@import url('../../src/brand-system.css');

:root {
  color: #20201f;
  background: #f0eee6;
  font-family: 'Microsoft YaHei', 'PingFang SC', 'Noto Sans CJK SC', sans-serif;
  font-synthesis: none;
  --paper: #f0eee6;
  --paper-deep: #e5e0d5;
  --paper-light: #f7f4ed;
  --ink: #20201f;
  --muted: #6e6b66;
  --burgundy: #6b2431;
  --peach: #b9958c;
  --peach-on-dark: #b9958c;
  --navy: #243450;
  --navy-deep: #18263c;
  --sage: #dde7e1;
  --practice: #e5e1d8;
  --line: rgba(32, 32, 31, .18);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; background: var(--paper); color: var(--ink); }
a { color: inherit; text-decoration: none; }
button, summary { font: inherit; }
::selection { background: var(--burgundy); color: #fff; }

.term {
  color: var(--burgundy);
  font-family: Georgia, serif;
  font-style: italic;
  font-weight: 400;
}
.light-term { color: var(--peach-on-dark); }
.english {
  color: var(--navy);
  font-family: Georgia, serif;
  font-size: 1.06em;
  font-style: italic;
}
.english.on-dark { color: #fff; }

.topbar {
  height: 82px;
  padding: 0 clamp(24px, 5vw, 76px);
  border-bottom: 1px solid var(--line);
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  background: rgba(240, 238, 230, .96);
  font: 12px/1.4 Consolas, monospace;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.brand { display: inline-flex; align-items: center; gap: 13px; justify-self: start; }
.brand-mark { width: 36px; height: 36px; flex: 0 0 36px; object-fit: contain; display: block; }
.topbar .brand-name {
  color: var(--navy);
  font-family: Georgia, serif;
  font-size: 1.42rem;
  font-weight: 500;
  line-height: 1;
  letter-spacing: .005em;
  text-transform: none;
}
.lesson-index span { color: var(--burgundy); margin: 0 8px; }
.map-link { justify-self: end; border: 1px solid var(--ink); padding: 11px 17px; }
.map-link:hover { background: var(--navy); color: var(--paper); }

.hero {
  min-height: calc(100vh - 82px);
  padding: 68px clamp(24px, 6.4vw, 98px) 72px;
  display: grid;
  grid-template-columns: 1.08fr .92fr;
  gap: 5vw;
  align-items: center;
  overflow: hidden;
}
.eyebrow {
  margin: 0;
  color: var(--navy);
  font: 600 12px/1.5 Consolas, monospace;
  letter-spacing: .13em;
  text-transform: uppercase;
}
.hero h1,
.section-heading h2,
.worked-intro h2,
.closure-heading h2 { font-family: Georgia, 'Songti SC', STSong, SimSun, serif; }
.hero h1 { margin: 28px 0 32px; letter-spacing: -.05em; }
.hero h1 > .term { display: block; font-size: clamp(84px, 9.5vw, 144px); line-height: .76; }
.hero h1 > span {
  display: block;
  margin-top: 30px;
  color: var(--ink);
  font-size: clamp(37px, 4.2vw, 64px);
  font-weight: 600;
  line-height: 1.13;
}
.hero-question { max-width: 630px; margin: 0; padding-top: 23px; border-top: 1px solid var(--ink); font-family: 'Songti SC', STSong, SimSun, serif; }
.hero-question > span { display: block; color: var(--muted); font-size: 15px; }
.hero-question > strong { display: block; margin-top: 9px; color: var(--navy); font-size: clamp(22px, 2vw, 30px); font-weight: 500; line-height: 1.48; }
.hero-goal { max-width: 610px; margin: 20px 0 0; color: var(--muted); font-family: 'Songti SC', STSong, SimSun, serif; font-size: 16px; line-height: 1.76; }

.force-stage { min-height: 230px; display: grid; place-items: center; }
.ab-diagram {
  width: min(100%, 480px);
  display: grid;
  grid-template-columns: auto minmax(120px, 1fr) auto;
  align-items: center;
  gap: clamp(14px, 2.6vw, 28px);
}
.ab-node { position: static; display: flex; flex-direction: column; align-items: center; gap: 12px; transform: none; }
.ab-node span {
  width: clamp(76px, 7.5vw, 96px);
  height: clamp(76px, 7.5vw, 96px);
  display: grid;
  place-items: center;
  border-radius: 50%;
  font: 600 clamp(40px, 4.6vw, 56px)/1 Georgia, serif;
}
.ab-node small { color: inherit; font: 600 11px/1.4 'Songti SC', STSong, SimSun, serif; letter-spacing: .06em; white-space: nowrap; }
.ab-b { color: var(--burgundy); }
.ab-b span {
  position: relative;
  isolation: isolate;
  border: 0;
  border-radius: 0;
  background: transparent;
  padding-top: 8px;
  transform: translateY(6px);
}
.ab-b span::before,
.ab-b span::after {
  content: '';
  position: absolute;
  clip-path: polygon(50% 0, 100% 100%, 0 100%);
  pointer-events: none;
}
.ab-b span::before { inset: 0; z-index: -2; background: var(--burgundy); }
.ab-b span::after { inset: 3px 4px 4px; z-index: -1; background: var(--paper); }
.ab-a { color: var(--navy); }
.ab-a span { background: var(--navy); color: var(--paper); }
.ab-connector { position: static; display: flex; align-items: center; justify-content: center; gap: 11px; color: var(--burgundy); transform: none; }
.ab-connector i { flex: 1; min-width: 32px; border-top: 1px solid currentColor; opacity: .5; }
.ab-connector strong { font-size: clamp(24px, 2.5vw, 34px); }

.section { padding: 96px clamp(24px, 6.4vw, 98px); }
.split-section { display: grid; grid-template-columns: .72fr 1.28fr; gap: 7vw; }
.section-heading h2,
.worked-intro h2,
.closure-heading h2 {
  margin: 21px 0 0;
  color: var(--ink);
  font-size: clamp(44px, 4.8vw, 72px);
  font-weight: 600;
  line-height: 1.05;
  letter-spacing: -.042em;
}
.section-content { min-width: 0; font-family: 'Songti SC', STSong, SimSun, serif; font-size: 17px; line-height: 1.68; }
.section-content p { margin: 0 0 1.1em; }
.section-content ul,
.section-content ol { line-height: 1.62; }
.lead-in { color: var(--muted); font-size: 16px; }
.workbench { border-top: 1px solid var(--ink); padding-top: 14px; }
.sentence-display {
  margin: 0;
  padding: 36px 0 38px;
  color: var(--navy);
  border-bottom: 1px solid var(--line);
  font: 600 clamp(31px, 3.4vw, 53px)/1.2 Georgia, serif;
  letter-spacing: -.02em;
}
.compact-sentence { padding: 27px 0; font-size: clamp(27px, 2.7vw, 41px); }

.prompt-block {
  margin: 28px 0 23px;
  padding: 27px 30px;
  background: var(--paper-deep);
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  column-gap: 25px;
}
.prompt-block > *:not(.prompt-label) { grid-column: 2; }
.prompt-block p { margin-top: 0; }
.prompt-label {
  grid-column: 1;
  grid-row: 1 / span 5;
  color: var(--burgundy);
  font: 600 18px/1.45 'Songti SC', STSong, SimSun, serif;
  letter-spacing: .015em;
}
.text-quote {
  margin: 20px 0;
  padding: 12px 0 12px 20px;
  border-left: 3px solid var(--burgundy);
  color: var(--navy);
  font: 500 18px/1.65 'Songti SC', STSong, SimSun, serif;
}

.disclosure { margin: 18px 0 0; border-top: 1px solid var(--ink); border-bottom: 1px solid var(--line); }
.disclosure summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 18px 0;
  color: var(--burgundy);
  cursor: pointer;
  list-style: none;
  font: 600 17px/1.45 'Songti SC', STSong, SimSun, serif;
  letter-spacing: .01em;
}
.disclosure summary::-webkit-details-marker { display: none; }
.disclosure summary::after { content: '+'; color: var(--burgundy); font: 400 26px/1 Georgia, serif; }
.disclosure[open] summary::after { content: '−'; }
.disclosure-body {
  margin: 4px 0 28px;
  padding: 27px 30px 29px;
  background: var(--paper-light);
  border-left: 3px solid var(--burgundy);
  box-shadow: none;
}
.disclosure-body > :first-child { margin-top: 0; }
.disclosure-body > :last-child { margin-bottom: 0; }
.disclosure-body > p { margin: 0; line-height: 1.64; }
.disclosure-body > p + p { margin-top: 13px; padding-top: 13px; border-top: 1px solid var(--line); }
.disclosure-body .text-quote { margin: 14px 0; padding: 0; border-left: 0; color: var(--navy); font-size: 17px; line-height: 1.62; }

.dark-section { background: var(--navy); color: var(--paper); }
.section-heading.light h2 { color: var(--paper); }
.section-heading.light .eyebrow { color: var(--peach-on-dark); }
.dark-content { color: rgba(255, 255, 255, .84); }
.dark-content .lead-in { color: rgba(255, 255, 255, .6); }
.dark-sentence { color: #fff; border-bottom-color: rgba(255, 255, 255, .2); }
.dark-prompt { background: rgba(255, 255, 255, .075); }
.dark-prompt .prompt-label { color: var(--peach-on-dark); }
.text-quote.on-dark { color: #fff; border-color: var(--peach-on-dark); }
.dark-disclosure { border-top-color: rgba(255, 255, 255, .55); border-bottom-color: rgba(255, 255, 255, .18); }
.dark-disclosure summary,
.dark-disclosure summary::after { color: var(--peach-on-dark); }
.dark-disclosure .disclosure-body { background: rgba(255, 255, 255, .07); border-left-color: var(--peach-on-dark); box-shadow: none; }
.dark-disclosure .disclosure-body > p + p { border-top-color: rgba(255,255,255,.15); }
.dark-disclosure .disclosure-body .text-quote { color: #fff; }
.model-comparison { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin: 30px 0; }
.model-panel { min-height: 0; padding: 25px 27px; border: 1px solid rgba(255, 255, 255, .2); }
.model-label { display: block; margin-bottom: 17px; font: 600 16px/1.4 'Songti SC', STSong, SimSun, serif; }
.rejected-model { color: rgba(255, 255, 255, .76); }
.rejected-model .model-label { color: rgba(255, 255, 255, .62); }
.corrected-model { border-color: rgba(185, 149, 140, .72); background: rgba(255, 255, 255, .045); }
.corrected-model .model-label { color: var(--peach-on-dark); }
.model-flow { display: grid; gap: 10px; font-size: 17px; line-height: 1.52; }
.model-flow i { color: var(--peach-on-dark); font-style: normal; }
.major-insight {
  margin: 32px 0 0;
  padding: 22px 24px;
  border: 1px solid rgba(192, 207, 203, .4);
  background: rgba(192, 207, 203, .12);
  color: #fff;
  font: 500 18px/1.7 'Microsoft YaHei', 'PingFang SC', 'Noto Sans CJK SC', sans-serif;
  letter-spacing: 0;
}
.paper-insight {
  margin-top: 19px;
  padding: 22px 24px;
  background: rgba(221, 217, 194, .48);
  border: 1px solid var(--line);
  color: var(--navy);
  box-shadow: none;
  font: 500 18px/1.7 'Microsoft YaHei', 'PingFang SC', 'Noto Sans CJK SC', sans-serif;
  letter-spacing: 0;
}

.model-upgrade { display: grid; grid-template-columns: .85fr 1.15fr; gap: 18px; margin-top: 32px; }
.upgrade-card { min-height: 0; padding: 27px 29px; display: flex; flex-direction: column; justify-content: flex-start; border: 1px solid var(--line); }
.upgrade-card > span { color: var(--burgundy); font: 600 17px/1.4 'Songti SC', STSong, SimSun, serif; }
.upgrade-card p { margin: 15px 0 0; color: var(--navy); font-size: 21px; line-height: 1.52; }
.shallow-card { background: var(--paper-light); }
.complete-card { background: var(--paper); border-left: 1px solid var(--line); border-top: 2px solid var(--burgundy); }

.model-section { background: var(--paper-light); }
.model-workbench { border-top: 1px solid var(--ink); padding-top: 22px; }
.model-workbench h3 { margin: 42px 0 15px; color: var(--navy); font: 600 28px/1.27 Georgia, 'Songti SC', STSong, SimSun, serif; }
.ab-definition { margin: 25px 0 36px; border-top: 1px solid var(--line); }
.ab-definition > div { display: grid; grid-template-columns: 82px 1fr; border-bottom: 1px solid var(--line); }
.ab-definition dt { padding: 21px 0; color: var(--burgundy); font: 600 40px/1 Georgia, serif; }
.ab-definition dd { margin: 0; padding: 21px 0; }
.definition-field {
  margin: 23px 0;
  padding: 27px 31px;
  background: var(--paper);
  border-left: 7px solid var(--burgundy);
  color: var(--navy);
  box-shadow: 0 7px 22px rgba(32, 32, 31, .04);
  font: 500 clamp(22px, 2.35vw, 32px)/1.46 Georgia, 'Songti SC', STSong, SimSun, serif;
}
.research-annotation.definition-field {
  padding: 22px 24px;
  background: rgba(221, 217, 194, .48);
  border: 1px solid var(--line);
  box-shadow: none;
  font: 500 18px/1.7 'Microsoft YaHei', 'PingFang SC', 'Noto Sans CJK SC', sans-serif;
}
.small-definition {
  padding: 13px 0 13px 20px;
  background: transparent;
  border-left-width: 4px;
  box-shadow: none;
  font: 500 18px/1.65 'Songti SC', STSong, SimSun, serif;
}
.intuition-field { margin: 44px 0; padding: clamp(31px, 4vw, 48px); background: var(--sage); position: relative; overflow: hidden; }
.field-label { position: relative; z-index: 1; color: var(--burgundy); font: 600 15px/1.4 'Songti SC', STSong, SimSun, serif; }
.intuition-field p { position: relative; z-index: 1; margin-top: 19px; color: var(--muted); }
.intuition-field .research-annotation { position: relative; z-index: 1; margin: 17px 0 0; padding: 22px 24px; border: 1px solid rgba(36, 52, 80, .16); background: rgba(221, 217, 194, .48); color: var(--navy); font: 500 18px/1.7 'Microsoft YaHei', 'PingFang SC', 'Noto Sans CJK SC', sans-serif; letter-spacing: 0; }
.three-step-model { display: grid; grid-template-columns: 1fr auto 1fr auto 1.3fr; align-items: stretch; margin: 23px 0 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.three-step-model span { display: grid; place-items: center; min-height: 122px; padding: 19px; text-align: center; }
.three-step-model i { display: grid; place-items: center; color: var(--burgundy); font-style: normal; }
.final-compression { margin-top: 44px; padding: 34px 36px; background: var(--navy); color: #fff; }
.final-compression span { display: block; margin-bottom: 15px; color: var(--peach-on-dark); font: 600 15px/1.4 'Songti SC', STSong, SimSun, serif; }
.final-compression strong { font: 600 clamp(26px, 3vw, 42px)/1.36 Georgia, 'Songti SC', STSong, SimSun, serif; }

.worked-section {
  padding: 98px clamp(24px, 8.5vw, 136px);
  background: var(--sage);
  display: grid;
  grid-template-columns: .9fr 1.1fr;
  gap: 6vw;
  position: relative;
  overflow: hidden;
}
.worked-section::after { content: '“'; position: absolute; right: 0; top: -115px; color: rgba(32, 32, 31, .065); font: 400 390px Georgia, serif; }
.worked-intro,
.worked-content { position: relative; z-index: 1; min-width: 0; }
.worked-intro h2 { color: var(--ink); line-height: 1.01; }
.worked-sentence { margin-top: 38px; color: var(--navy); border-bottom-color: rgba(32, 32, 31, .2); }
.worked-content { padding-top: 17px; font-family: 'Songti SC', STSong, SimSun, serif; font-size: 17px; line-height: 1.68; }
.worked-content > .prompt-label { display: block; margin-bottom: 15px; font-size: 18px; }
.worked-questions { margin: 0 0 32px; padding: 0; list-style: none; counter-reset: worked; border-top: 1px solid rgba(32, 32, 31, .32); }
.worked-questions li { counter-increment: worked; position: relative; display: block; padding: 17px 0 17px 54px; border-bottom: 1px solid rgba(32, 32, 31, .18); min-width: 0; line-height: 1.62; }
.worked-questions li::before { content: '0' counter(worked); position: absolute; left: 0; top: 21px; color: var(--burgundy); font: 600 11px Consolas, monospace; }
.worked-disclosure { border-top-color: var(--ink); }
.worked-disclosure .disclosure-body { background: rgba(248, 245, 238, .82); }

.branches-section { position: relative; background: var(--paper); }
.branches-section .section-heading { position: relative; padding-left: 0; border-left: 0; }
.branches-section .section-heading::before { display: none; }
.branch-list { border-top: 1px solid var(--ink); }
.branch-row { display: grid; grid-template-columns: 60px 1fr; gap: 24px; padding: 37px 0; border-bottom: 1px solid var(--line); }
.branch-number { color: var(--burgundy); font: 600 12px Consolas, monospace; padding-top: 8px; }
.branch-row h3 { margin: 0 0 15px; color: var(--navy); font: 600 clamp(25px, 2.7vw, 37px)/1.27 Georgia, 'Songti SC', STSong, SimSun, serif; }
.branch-row h3::before {
  content: '!';
  width: 25px;
  height: 25px;
  margin-right: 12px;
  display: inline-grid;
  place-items: center;
  vertical-align: .12em;
  border: 1.5px solid var(--burgundy);
  border-radius: 50%;
  color: var(--burgundy);
  font: 600 15px/1 Georgia, serif;
}
.branch-row p { margin-bottom: .9em; }
.branch-row:first-child ul { margin: 20px 0 22px; padding: 0; list-style: none; }
.branch-row:first-child li { position: relative; padding: 9px 0 9px 25px; border-bottom: 1px solid var(--line); }
.branch-row:first-child li::before {
  content: '—';
  position: absolute;
  left: 0;
  top: 9px;
  color: var(--burgundy);
  font: 500 17px/1.4 'Songti SC', STSong, SimSun, serif;
}
.branches-section .text-quote,
.branches-section .small-definition {
  margin: 10px 0 22px;
  padding: 0;
  background: transparent;
  border: 0;
  box-shadow: none;
  color: var(--navy);
  font: 500 17px/1.7 'Songti SC', STSong, SimSun, serif;
}
.boundary-note { margin-top: 32px; padding: 25px 0 0; background: transparent; border-left: 0; border-top: 1px solid var(--line); }
.boundary-note ul { margin: 17px 0 0; }

.knowledge-practice-divider {
  position: relative;
  overflow: hidden;
  padding-top: 62px;
  background: linear-gradient(to bottom, var(--paper) 0%, #ebe7de 52%, var(--practice) 100%);
}
.knowledge-practice-divider img {
  display: block;
  width: 100%;
  height: auto;
  opacity: .76;
  mix-blend-mode: multiply;
  -webkit-mask-image: none;
  mask-image: none;
}

.practice-section { background: var(--practice); }
.practice-head { display: block; max-width: 760px; margin-bottom: 52px; }
.exercise-list { border-top: 1px solid var(--ink); }
.exercise-row { display: grid; grid-template-columns: 1.12fr .88fr; column-gap: 64px; padding: 44px 0; border-bottom: 1px solid var(--line); font-family: 'Songti SC', STSong, SimSun, serif; }
.exercise-title > span { color: var(--burgundy); font: 600 12px Consolas, monospace; }
.exercise-title h3 { margin: 14px 0 0; color: var(--navy); font: 600 clamp(26px, 2.7vw, 37px)/1.28 Georgia, 'Songti SC', STSong, SimSun, serif; }
.practice-sentence { padding: 25px 0 8px; font-size: clamp(26px, 2.65vw, 38px); border-bottom: 0; }
.exercise-prompt { align-self: center; color: var(--ink); font-size: 17px; line-height: 1.7; }
.exercise-disclosure { grid-column: 1 / -1; margin-top: 23px; }
.exercise-disclosure .disclosure-body { background: rgba(248, 245, 238, .82); }

.closure-section {
  padding: 102px clamp(24px, 6.4vw, 98px);
  background: var(--navy-deep);
  color: rgba(255, 255, 255, .84);
  display: grid;
  grid-template-columns: .72fr 1.28fr;
  gap: 7vw;
}
.closure-heading h2 { color: #fff; }
.closure-heading .eyebrow { color: var(--peach-on-dark); }
.closure-content { font-family: 'Songti SC', STSong, SimSun, serif; font-size: 17px; line-height: 1.68; }
.closure-sentence { padding-top: 29px; }
.answer-no { color: #fff; font: 600 clamp(34px, 4vw, 56px)/1.14 Georgia, 'Songti SC', STSong, SimSun, serif; }
.closure-series { margin: 42px 0 46px; border-top: 1px solid rgba(255, 255, 255, .24); }
.closure-item {
  display: grid;
  grid-template-columns: minmax(145px, .34fr) minmax(0, 1.66fr);
  gap: clamp(24px, 4vw, 58px);
  align-items: start;
  padding: 30px 0;
  border-bottom: 1px solid rgba(255, 255, 255, .18);
}
.closure-item > span { padding-top: 5px; color: var(--peach-on-dark); font: 600 15px/1.45 'Songti SC', STSong, SimSun, serif; letter-spacing: .01em; }
.closure-item > p { margin: 0; color: #fff; font: 500 clamp(24px, 2.7vw, 37px)/1.43 Georgia, 'Songti SC', STSong, SimSun, serif; letter-spacing: -.018em; }
.closure-item .term { color: var(--peach-on-dark); }
.completion-list { margin: 27px 0 0; padding: 0; list-style: none; border-top: 1px solid rgba(255, 255, 255, .22); }
.completion-list li { display: grid; grid-template-columns: 54px 1fr; gap: 18px; padding: 15px 0; border-bottom: 1px solid rgba(255, 255, 255, .14); }
.completion-list span { color: var(--peach-on-dark); font: 600 10px Consolas, monospace; padding-top: 6px; }
.closing-line { margin-top: 44px; color: #fff; font: 500 clamp(25px, 2.8vw, 37px)/1.4 Georgia, 'Songti SC', STSong, SimSun, serif; }

.page-footer { padding: 48px clamp(24px, 6.4vw, 98px); background: var(--navy); color: var(--paper); display: flex; justify-content: space-between; align-items: center; }
.footer-link { padding-bottom: 8px; border-bottom: 1px solid rgba(255, 255, 255, .58); font: 600 12px Consolas, monospace; letter-spacing: .05em; }
.back-top { width: 60px; height: 60px; display: grid; place-items: center; border: 1px solid rgba(255, 255, 255, .42); border-radius: 50%; font-size: 25px; }
summary:focus-visible,
a:focus-visible { outline: 2px solid var(--burgundy); outline-offset: 5px; }
.dark-section summary:focus-visible,
.closure-section a:focus-visible,
.page-footer a:focus-visible { outline-color: var(--peach-on-dark); }

@media (max-width: 900px) {
  .topbar { grid-template-columns: 1fr auto; }
  .lesson-index { display: none; }
  .hero { grid-template-columns: 1fr; min-height: auto; padding-top: 56px; }
  .force-stage { min-height: 210px; }
  .split-section,
  .worked-section,
  .closure-section { grid-template-columns: 1fr; gap: 54px; }
  .model-comparison,
  .model-upgrade { grid-template-columns: 1fr; }
  .three-step-model { grid-template-columns: 1fr; }
  .three-step-model i { transform: rotate(90deg); min-height: 28px; }
  .three-step-model span { min-height: auto; padding: 26px; }
  .exercise-row { grid-template-columns: 1fr; gap: 26px; }
  .exercise-disclosure { grid-column: 1; }
}

@media (max-width: 620px) {
  .topbar { height: 70px; padding: 0 16px; }
  .brand-mark { width: 32px; height: 32px; flex-basis: 32px; }
  .topbar .brand-name { font-size: .98rem; }
  .map-link { border: 0; padding: 8px 0; font-size: 11px; }
  .hero { padding: 46px 18px 52px; }
  .hero h1 > .term { font-size: clamp(70px, 23vw, 100px); }
  .hero h1 > span { margin-top: 24px; font-size: clamp(33px, 10vw, 47px); line-height: 1.2; }
  .ab-diagram { grid-template-columns: auto minmax(70px, 1fr) auto; gap: 8px; }
  .ab-node span { width: 64px; height: 64px; font-size: 36px; }
  .ab-b span { padding-top: 6px; transform: translateY(4px); }
  .ab-node small { font-size: 9px; }
  .ab-connector i { min-width: 14px; }
  .section,
  .worked-section,
  .closure-section { padding: 76px 18px; }
  .section-heading h2,
  .worked-intro h2,
  .closure-heading h2 { font-size: 41px; line-height: 1.16; }
  .section-content,
  .worked-content,
  .closure-content { font-size: 16px; }
  .sentence-display { padding: 33px 0; font-size: 29px; line-height: 1.3; }
  .prompt-block { grid-template-columns: 1fr; padding: 25px 21px; }
  .prompt-block > *:not(.prompt-label),
  .prompt-label { grid-column: 1; grid-row: auto; }
  .prompt-label { margin-bottom: 16px; }
  .disclosure-body { padding: 24px 21px 26px; }
  .model-panel { min-height: auto; }
  .major-insight { font-size: 16px; }
  .upgrade-card { padding: 24px; }
  .definition-field { padding: 26px 22px; font-size: 27px; }
  .small-definition { padding: 12px 0 12px 18px; font-size: 16px; }
  .intuition-field { padding: 30px 22px; }
  .intuition-field .research-annotation { font-size: 16px; }
  .final-compression { padding: 30px 22px; }
  .final-compression strong { font-size: 31px; }
  .worked-section::after { font-size: 290px; top: -70px; }
  .branch-row { grid-template-columns: 38px 1fr; gap: 10px; padding: 34px 0; }
  .branch-row h3 { font-size: 27px; }
  .branch-row h3::before { width: 22px; height: 22px; margin-right: 8px; font-size: 13px; }
  .boundary-note { padding-left: 0; }
  .knowledge-practice-divider { padding-top: 42px; }
  .exercise-row { padding: 40px 0; }
  .exercise-title h3 { font-size: 27px; }
  .practice-sentence { font-size: 27px; }
  .closure-item { grid-template-columns: 1fr; gap: 13px; padding: 25px 0; }
  .closure-item > span { padding-top: 0; }
  .closure-item > p { font-size: 27px; line-height: 1.46; }
  .page-footer { padding: 40px 18px; }
  .back-top { width: 50px; height: 50px; }
}

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