:root {
  color-scheme: light;
  --paper: #ffffff;
  --page: #f4f6f7;
  --ink: #14263a;
  --body: #263c50;
  --muted: #526475;
  --rule: #cad4dd;
  --blue: #1459a6;
  --blue-light: #e7f0f9;
  --red: #ad3b35;
  --red-light: #fff0ed;
  --amber: #79520b;
  --amber-light: #fbf3df;
  --measure: 1180px;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.72;
  color: var(--body);
  background: var(--page);
  scroll-behavior: smooth;
  scroll-padding-top: 98px;
  -webkit-tap-highlight-color: rgb(20 89 166 / 14%);
}

*, *::before, *::after { box-sizing: border-box; }
body { margin: 0; min-width: 320px; background: var(--page); }
a { color: var(--blue); text-decoration-thickness: 1px; text-underline-offset: 4px; }
a:hover { color: #0c417a; }
button, summary, a { touch-action: manipulation; }
button, select { font: inherit; }
button:focus-visible, a:focus-visible, summary:focus-visible { outline: 3px solid #236bb7; outline-offset: 4px; }
::selection { background: #d3e6f8; color: #10263a; }

.skip-link { position: absolute; z-index: 20; top: 8px; left: 8px; padding: 8px 12px; transform: translateY(-150%); background: var(--paper); color: var(--ink); }
.skip-link:focus { transform: translateY(0); }
.topbar { position: sticky; z-index: 10; top: 0; display: flex; min-height: 74px; align-items: center; justify-content: space-between; gap: 26px; padding: 0 max(32px, calc((100vw - 1320px) / 2)); border-bottom: 1px solid var(--rule); background: rgb(255 255 255 / 96%); backdrop-filter: blur(12px); }
.brand { display: inline-flex; flex: 0 0 auto; align-items: center; gap: 11px; color: var(--ink); text-decoration: none; }
.brand:hover { color: var(--ink); }
.brand-mark { display: grid; width: 38px; height: 38px; place-items: center; border: 1px solid var(--ink); border-radius: 50%; font-family: Georgia, serif; font-size: 28px; line-height: 1; font-style: italic; }
.brand strong, .brand small { display: block; line-height: 1.3; }
.brand strong { font-size: 15px; letter-spacing: .01em; }
.brand small { margin-top: 3px; color: var(--muted); font-size: 11px; }
.topbar nav { display: flex; align-items: center; gap: clamp(14px, 2.1vw, 32px); }
.topbar nav a { color: var(--body); font-size: 13px; font-weight: 600; text-decoration: none; white-space: nowrap; }
.topbar nav a:hover { color: var(--blue); }
.topbar nav .nav-library { padding: 8px 12px; border: 1px solid var(--rule); background: var(--paper); }

.hero { position: relative; display: grid; max-width: 1440px; min-height: 622px; grid-template-columns: minmax(0, 1.05fr) minmax(310px, .95fr); align-items: center; gap: clamp(42px, 8vw, 130px); margin: 0 auto; padding: 76px max(7.3vw, 48px) 80px; overflow: hidden; }
.hero::before { position: absolute; z-index: -1; top: 0; right: 0; width: 48%; height: 100%; background-color: #edf2f5; background-image: linear-gradient(rgb(34 71 105 / 5%) 1px, transparent 1px), linear-gradient(90deg, rgb(34 71 105 / 5%) 1px, transparent 1px); background-size: 32px 32px; content: ""; clip-path: polygon(19% 0, 100% 0, 100% 100%, 0 100%); }
.hero-kicker, .section-label { margin: 0 0 16px; color: var(--blue); font-size: 13px; font-weight: 700; letter-spacing: .06em; }
h1, h2, h3, h4, p, figure { margin-top: 0; }
h1, h2, h3, h4 { color: var(--ink); }
.hero h1 { max-width: 680px; margin-bottom: 21px; font-size: clamp(46px, 5.6vw, 76px); line-height: 1.13; letter-spacing: -.045em; text-wrap: balance; }
.hero h1 span { color: var(--blue); }
.hero-lead { max-width: 600px; margin-bottom: 13px; color: var(--ink); font-size: clamp(20px, 2vw, 25px); font-weight: 550; line-height: 1.58; text-wrap: pretty; }
.hero-context { max-width: 590px; margin-bottom: 25px; color: var(--muted); font-size: 15px; }
.hero-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 20px; }
.button-primary, .button-secondary { display: inline-flex; min-height: 47px; align-items: center; justify-content: center; padding: 10px 17px; border: 1px solid var(--blue); background: var(--blue); color: #fff; font-size: 14px; font-weight: 650; text-decoration: none; }
.button-primary:hover, .button-secondary:hover { border-color: #0c417a; background: #0c417a; color: #fff; }
.button-secondary { border-color: var(--rule); background: var(--paper); color: var(--ink); }
.button-secondary:hover { border-color: var(--blue); background: var(--blue-light); color: var(--ink); }
.button-quiet { font-size: 14px; font-weight: 600; }
.source-note { max-width: 580px; margin: 17px 0 0; color: var(--muted); font-size: 12px; }
.hero-equation { position: relative; display: flex; min-height: 328px; flex-direction: column; justify-content: center; margin: 28px 0 0; padding: 39px clamp(25px, 4vw, 58px); border: 1px solid #c4d0db; background: var(--paper); box-shadow: 9px 9px 0 #dfe6eb; transform: rotate(1deg); }
.hero-equation::before { position: absolute; top: 29px; bottom: 28px; left: 17px; width: 3px; background: var(--blue); content: ""; }
.equation-cap { margin-bottom: 21px; color: var(--muted); font-size: 12px; font-weight: 650; }
.equation-line { padding: 11px 0; border-bottom: 1px solid #e6ebef; color: var(--ink); font-family: Georgia, "Times New Roman", serif; font-size: clamp(22px, 2.3vw, 31px); letter-spacing: .035em; }
.equation-result { display: flex; align-items: baseline; gap: 15px; padding-top: 23px; color: var(--red); }
.equation-result span { font-size: 13px; }
.equation-result strong { font-family: Georgia, "Times New Roman", serif; font-size: 31px; }
.hero-equation figcaption { margin-top: 25px; color: var(--muted); font-size: 12px; }

.section-wrap { max-width: var(--measure); margin: 0 auto; padding: 86px 42px; }
.case-section { max-width: none; padding-right: max(42px, calc((100vw - 1080px) / 2)); padding-left: max(42px, calc((100vw - 1080px) / 2)); background: var(--paper); }
.section-heading, .split-heading { display: flex; align-items: end; justify-content: space-between; gap: 40px; margin-bottom: 22px; }
.section-heading h2, .split-heading h2, .progress-heading h2 { max-width: 720px; margin-bottom: 0; font-size: clamp(34px, 4vw, 50px); font-weight: 620; line-height: 1.22; letter-spacing: -.035em; text-wrap: balance; }
.section-heading .text-link { flex: 0 0 auto; margin-bottom: 7px; font-size: 13px; }
.small-break { display: none; }
.case-provenance { max-width: 800px; margin: 16px 0 56px; padding: 13px 16px; border-left: 3px solid var(--amber); background: var(--amber-light); color: #4f3b17; font-size: 14px; }
.case-body { display: grid; grid-template-columns: 46px minmax(0, 1fr); gap: 24px; }
.case-rail { position: relative; display: flex; justify-content: center; }
.case-rail::before { position: absolute; top: 0; bottom: 0; width: 1px; background: var(--rule); content: ""; }
.case-rail span { position: sticky; top: 110px; z-index: 1; width: 9px; height: 9px; margin-top: 23px; border: 2px solid var(--paper); border-radius: 50%; background: var(--blue); box-shadow: 0 0 0 1px var(--blue); }
.case-stages { min-width: 0; }
.case-stage { position: relative; display: grid; grid-template-columns: 124px minmax(0, 1fr); gap: 24px; padding: 0 0 57px; }
.case-stage + .case-stage { padding-top: 15px; }
.stage-marker { display: flex; justify-content: flex-start; }
.stage-marker span { position: sticky; top: 104px; align-self: flex-start; padding-top: 7px; color: var(--blue); font-size: 12px; font-weight: 720; letter-spacing: .035em; }
.stage-content { max-width: 820px; min-width: 0; }
.stage-content h3 { margin-bottom: 9px; font-size: clamp(22px, 2.5vw, 29px); font-weight: 640; letter-spacing: -.025em; }
.stage-title-row { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 9px 16px; }
.stage-title-row h3 { margin: 0; }
.evidence-tag { display: inline-flex; align-items: center; padding: 3px 8px; color: var(--muted); font-size: 11px; font-weight: 700; white-space: nowrap; }
.tag-constructed { background: var(--amber-light); color: var(--amber); }
.tag-recorded { background: var(--blue-light); color: #163f68; }
.stage-intro { max-width: 760px; margin: 12px 0 21px; color: var(--body); font-size: 15px; }
.problem-sheet { padding: 20px clamp(17px, 3vw, 32px) 24px; border: 1px solid var(--rule); background: #fff; }
.sheet-heading { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 4px 15px; padding-bottom: 10px; border-bottom: 1px solid var(--rule); color: var(--muted); font-size: 12px; }
.problem-sheet > p { max-width: 700px; margin: 20px 0 24px; color: var(--ink); font-size: 20px; }
.answer-margin { display: grid; grid-template-columns: 100px minmax(0, 1fr); gap: 10px; padding-top: 13px; border-top: 1px dashed #c9d2da; }
.answer-margin > span { padding-top: 6px; color: var(--red); font-size: 12px; font-weight: 700; }
.answer-margin pre { margin: 0; overflow-wrap: anywhere; white-space: pre-wrap; color: var(--ink); font-family: inherit; font-size: 15px; line-height: 1.8; }
.reader-note { max-width: 760px; margin: 15px 0 0; color: var(--muted); font-size: 13px; }
.diagnosis-result { display: grid; gap: 13px; margin: 20px 0; }
.diagnosis-step { padding: 15px 18px; border-left: 3px solid var(--red); background: var(--red-light); }
.diagnosis-step.is-dependent { border-left-color: #7c8b97; background: #f1f4f6; }
.diagnosis-step h4 { margin-bottom: 6px; font-size: 14px; }
.diagnosis-step p { margin: 0 0 8px; font-size: 14px; }
.diagnosis-step p:last-child { margin-bottom: 0; }
.evidence-quote { color: var(--red); font-weight: 650; }
.text-link { display: inline-block; margin-top: 12px; font-size: 13px; font-weight: 650; }
details { border-top: 1px solid var(--rule); }
summary { padding: 12px 3px; color: var(--ink); cursor: pointer; font-size: 14px; font-weight: 650; }
summary:hover { color: var(--blue); }
.comparison-fold { margin-top: 18px; }
.comparison-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; padding: 8px 0 15px; }
.comparison-grid h4 { margin-bottom: 6px; font-size: 13px; }
.comparison-grid p { margin: 0; overflow-wrap: anywhere; color: var(--body); font-size: 13px; white-space: pre-wrap; }
.teaching-summary { margin: 18px 0 10px; padding: 18px 20px; border: 1px solid var(--rule); background: #fbfcfd; }
.teaching-summary .frame-count { margin-bottom: 6px; color: var(--blue); font-size: 12px; font-weight: 700; }
.teaching-summary blockquote { margin: 0; color: var(--ink); font-size: 16px; }
.frame-list { margin: 0 0 15px; padding-left: 23px; }
.frame-list li { padding: 8px 0 8px 7px; border-bottom: 1px solid #e6ebef; }
.frame-list li::marker { color: var(--blue); font-variant-numeric: tabular-nums; }
.frame-input { display: block; margin-bottom: 4px; color: var(--muted); font-size: 12px; }
.frame-output { display: block; margin: 0; color: var(--body); font-size: 14px; white-space: pre-wrap; overflow-wrap: anywhere; }
.frame-list .hint-warning { margin-top: 10px; padding: 10px; background: var(--amber-light); color: #4f3b17; font-size: 12px; list-style: none; }
.quality-note { margin: 15px 0; padding: 12px 15px; background: var(--amber-light); color: #4f3b17; font-size: 13px; }
.variant-question { margin: 17px 0 13px; padding: 17px 20px; border-left: 3px solid var(--blue); background: var(--blue-light); color: var(--ink); font-size: 17px; }
.variant-check { color: var(--body); font-size: 14px; }
.math-rendered-display { display: block; overflow-x: auto; padding: 2px 0; }
.math-rendered { overflow-wrap: anywhere; }
.evidence-columns { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(20px, 5vw, 60px); margin: 22px 0; }
.evidence-columns > div:first-child { border-top: 2px solid var(--blue); }
.evidence-columns > div:last-child { border-top: 2px solid var(--amber); }
.evidence-columns h4 { margin: 12px 0 6px; font-size: 14px; }
.evidence-columns p { margin: 0; color: var(--muted); font-size: 13px; }

.teaching-section { padding-top: 98px; padding-bottom: 104px; }
.split-heading { align-items: start; margin-bottom: 39px; }
.split-heading > p { max-width: 430px; margin: 6px 0 0; color: var(--muted); font-size: 14px; }
.learning-path { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); }
.learning-path a { position: relative; display: flex; min-height: 170px; flex-direction: column; justify-content: center; gap: 7px; padding: 20px clamp(13px, 2vw, 25px); color: var(--body); text-decoration: none; }
.learning-path a + a { border-left: 1px solid var(--rule); }
.learning-path a::after { position: absolute; top: 50%; right: -5px; z-index: 1; width: 8px; height: 8px; border-top: 1px solid var(--rule); border-right: 1px solid var(--rule); background: var(--page); content: ""; transform: translateY(-50%) rotate(45deg); }
.learning-path a:last-child::after { display: none; }
.learning-path a:hover { background: var(--paper); }
.learning-path span { color: var(--muted); font-size: 12px; }
.learning-path strong { color: var(--ink); font-size: 16px; }
.learning-path em { align-self: flex-start; margin-top: 5px; padding: 2px 7px; background: var(--blue-light); color: #244c70; font-size: 11px; font-style: normal; }
.learning-path a:last-child em { background: #eceff1; color: #4a5b69; }
.path-caption { margin: 13px 0 0; color: var(--muted); font-size: 12px; }

.research-section { max-width: none; background: #eaf0f4; }
.research-heading { max-width: 1100px; margin: 0 auto 34px; align-items: end; }
.research-heading .text-link { flex: 0 0 auto; font-size: 13px; }
.research-ledger { display: grid; max-width: 1100px; grid-template-columns: repeat(3, minmax(0, 1fr)); margin: 0 auto; border-top: 1px solid #b9c7d1; border-bottom: 1px solid #b9c7d1; }
.research-ledger article { position: relative; min-height: 204px; padding: 24px 25px 22px 31px; }
.research-ledger article + article { border-left: 1px solid #b9c7d1; }
.ledger-rule { position: absolute; top: 26px; left: 0; width: 3px; height: 34px; background: var(--blue); }
.research-ledger h3 { margin-bottom: 9px; font-size: 16px; }
.research-ledger p { min-height: 70px; margin-bottom: 14px; color: var(--muted); font-size: 13px; }
.research-ledger a { font-size: 12px; font-weight: 650; }

.progress-section { padding-top: 100px; padding-bottom: 105px; }
.progress-heading { margin-bottom: 25px; }
.progress-heading .section-label { margin-bottom: 12px; }
.progress-heading h2 { max-width: 700px; font-size: clamp(30px, 3.5vw, 42px); }
.status-list { max-width: 940px; margin-bottom: 24px; border-top: 1px solid var(--rule); }
.status-list > div { display: grid; grid-template-columns: 15px 130px minmax(0, 1fr); align-items: baseline; gap: 10px 16px; padding: 15px 0; border-bottom: 1px solid var(--rule); }
.status-list strong { color: var(--ink); font-size: 14px; }
.status-list p { margin: 0; color: var(--muted); font-size: 13px; }
.status-dot { display: inline-block; width: 9px; height: 9px; align-self: center; border-radius: 50%; }
.dot-blue { background: var(--blue); }
.dot-amber { background: #9a6a17; }
.dot-gray { background: #7c8994; }
.site-footer { display: flex; min-height: 110px; align-items: center; justify-content: space-between; gap: 22px; padding: 23px max(42px, calc((100vw - 1180px) / 2)); border-top: 1px solid var(--rule); background: var(--paper); }
.site-footer p { margin: 0 auto 0 10px; color: var(--muted); font-size: 13px; }
.site-footer > a:not(.brand) { font-size: 12px; }
.footer-distinction { color: var(--muted); font-size: 11px; white-space: nowrap; }
.footer-brand .brand-mark { width: 32px; height: 32px; font-size: 23px; }
.noscript { margin: 0; padding: 15px 24px; background: var(--amber-light); color: #4f3b17; text-align: center; font-size: 13px; }

/* The reference catalogue uses headings and openable records rather than a second sales page. */
.topics-page { background: var(--paper); }
.topics-top { position: sticky; z-index: 10; top: 0; display: flex; min-height: 68px; align-items: center; justify-content: space-between; gap: 16px; padding: 8px max(26px, calc((100vw - 1280px) / 2)); border-bottom: 1px solid var(--rule); background: rgb(255 255 255 / 97%); }
.topics-top .topic-links { display: flex; max-width: 82vw; gap: 14px; overflow-x: auto; padding: 6px; }
.topics-top .topic-links a, .topics-top > a:last-child { flex: 0 0 auto; font-size: 12px; font-weight: 600; text-decoration: none; }
.topics-content { max-width: 1080px; margin: 0 auto; padding: 52px 32px 100px; }
.topics-intro { max-width: 760px; margin: 0 0 52px; }
.topics-intro h1 { margin-bottom: 9px; font-size: clamp(34px, 5vw, 52px); letter-spacing: -.035em; }
.topics-intro p { margin: 0; color: var(--muted); }
.topic-group { scroll-margin-top: 90px; margin: 0 0 63px; }
.topic-group > header { display: flex; align-items: baseline; justify-content: space-between; gap: 20px; margin-bottom: 19px; border-bottom: 2px solid var(--ink); }
.topic-group > header h2 { margin: 0; padding-bottom: 9px; font-size: 24px; }
.topic-group > header p { margin: 0 0 8px; color: var(--muted); font-size: 12px; }
.topic-article { padding: 26px 0 31px; border-bottom: 1px solid var(--rule); scroll-margin-top: 100px; }
.topic-article h3 { margin-bottom: 7px; font-size: 21px; }
.topic-thesis { max-width: 760px; margin-bottom: 17px; color: var(--blue); font-size: 16px; font-weight: 600; }
.topic-status { display: inline-block; margin: 0 0 14px; padding: 3px 7px; background: #eef2f4; color: #455867; font-size: 11px; font-weight: 650; }
.topic-pain { max-width: 800px; padding: 14px 17px; border-left: 3px solid var(--red); background: var(--red-light); }
.topic-pain strong { display: block; margin-bottom: 4px; color: #89312b; font-size: 13px; }
.topic-pain p, .topic-copy p, .topic-details p { max-width: 800px; margin-bottom: 11px; }
.topic-pain p:last-child, .topic-copy p:last-child, .topic-details p:last-child { margin-bottom: 0; }
.topic-column { max-width: 850px; }
.topic-mechanism { margin: 17px 0; padding-left: 21px; }
.topic-mechanism li { margin-bottom: 6px; padding-left: 4px; }
.topic-mechanism li::marker { color: var(--blue); }
.topic-details { max-width: 850px; }
.topic-details details, .research-detail details { margin-top: 8px; }
.research-detail { max-width: 900px; margin-top: 25px; padding-top: 10px; border-top: 1px dashed var(--rule); }
.research-detail > h4 { margin: 7px 0; color: var(--muted); font-size: 12px; }
.study-card { padding: 14px 0 12px; border-bottom: 1px solid #e1e7eb; }
.study-card h5 { margin: 0 0 6px; color: var(--ink); font-size: 15px; }
.study-card .study-links { display: flex; gap: 15px; margin-bottom: 8px; font-size: 12px; }
.study-facts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 9px 24px; margin: 8px 0; }
.study-facts div { padding-left: 10px; border-left: 2px solid #d4dce2; }
.study-facts dt { margin-bottom: 2px; color: var(--muted); font-size: 11px; font-weight: 700; }
.study-facts dd { margin: 0; font-size: 12px; }
.study-scope { color: var(--amber); }
.highlight-record { display: grid; grid-template-columns: 130px minmax(0, 1fr); gap: 20px; padding: 18px 0; border-bottom: 1px solid var(--rule); }
.highlight-record h3 { margin: 0; font-size: 16px; }
.highlight-record p { max-width: 780px; margin: 0 0 10px; }
.highlight-record .highlight-title { color: var(--ink); font-size: 18px; font-weight: 650; }
.highlight-record .highlight-pain { color: var(--red); font-size: 13px; font-weight: 600; }
.vision-group { margin: 18px 0; padding: 15px 18px; background: #f5f7f8; }
.vision-group summary { font-size: 17px; }
.vision-row { display: grid; grid-template-columns: minmax(0, .9fr) minmax(0, 1.1fr); gap: 23px; padding: 17px 5px; border-top: 1px solid var(--rule); }
.vision-row h4 { grid-column: 1 / -1; margin: 0 0 -14px; color: var(--blue); font-size: 13px; }
.vision-row p { margin: 0; font-size: 13px; }
.vision-row p strong { display: block; margin-bottom: 5px; color: var(--muted); font-size: 11px; }
.vision-links { display: flex; flex-wrap: wrap; gap: 8px 15px; padding: 0 5px 14px; font-size: 12px; }
.vision-manifesto { margin-top: 42px; padding: 22px 25px; border-left: 3px solid var(--blue); background: #edf2f5; color: var(--ink); }
.vision-manifesto blockquote { max-width: 750px; margin: 0; font-size: 20px; font-weight: 600; }
.math-page-footer { display: flex; justify-content: space-between; gap: 15px; padding: 22px max(30px, calc((100vw - 1080px) / 2)); border-top: 1px solid var(--rule); color: var(--muted); font-size: 12px; }
.math-page-footer a { font-weight: 650; }

@media (max-width: 1020px) {
  .topbar { padding-right: 24px; padding-left: 24px; }
  .topbar nav { max-width: 65vw; gap: 15px; overflow-x: auto; padding: 8px 3px; }
  .topbar nav a { font-size: 12px; }
  .hero { min-height: 570px; gap: 32px; padding-right: 5vw; padding-left: 5vw; }
  .hero-equation { min-height: 300px; }
  .section-wrap { padding-right: 30px; padding-left: 30px; }
  .case-section { padding-right: 30px; padding-left: 30px; }
}

@media (max-width: 720px) {
  :root { font-size: 15px; scroll-padding-top: 118px; }
  .topbar { min-height: 102px; flex-direction: column; align-items: stretch; justify-content: center; gap: 7px; padding: 9px 17px 0; }
  .brand-mark { width: 32px; height: 32px; font-size: 24px; }
  .brand strong { font-size: 14px; }
  .brand small { font-size: 10px; }
  .topbar nav { max-width: none; gap: 21px; padding: 9px 0 10px; }
  .topbar nav a { font-size: 12px; }
  .topbar nav .nav-library { padding: 4px 8px; }
  .hero { min-height: auto; grid-template-columns: minmax(0, 1fr); gap: 28px; padding: 53px 22px 46px; }
  .hero::before { top: 50%; width: 82%; height: 50%; }
  .hero-kicker, .section-label { margin-bottom: 11px; font-size: 12px; }
  .hero h1 { margin-bottom: 15px; font-size: clamp(42px, 11vw, 61px); }
  .hero-lead { font-size: 19px; }
  .hero-context { font-size: 14px; }
  .hero-equation { width: min(100%, 470px); min-height: auto; margin: 8px auto 0; padding: 24px 28px 23px 40px; transform: rotate(.5deg); }
  .hero-equation::before { top: 20px; bottom: 18px; left: 17px; }
  .equation-cap { margin-bottom: 10px; }
  .equation-line { padding: 8px 0; font-size: 23px; }
  .equation-result { padding-top: 13px; }
  .equation-result strong { font-size: 25px; }
  .hero-equation figcaption { margin-top: 13px; }
  .section-wrap, .case-section { padding: 63px 21px; }
  .section-heading, .split-heading { display: block; margin-bottom: 25px; }
  .section-heading h2, .split-heading h2 { font-size: 34px; }
  .section-heading .text-link { margin-top: 14px; }
  .small-break { display: initial; }
  .case-provenance { margin-bottom: 38px; font-size: 13px; }
  .case-body { grid-template-columns: 21px minmax(0, 1fr); gap: 12px; }
  .case-stage { grid-template-columns: 1fr; gap: 5px; padding-bottom: 42px; }
  .case-stage + .case-stage { padding-top: 8px; }
  .stage-marker span { position: static; padding: 0; }
  .stage-content h3 { font-size: 22px; }
  .stage-title-row { align-items: flex-start; }
  .stage-title-row h3 { flex: 1 1 100%; }
  .stage-intro { margin: 10px 0 16px; font-size: 14px; }
  .problem-sheet { padding: 15px 14px 17px; }
  .problem-sheet > p { margin: 15px 0 19px; font-size: 17px; }
  .answer-margin { grid-template-columns: minmax(0, 1fr); gap: 2px; }
  .answer-margin pre { font-size: 14px; }
  .diagnosis-step { padding: 12px 13px; }
  .comparison-grid, .evidence-columns { grid-template-columns: minmax(0, 1fr); gap: 13px; }
  .learning-path { grid-template-columns: minmax(0, 1fr); }
  .learning-path a { min-height: 118px; padding: 16px 18px; }
  .learning-path a + a { border-top: 1px solid var(--rule); border-left: 0; }
  .learning-path a::after { top: auto; right: 22px; bottom: -5px; transform: rotate(135deg); }
  .split-heading > p { margin-top: 16px; }
  .research-heading .text-link { margin-top: 15px; }
  .research-ledger { grid-template-columns: minmax(0, 1fr); }
  .research-ledger article { min-height: auto; padding: 19px 17px 19px 25px; }
  .research-ledger article + article { border-top: 1px solid #b9c7d1; border-left: 0; }
  .research-ledger p { min-height: auto; }
  .status-list > div { grid-template-columns: 12px minmax(0, 1fr); gap: 4px 10px; }
  .status-list p { grid-column: 2; }
  .site-footer { flex-wrap: wrap; padding: 23px 21px; }
  .site-footer p { flex-basis: 50%; margin-left: 0; }
  .footer-distinction { margin-left: auto; }
  .topics-top { min-height: 96px; flex-wrap: wrap; padding: 7px 16px 2px; }
  .topics-top .topic-links { order: 2; max-width: 100%; gap: 17px; }
  .topics-top > a:last-child { margin-left: auto; }
  .topics-content { padding: 37px 20px 76px; }
  .topics-intro { margin-bottom: 38px; }
  .topics-intro h1 { font-size: 37px; }
  .topic-group { margin-bottom: 46px; }
  .topic-group > header { display: block; }
  .topic-group > header h2 { font-size: 21px; }
  .topic-group > header p { margin-top: 3px; }
  .topic-article h3 { font-size: 19px; }
  .study-facts { grid-template-columns: minmax(0, 1fr); }
  .highlight-record { grid-template-columns: minmax(0, 1fr); gap: 5px; }
  .vision-row { grid-template-columns: minmax(0, 1fr); gap: 11px; }
  .vision-row h4 { grid-column: auto; margin: 0; }
  .math-page-footer { flex-direction: column; padding: 20px; }
}

@media (prefers-reduced-motion: reduce) {
  :root { scroll-behavior: auto; }
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}