
    --gutter: 34px
  }
  .rail-links {
    gap: 14px
  }
  .rail-links>a {
    font-size: 11px
  }
  .masthead>.page-width {
    gap: 18px
  }
  .chapter-heading {
    gap: 50px
  }
  .chapter-deck {
    font-size: 17px
  }
  .contents-layout {
    gap: 60px
  }
  .assembly-stage {
    gap: 40px
  }
  .assembly-layer {
    padding-inline: 22px;
    grid-template-columns: 80px 1fr
  }
  .workflow-steps {
    gap: 50px
  }
  .workflow-steps>li {
    grid-template-columns: 60px 1fr;
    gap: 18px
  }
  .workflow-number {
    font-size: 52px
  }
}

@media(max-width:1000px) {
  :root {
    --nav: 64px
  }
  .rail-links {
    display: none
  }
  .header-menu {
    display: block
  }
  .chapter-heading {
    grid-template-columns: 1fr;
    gap: 24px;
    max-width: 820px
  }
  .chapter-deck {
    max-width: 42em
  }
  .contents-layout {
    grid-template-columns: 1fr;
    gap: 36px
  }
  .contents-intro>p:not(.eyebrow) {
    max-width: 45em
  }
  .contents-list {
    display: grid;
    grid-template-columns: 1fr 1fr;
    column-gap: 36px
  }
  .contents-list>a {
    grid-template-columns: 28px 1fr 20px;
    gap: 14px
  }
  .toc-title {
    font-size: 20px
  }
  .toc-title small {
    font-size: 13px
  }
  .reading-bar {
    display: block;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 35;
    background: var(--paper);
    border-top: 1px solid var(--divider);
    padding-bottom: env(safe-area-inset-bottom,0px)
  }
  .reading-bar>.reading-progress {
    top: -2px;
    bottom: auto
  }
  .reading-position {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 5px 16px 0;
    color: var(--secondary);
    font-size: 11px
  }
  .reading-position button {
    margin-left: auto;
    font-size: 12px;
    min-height: 36px
  }
  .mobile-part-links {
    display: grid;
    grid-template-columns: repeat(6,minmax(0,1fr));
    gap: 2px;
    padding: 0 10px 8px
  }
  .mobile-part-links>a {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    border-top: 2px solid transparent;
    padding-top: 5px
  }
  .mobile-part-links .toc-number {
    font: 12px var(--sans);
    color: inherit
  }
  .mobile-part-links .toc-title {
    font-size: 10px;
    font-weight: 400;
    white-space: nowrap
  }
  .mobile-part-links .toc-page,.mobile-part-links small {
    display: none
  }
  .mobile-part-links a[aria-current="location"] {
    color: var(--accent);
    border-color: var(--accent)
  }
  .site-footer {
    padding-bottom: 140px
  }
  .composer-heading {
    display: block
  }
  .composer-heading>p {
    margin-top: 16px
  }
  .composer-heading>p br {
    display: none
  }
  .assembly-layer {
    display: block
  }
  .assembly-layer>span {
    display: block;
    padding: 0;
    margin-bottom: 6px
  }
  .assembly-layer>strong {
    font-size: 22px
  }
}

@media(max-width:760px) {
  :root {
    --gutter: 24px
  }
  body {
    font-size: 17px
  }
  .masthead>.page-width {
    gap: 14px
  }
  .wordmark {
    font-size: 14px
  }
  .motion-toggle {
    font-size: 10px
  }
  .cover-stage {
    padding-block: 65px 88px;
    min-height: calc(92svh - var(--nav))
  }
  .cover h1 {
    font-size: clamp(37px,9.3vw,65px);
    letter-spacing: -.04em;
    margin-top: 26px
  }
  .cover-intro {
    font-size: 16px;
    text-align: left;
    margin-top: 28px;
    max-width: 30em
  }
  .cover-intro br {
    display: none
  }
  .cover-actions {
    gap: 12px;
    margin-top: 28px
  }
  .start-link {
    font-size: 13px;
    gap: 22px;
    padding-inline: 18px
  }
  .cover-scope {
    font-size: 10px;
    margin-top: 22px
  }
  .cover-baseline {
    font-size: 10px;
    bottom: 22px
  }
  .showcase {
    padding-block: 44px 26px
  }
  .showcase-heading {
    margin-bottom: 26px;
    display: block
  }
  .showcase-heading h2 {
    font-size: 31px
  }
  .showcase-heading>p {
    display: none
  }
  .showcase-grid {
    grid-template-columns: 1fr
  }
  .showcase.is-interactive .showcase-switcher {
    display: grid;
    grid-template-columns: repeat(3,1fr);
    margin-bottom: 20px;
    border-bottom: 1px solid var(--divider)
  }
  .showcase-switcher button {
    min-height: 48px;
    padding: 10px 4px;
    font-size: 12px;
    border-bottom: 2px solid transparent
  }
  .showcase-switcher button[aria-pressed="true"] {
    border-color: var(--accent);
    color: var(--accent)
  }
  .showcase-footer {
    margin-top: 24px;
    font-size: 11px
  }
  .video-frame {
    min-height: 160px
  }
  .contents {
    padding-block: 56px
  }
  .contents-intro h2 {
    font-size: 34px;
    margin-block: 12px 22px
  }
  .contents-intro>p:not(.eyebrow) {
    font-size: 16px
  }
  .contents-list {
    grid-template-columns: 1fr
  }
  .contents-list>a {
    padding-block: 18px
  }
  .toc-title {
    font-size: 21px
  }
  .toc-title small {
    font-size: 13px
  }
  .chapter {
    padding-block: 44px 28px
  }
  .chapter-running {
    font-size: 11px;
    padding-bottom: 32px
  }
  .chapter-heading {
    margin-bottom: 40px;
    gap: 22px
  }
  .chapter-heading h2 {
    font-size: clamp(30px,7.5vw,46px);
    line-height: 1.45;
    letter-spacing: -.035em
  }
  .chapter-deck {
    font-size: 17px;
    line-height: 1.85
  }
  .chapter-footer {
    margin-top: 36px;
    font-size: 12px;
    padding-top: 18px
  }
  .chapter-footer>a {
    gap: 14px
  }
  .problem-spread {
    grid-template-columns: 1fr;
    gap: 32px
  }
  .problem-spread>article {
    display: grid;
    grid-template-columns: 56px 1fr;
    gap: 12px 20px;
    padding-top: 22px
  }
  .problem-number {
    font-size: 34px;
    grid-row: 1/4;
    margin: 0
  }
  .problem-spread h3 {
    font-size: 24px;
    margin: 0
  }
  .problem-spread>article>p {
    grid-column: 2;
    font-size: 16px
  }
  .problem-direction {
    grid-column: 2;
    margin-top: 2px;
    padding-top: 15px
  }
  .problem-direction>p {
    font-size: 16px
  }
  .article-split {
    grid-template-columns: 1fr;
    gap: 20px;
    margin-top: 38px;
    padding-top: 26px
  }
  .article-split h3 {
    font-size: 22px
  }
  .article-split p {
    font-size: 16px
  }
  .practice {
    grid-template-columns: 1fr;
    gap: 12px;
    margin-top: 32px;
    padding-top: 22px
  }
  .practice p,.action-steps {
    font-size: 16px
  }
  .practice>span {
    font-size: 13px
  }
  .chapter-more {
    padding-top: 24px;
    margin-top: 36px
  }
  .chapter-more>h3 {
    font-size: 18px
  }
  .chapter-more>p {
    font-size: 15px
  }
  .editorial-details summary {
    font-size: 15px;
    min-height: 64px;
    gap: 16px
  }
  .editorial-details>div {
    font-size: 16px;
    padding-bottom: 24px
  }
  .reframe-demo {
    grid-template-columns: 1fr;
    gap: 28px
  }
  .reframe-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0 20px
  }
  .reframe-buttons button {
    font-size: 14px;
    grid-template-columns: 18px 1fr;
    gap: 8px;
    padding-block: 18px
  }
  .reframe-buttons button:nth-child(2) {
    border-top: 1px solid var(--divider)
  }
  .reframe-buttons button>span:last-child {
    display: none
  }
  .reframe-stage {
    padding: 25px 0 0;
    border-left: 0;
    border-top: 1px solid var(--divider);
    min-height: 330px
  }
  .reframe-from {
    font-size: 21px
  }
  .reframe-example h3 {
    font-size: 28px
  }
  .reframe-arrow {
    margin-block: 14px
  }
  .assembly-stage {
    grid-template-columns: 1fr;
    gap: 30px;
    padding: 0 0 36px;
    min-height: 0
  }
  .assembly-copy h3 {
    font-size: 33px;
    margin-block: 12px 20px
  }
  .assembly-copy>p:not(.eyebrow) {
    font-size: 16px;
    max-width: none
  }
  .assembly-visual {
    gap: 12px
  }
  .assembly-layer {
    display: grid;
    grid-template-columns: 78px 1fr;
    min-height: 0;
    padding: 18px;
    gap: 5px 12px
  }
  .assembly-layer>span {
    font-size: 11px;
    grid-row: 1/3;
    margin: 0;
    padding-top: 5px
  }
  .assembly-layer>strong {
    font-size: 22px
  }
  .assembly-layer>p {
    font-size: 13px
  }
  .composer {
    padding: 22px 18px;
    margin-top: 0
  }
  .composer-heading h3 {
    font-size: 25px
  }
  .composer-heading>p {
    font-size: 14px
  }
  .compose-toolbar {
    display: block;
    font-size: 12px;
    padding-block: 6px 17px
  }
  .compose-toolbar>p {
    margin-top: 6px
  }
  .prompt-builder {
    grid-template-columns: 1fr
  }
  .compose-column,.compose-column:first-child,.compose-column:last-child {
    padding: 22px 0
  }
  .compose-column+.compose-column {
    border-left: 0;
    border-top: 1px solid var(--divider)
  }
  .compose-label h4 {
    font-size: 22px;
    margin-bottom: 14px
  }
  .compose-column>p {
    font-size: 16px
  }
  .subject-column textarea {
    min-height: 150px
  }
  .compose-action {
    display: block;
    padding-top: 22px
  }
  .compose-action>p {
    font-size: 13px
  }
  .primary-copy {
    width: 100%;
    margin-top: 18px
  }
  .assembled-preview summary {
    font-size: 14px
  }
  .prompt-text {
    font-size: 16px;
    line-height: 1.95
  }
  .prompt-footnote {
    font-size: 12px
  }
  .term-note {
    grid-template-columns: 1fr;
    gap: 8px;
    padding-top: 23px
  }
  .term-note p {
    font-size: 14px
  }
  .prompt-sheet {
    padding: 20px 18px
  }
  .prompt-sheet-head {
    align-items: start;
    gap: 16px;
    flex-wrap: wrap;
    margin-bottom: 20px
  }
  .prompt-sheet-head h3,.prompt-sheet-head h4 {
    font-size: 16px
  }
  .copy-button {
    font-size: 12px;
    gap: 18px
  }
  .reference-intro {
    font-size: 16px;
    margin-bottom: 26px
  }
  .reference-spread>div {
    grid-template-columns: 1fr 42px 1fr;
    gap: 12px;
    padding-block: 22px
  }
  .reference-spread>div>p {
    font-size: 18px;
    line-height: 1.8
  }
  .reference-spread>div>span {
    font-size: 11px
  }
  .table-note {
    font-size: 12px
  }
  .ratio-values {
    font-size: 17px
  }
  .ratio-values>span {
    padding-inline: 6px
  }
  .reset-spread {
    grid-template-columns: 1fr;
    gap: 36px
  }
  .reset-spread>div {
    padding-top: 24px
  }
  .reset-word {
    font-size: 40px
  }
  .reset-spread h3 {
    font-size: 23px;
    margin-block: 16px
  }
  .reset-spread p {
    font-size: 16px
  }
  .workflow-stage {
    padding: 0
  }
  .workflow-caption {
    margin-bottom: 25px
  }
  .workflow-steps {
    grid-template-columns: 1fr;
    gap: 36px
  }
  .workflow-steps>li {
    grid-template-columns: 54px 1fr;
    gap: 20px;
    padding-top: 24px
  }
  .workflow-number {
    font-size: 43px
  }
  .workflow-steps h3 {
    font-size: 27px;
    margin-block: 8px 14px
  }
  .workflow-steps p {
    font-size: 16px
  }
  .transfer-line {
    grid-template-columns: 72px 1fr 78px;
    gap: 12px;
    font-size: 11px;
    margin-top: 32px
  }
  .transfer-line>p {
    font-size: 12px;
    grid-column: 1/-1
  }
  .handoff-note {
    margin-top: 26px;
    padding-left: 17px
  }
  .handoff-note strong {
    font-size: 17px
  }
  .handoff-note p {
    font-size: 14px
  }
  .closing {
    padding-block: 58px
  }
  .closing .page-width {
    grid-template-columns: 1fr;
    gap: 0
  }
  .closing h2 {
    font-size: 37px
  }
  .closing nav {
    margin-top: 36px
  }
  .closing nav>a {
    font-size: 16px;
    padding-block: 20px
  }
  .site-footer>.page-width {
    display: block
  }
  .site-footer p {
    font-size: 12px
  }
  .source-link {
    margin-top: 12px;
    font-size: 11px;
    white-space: normal
  }
  .toc-dialog {
    padding: 24px
  }
  .dialog-header h2 {
    font-size: 22px
  }
}

@media(max-width:380px) {
  :root {
    --gutter: 18px
  }
  .masthead>.page-width {
    gap: 12px
  }
  .wordmark {
    font-size: 13px
  }
  .chapter-heading h2 {
    font-size: 28px
  }
  .cover h1 {
    font-size: 34px
  }
  .cover-scope {
    font-size: 10px;
    letter-spacing: -.02em
  }
  .start-link {
    gap: 14px;
    padding-inline: 15px
  }
  .reframe-example h3 {
    font-size: 25px
  }
  .problem-spread>article {
    grid-template-columns: 44px 1fr;
    gap: 12px 16px
  }
  .reference-spread>div {
    gap: 9px;
    grid-template-columns: 1fr 36px 1fr
  }
  .reference-spread>div>p {
    font-size: 16px
  }
  .compose-label h4 {
    font-size: 21px
  }
  .assembly-layer {
    grid-template-columns: 68px 1fr;
    padding: 16px
  }
  .assembly-layer>strong {
    font-size: 20px
  }
}

@media(prefers-reduced-motion:reduce) {
  html {
    scroll-behavior: auto
  }
  *,*::before,*::after {
    animation: none!important;
    transition: none!important
  }
}

@media print {
  :root,.dark,.soft {
    --surface: #ffffff;
    --text: #0b0c0e;
    --secondary: #63666b;
    --highlight: #245fcc;
    --divider: #d7d9dd
  }
  body {
    font-size: 11pt;
    background: #fff
  }
  .page-width {
    width: 100%;
    max-width: none
  }
  .masthead,.reading-bar,.toc-dialog,.skip-link,.cover-actions,.cover-baseline,.copy-button,.scene-hint,.story-enabled .scene-hint,.showcase-switcher,.reframe-choices {
    display: none!important
  }
  .story-enabled .cover,.story-enabled .assembly-scene,.story-enabled .workflow-scene {
    height: auto
  }
  .story-enabled .cover-stage,.story-enabled .assembly-stage,.story-enabled .workflow-stage {
    position: static;
    height: auto;
    min-height: 0;
    padding-block: 24px
  }
  #cover-title,.cover-intro,.cover-actions,.cover-scope,.cover .eyebrow {
    transform: none!important;
    opacity: 1!important
  }
  .cover h1,.story-enabled .cover h1 {
    font-size: 40pt
  }
  .cover h1 em {
    color: var(--secondary)
  }
  .cover-stage {
    min-height: 0;
    padding: 28px 0
  }
  .contents,.chapter,.closing {
    padding-block: 28px
  }
  .chapter {
    break-before: page
  }
  .chapter-heading {
    display: block
  }
  .chapter-heading h2 {
    font-size: 30pt
  }
  .chapter-deck {
    margin-top: 20px
  }
  .chapter-running {
    padding-bottom: 24px
  }
  .story-enabled .assembly-visual {
    height: auto;
    display: flex
  }
  .story-enabled .assembly-layer {
    position: static;
    height: auto;
    margin: 0;
    transform: none!important
  }
  .assembly-stage {
    display: block
  }
  .assembly-visual {
    margin-top: 24px
  }
  .assembly-layer:nth-child(2) {
    background: #fff;
    color: #0b0c0e
  }
  .assembly-layer:nth-child(2)>span,.assembly-layer:nth-child(2)>p {
    color: #63666b
  }
  .reframe-demo {
    display: block
  }
  .reframe-stage {
    border: 0;
    padding: 0
  }
  .reframe-example[hidden] {
    display: block!important
  }
  .reframe-example+.reframe-example {
    margin-top: 30px
  }
  .reframe-example h3 {
    font-size: 20pt
  }
  .editorial-details>div {
    display: block!important
  }
  .showcase .video-slot[hidden] {
    display: block!important
  }
  .showcase-grid {
    grid-template-columns: repeat(3,1fr)
  }
  .workflow-steps>li {
    transform: none!important
  }
  .transfer-track {
    --flow-progress: 1!important;
    --flow-percent: 100%!important
  }
  .site-footer {
    padding-bottom: 24px
  }
  .chapter-footer {
    display: none
  }
}