:root {
  --font-text: "Newsreader";
  --font-display: "Fraunces";
  --font-mono: "IBM Plex Mono";
  --paper: #fffffe;
  --paper-warm: #f5f3ef;
  --ink: #1b171a;
  --muted: #6b6569;
  --line: #d8d2d5;
  --magenta: #9e0fa3;
  --cyan: #176e9a;
  --green: #4f812f;
  --gold: #b88a13;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 88px; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--font-text), Georgia, serif;
  font-size: 18px;
  line-height: 1.66;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; }
.shell { width: min(1120px, calc(100% - 48px)); margin-inline: auto; }
.skip-link { position: fixed; top: -100px; left: 20px; z-index: 100; background: var(--ink); color: #fff; padding: 10px 16px; }
.skip-link:focus { top: 12px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  min-height: 68px;
  padding: 0 30px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--paper) 90%, transparent);
  backdrop-filter: blur(14px);
}
.wordmark { display: inline-flex; align-items: center; gap: 12px; font-family: var(--font-display), Georgia, serif; font-weight: 650; letter-spacing: .05em; text-transform: uppercase; font-size: 15px; white-space: nowrap; }
.wordmark-mark { position: relative; width: 20px; height: 20px; display: inline-block; border: 2px solid var(--cyan); transform: rotate(45deg); }
.wordmark-mark::before, .wordmark-mark::after { content: ""; position: absolute; border-radius: 50%; background: var(--magenta); }
.wordmark-mark::before { width: 6px; height: 6px; left: -4px; top: 5px; }
.wordmark-mark::after { width: 6px; height: 6px; right: -4px; bottom: 5px; background: var(--green); }
.site-header nav { display: flex; align-items: center; gap: clamp(16px, 2.8vw, 38px); font-family: var(--font-display), Georgia, serif; text-transform: uppercase; letter-spacing: .08em; font-size: 13px; }
.site-header nav a { border-bottom: 1px solid transparent; }
.site-header nav a:hover, .site-header nav a:focus-visible { border-color: var(--ink); }
.nav-download { color: var(--magenta); }

.hero { padding: 112px 0 84px; }
.eyebrow { margin: 0 0 26px; color: var(--muted); font-family: var(--font-mono), monospace; font-size: 12px; font-weight: 600; letter-spacing: .13em; text-transform: uppercase; }
.hero h1 { margin: 0; max-width: 1080px; font-family: var(--font-display), Georgia, serif; font-size: clamp(66px, 9.2vw, 132px); font-weight: 470; line-height: .92; letter-spacing: -.045em; }
.hero h1 em, .section-heading h2 em { color: var(--magenta); font-weight: 360; }
.hero-meta { margin-top: 50px; display: flex; flex-wrap: wrap; align-items: baseline; gap: 20px; }
.author { margin: 0; font-family: var(--font-display), Georgia, serif; font-size: clamp(22px, 2.8vw, 29px); font-weight: 560; }
.edition-note { margin: 0; color: var(--muted); font-style: italic; }
.concept-ribbons { margin-top: 36px; display: flex; flex-wrap: wrap; gap: 11px; }
.concept-ribbon { position: relative; display: inline-flex; align-items: baseline; gap: 10px; padding: 8px 22px 8px 18px; color: #fff; background: var(--ribbon); font-family: var(--font-mono), monospace; font-size: 12px; letter-spacing: .04em; box-shadow: 4px 5px 0 color-mix(in srgb, var(--ribbon) 38%, #777); clip-path: polygon(0 0, 94% 0, 100% 50%, 94% 100%, 0 100%, 3% 50%); }
.concept-ribbon b { font-size: 10px; opacity: .72; }
.hero-question { margin: 38px 0 0; max-width: 800px; color: var(--muted); font-family: var(--font-display), Georgia, serif; font-size: 20px; font-style: italic; }

.summary { min-height: 670px; padding: 90px 0 110px; display: grid; grid-template-columns: minmax(260px, 370px) 1fr; gap: clamp(46px, 7vw, 90px); align-items: center; }
.book-cover { position: relative; margin: 0; }
.book-cover::before { content: ""; position: absolute; inset: 18px -18px -18px 18px; z-index: -1; background: var(--cyan); }
.book-cover::after { content: ""; position: absolute; width: 72px; height: 72px; right: -44px; top: 14%; z-index: 2; border-radius: 50%; background: var(--magenta); mix-blend-mode: multiply; }
.book-cover img { display: block; width: 100%; border: 1px solid #262126; filter: saturate(.84) contrast(1.03); box-shadow: 0 24px 50px rgba(27, 23, 26, .2); }
.summary-copy h2 { margin: 0 0 30px; color: var(--magenta); font-family: var(--font-display), Georgia, serif; font-size: clamp(48px, 7vw, 78px); font-weight: 560; letter-spacing: -.03em; }
.summary-copy p { margin: 0 0 20px; max-width: 760px; font-size: clamp(20px, 2.2vw, 26px); line-height: 1.52; }
.actions { display: flex; flex-wrap: wrap; gap: 16px; margin-top: 42px; }
.button { display: inline-flex; min-height: 54px; align-items: center; justify-content: center; padding: 13px 30px; border: 1px solid var(--ink); font-family: var(--font-display), Georgia, serif; font-size: 14px; font-weight: 650; letter-spacing: .12em; text-transform: uppercase; transition: transform .18s ease, box-shadow .18s ease; }
.button:hover, .button:focus-visible { transform: translate(-2px,-2px); box-shadow: 5px 5px 0 var(--magenta); }
.button-dark { color: #fff; background: var(--ink); }
.button-light { background: var(--paper); }
.button-status { cursor: default; }

.numbered-section { padding: 105px 0; }
.section-heading { display: flex; align-items: center; gap: 25px; margin-bottom: 52px; }
.section-number { width: 64px; height: 76px; flex: 0 0 auto; display: grid; place-items: center; color: #fff; background: var(--magenta); font-family: var(--font-display), Georgia, serif; font-size: 42px; font-weight: 560; transform: rotate(-4deg); box-shadow: 8px 8px 0 #e3ddd2; }
.section-number.blue { background: var(--cyan); }
.section-number.green { background: var(--green); }
.section-number.gold { background: var(--gold); }
.section-number.burgundy { background: var(--magenta); }
.section-heading h2 { margin: 0; max-width: 950px; font-family: var(--font-display), Georgia, serif; font-size: clamp(44px, 6.2vw, 72px); font-weight: 470; line-height: 1.04; letter-spacing: -.03em; }
.finding-card { padding: 30px 34px 38px; border: 1px solid var(--line); background: var(--paper-warm); box-shadow: 0 15px 38px rgba(43,39,31,.08); }
.finding-label { display: flex; align-items: center; gap: 10px; margin-bottom: 26px; font-family: var(--font-mono), monospace; color: var(--muted); font-size: 12px; font-weight: 600; letter-spacing: .12em; text-transform: uppercase; }
.finding-label span { width: 13px; height: 13px; background: var(--cyan); transform: rotate(-7deg); }
.finding-flow { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr; gap: 16px; align-items: center; }
.finding-flow div { display: flex; flex-direction: column; min-height: 126px; padding: 20px; border-left: 5px solid var(--magenta); background: var(--paper); }
.finding-flow div:nth-of-type(2) { border-color: var(--cyan); }
.finding-flow div:nth-of-type(3) { border-color: var(--green); }
.finding-flow div:nth-of-type(4) { border-color: var(--gold); }
.finding-flow small { color: var(--magenta); font-family: var(--font-mono), monospace; }
.finding-flow strong { margin-top: 9px; font-family: var(--font-display), Georgia, serif; font-size: 24px; }
.finding-flow span { color: var(--muted); font-size: 15px; line-height: 1.35; }
.finding-flow i { color: var(--magenta); font-style: normal; font-size: 28px; }
.section-prose { max-width: 820px; margin: 46px auto 0; font-size: 23px; line-height: 1.62; }
blockquote { max-width: 820px; margin: 40px auto 0; padding: 8px 0 8px 28px; border-left: 5px solid var(--magenta); color: var(--magenta); font-family: var(--font-display), Georgia, serif; font-size: 31px; font-style: italic; line-height: 1.35; }

.comparison-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.comparison-grid article { min-height: 300px; padding: 34px; border: 1px solid var(--line); background: #f3f1eb; }
.comparison-grid .accent-card { border-top: 8px solid var(--cyan); background: #faf9f4; box-shadow: 10px 12px 0 #d8e4e9; }
.card-kicker { margin: 0 0 12px; color: var(--muted); font-family: var(--font-mono), monospace; font-size: 12px; font-weight: 600; letter-spacing: .12em; text-transform: uppercase; }
.comparison-grid h3, .edition-card h3 { margin: 0 0 17px; font-family: var(--font-display), Georgia, serif; font-size: 34px; line-height: 1.1; }
.comparison-grid p { max-width: 470px; font-size: 19px; }
.cadence-line { height: 58px; margin-top: 30px; display: flex; align-items: flex-end; gap: 8px; }
.cadence-line span { display: block; width: 10px; background: var(--magenta); }
.cadence-line.fast span:nth-child(1) { height: 23px; } .cadence-line.fast span:nth-child(2) { height: 38px; } .cadence-line.fast span:nth-child(3) { height: 18px; } .cadence-line.fast span:nth-child(4) { height: 48px; } .cadence-line.fast span:nth-child(5) { height: 28px; } .cadence-line.fast span:nth-child(6) { height: 53px; }
.cadence-line.slow span { width: 34px; background: var(--cyan); } .cadence-line.slow span:nth-child(1) { height: 19px; } .cadence-line.slow span:nth-child(2) { height: 36px; } .cadence-line.slow span:nth-child(3) { height: 49px; } .cadence-line.slow span:nth-child(4) { height: 29px; }

.dark-section { max-width: none; color: #f5f1e8; background: var(--ink); }
.light-heading h2 { color: #fff; }
.light-heading h2 em { color: #6bd4ff; }
.dark-intro { max-width: 760px; margin: -15px 0 42px 90px; color: #ccc4c8; font-size: 23px; }
.boundary-scale { display: grid; grid-template-columns: 1fr 170px 1fr; align-items: stretch; }
.safe-zone, .risk-zone { padding: 34px; border: 1px solid #4a4448; background: #252025; }
.safe-zone > span, .risk-zone > span { font-family: var(--font-mono), monospace; font-size: 12px; letter-spacing: .12em; text-transform: uppercase; }
.safe-zone > span { color: #a9db91; } .risk-zone > span { color: #82d8ff; }
.safe-zone ul, .risk-zone ul { margin: 24px 0 0; padding: 0; list-style: none; font-family: var(--font-display), Georgia, serif; font-size: 23px; }
.safe-zone li, .risk-zone li { padding: 11px 0; border-top: 1px solid #494146; }
.boundary-mark { display: grid; place-items: center; padding: 24px 18px; color: var(--ink); background: #7fea4f; text-align: center; transform: skewY(-3deg); }
.boundary-mark span { font-family: var(--font-display), Georgia, serif; font-size: 19px; font-weight: 650; line-height: 1.3; transform: skewY(3deg); }

.intro-prose { margin: -18px 0 44px 88px; }
.chapter-list { border-top: 1px solid var(--line); }
.chapter-list article { display: grid; grid-template-columns: 95px 1fr; gap: 24px; padding: 27px 8px; border-bottom: 1px solid var(--line); }
.chapter-list article > span { color: var(--magenta); font-family: var(--font-mono), monospace; font-size: 13px; letter-spacing: .1em; }
.chapter-list h3 { margin: 0 0 5px; font-family: var(--font-display), Georgia, serif; font-size: 29px; font-weight: 560; text-transform: capitalize; }
.chapter-list p { max-width: 760px; margin: 0; color: var(--muted); }

.samples-section { padding: 112px 0 122px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); background: #eeecef; }
.samples-intro { max-width: 790px; margin: -18px 0 52px 88px; color: #484146; font-size: 23px; line-height: 1.58; }
.sample-list { display: grid; gap: 34px; }
.sample-card { overflow: hidden; border: 1px solid var(--ink); background: var(--paper); box-shadow: 12px 14px 0 #dccedf; }
.sample-card:nth-child(2) { box-shadow: 12px 14px 0 #c3dae5; }
.sample-card:nth-child(3) { box-shadow: 12px 14px 0 #cdddc4; }
.sample-card-header { display: flex; align-items: flex-start; justify-content: space-between; gap: 28px; padding: 32px 38px 27px; border-bottom: 1px solid var(--ink); }
.sample-card-header .card-kicker { color: var(--magenta); }
.sample-card:nth-child(2) .sample-card-header .card-kicker { color: var(--cyan); }
.sample-card:nth-child(3) .sample-card-header .card-kicker { color: var(--green); }
.sample-card-header h3 { margin: 0; font-family: var(--font-display), Georgia, serif; font-size: clamp(30px, 4vw, 45px); font-weight: 560; line-height: 1.08; letter-spacing: -.02em; }
.difficulty { flex: 0 0 auto; padding: 7px 12px; border: 1px solid currentColor; color: var(--magenta); font-family: var(--font-mono), monospace; font-size: 11px; font-weight: 600; letter-spacing: .12em; text-transform: uppercase; transform: rotate(2deg); }
.sample-card:nth-child(2) .difficulty { color: var(--cyan); transform: rotate(-2deg); }
.sample-card:nth-child(3) .difficulty { color: var(--green); }
.problem-block { padding: 34px 42px 39px; }
.problem-block > p:first-child { margin-top: 0; }
.problem-block p { max-width: 830px; }
.math-display { max-width: 100%; overflow-x: auto; overflow-y: hidden; padding: 4px 2px; color: #211c20; }
.math-display mjx-container { min-width: max-content; margin: .85em 0 !important; }
.alpha-list { max-width: 920px; margin: 26px 0 0; padding-left: 27px; }
.alpha-list li { padding: 7px 0 7px 10px; }
.alpha-list li::marker { color: var(--magenta); font-family: var(--font-mono), monospace; font-weight: 600; }
.solution-panel { border-top: 1px solid var(--ink); color: #f8f5ef; background: var(--ink); }
.solution-panel summary { min-height: 68px; padding: 18px 36px; display: flex; align-items: center; justify-content: space-between; gap: 24px; cursor: pointer; list-style: none; font-family: var(--font-display), Georgia, serif; font-size: 17px; font-weight: 650; letter-spacing: .09em; text-transform: uppercase; }
.solution-panel summary::-webkit-details-marker { display: none; }
.solution-panel summary:focus-visible { outline: 3px solid #6bd4ff; outline-offset: -5px; }
.solution-panel summary b { display: grid; width: 34px; height: 34px; place-items: center; border: 1px solid #817980; color: #6bd4ff; font-family: var(--font-mono), monospace; font-size: 24px; font-weight: 400; line-height: 1; transition: transform .18s ease, color .18s ease; }
.solution-panel[open] summary b { color: #a9db91; transform: rotate(45deg); }
.solution-body { padding: 34px 42px 44px; border-top: 1px solid #4a4448; }
.solution-body h4 { margin: 33px 0 8px; color: #6bd4ff; font-family: var(--font-mono), monospace; font-size: 13px; font-weight: 600; letter-spacing: .1em; text-transform: uppercase; }
.solution-body h4:first-child { margin-top: 0; }
.solution-body p { max-width: 860px; color: #d8d1d5; }
.solution-body .math-display { color: #fff; }
.result-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 13px; margin: 24px 0; }
.result-grid div { min-height: 92px; padding: 18px 20px; display: flex; flex-direction: column; justify-content: center; border-left: 5px solid var(--magenta); color: var(--ink); background: #f5f1ec; }
.result-grid div:nth-child(2) { border-color: var(--cyan); }
.result-grid div:nth-child(3) { border-color: var(--green); }
.result-grid small { color: var(--muted); font-family: var(--font-mono), monospace; font-size: 10px; font-weight: 600; letter-spacing: .1em; text-transform: uppercase; }
.result-grid strong { margin-top: 7px; font-family: var(--font-display), Georgia, serif; font-size: 20px; }

.editions-section { max-width: none; background: var(--paper-warm); }
.edition-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.edition-grid.three-up { grid-template-columns: repeat(3, 1fr); }
.edition-card { min-height: 330px; padding: 38px; border: 1px solid var(--ink); background: var(--paper); display: flex; flex-direction: column; }
.edition-card h3 { font-size: 38px; }
.edition-card p:not(.card-kicker) { max-width: 480px; font-size: 19px; }
.trade-card { box-shadow: 10px 12px 0 #ddc5df; }
.reference-card { box-shadow: 10px 12px 0 #c2d8e3; }
.verify-card { box-shadow: 10px 12px 0 #d0dfc5; }

.authors-section { padding: 120px 0; }
.authors-heading { margin-bottom: 56px; }
.author-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 26px; align-items: stretch; }
.author-card { display: flex; flex-direction: column; min-width: 0; padding: 22px 22px 30px; border: 1px solid var(--line); background: var(--paper-warm); }
.author-portrait { aspect-ratio: 1 / 1; margin: 0 0 26px; overflow: hidden; border: 1px solid var(--ink); background: #d7d5d4; }
.author-portrait img { width: 100%; height: 100%; display: block; object-fit: cover; filter: grayscale(1) contrast(1.08); }
.author-placeholder { display: grid; place-items: center; align-content: center; gap: 16px; color: #f4f1ef; background: repeating-linear-gradient(135deg, #1b171a 0 18px, #272126 18px 36px); }
.author-placeholder span { font-family: var(--font-display), Georgia, serif; font-size: clamp(64px, 7vw, 92px); line-height: 1; }
.author-placeholder small { color: #c9c4c7; font-family: var(--font-mono), monospace; font-size: 10px; letter-spacing: .14em; text-transform: uppercase; }
.sattinger-placeholder { background: repeating-linear-gradient(45deg, #1b171a 0 18px, #302a2e 18px 36px); }
.author-card h3 { margin: 0 0 18px; font-family: var(--font-display), Georgia, serif; font-size: clamp(31px, 3vw, 40px); line-height: 1.06; }
.author-card > p:last-child { margin: 0; color: #3f393d; font-size: 18px; line-height: 1.62; }
.author-card .placeholder-copy { color: var(--muted); font-family: var(--font-display), Georgia, serif; font-size: 23px; font-style: italic; }

.citation-section { padding: 95px 0; color: #f8f5ed; background: var(--magenta); }
.citation-layout { display: grid; grid-template-columns: .7fr 1.3fr; gap: 70px; align-items: center; }
.citation-section .eyebrow { color: #f0cbed; }
.citation-section h2 { margin: 0; font-family: var(--font-display), Georgia, serif; font-size: 57px; line-height: 1.05; }
pre { margin: 0; padding: 30px; overflow-x: auto; border: 1px solid rgba(255,255,255,.42); background: rgba(36,15,35,.2); white-space: pre-wrap; }
code { font-family: var(--font-mono), monospace; font-size: 13px; line-height: 1.7; }
footer { min-height: 110px; padding: 24px 30px; display: grid; grid-template-columns: 1fr auto 1fr; gap: 24px; align-items: center; border-top: 1px solid var(--line); }
footer p { margin: 0; color: var(--muted); font-size: 15px; text-align: center; }
footer > a:last-child { justify-self: end; font-family: var(--font-mono), monospace; font-size: 12px; text-transform: uppercase; }

@media (max-width: 980px) {
  .edition-grid.three-up, .author-grid { grid-template-columns: 1fr; }
  .author-card { display: grid; grid-template-columns: minmax(210px, 34%) 1fr; column-gap: 28px; align-items: start; }
  .author-card .author-portrait { grid-row: 1 / span 4; margin: 0; }
}

@media (max-width: 900px) {
  .site-header { padding: 14px 20px; align-items: flex-start; }
  .site-header nav { max-width: 62vw; overflow-x: auto; padding-bottom: 7px; }
  .site-header nav a:not(.nav-download) { display: none; }
  .hero { padding-top: 78px; }
  .summary { grid-template-columns: 1fr; gap: 58px; }
  .book-cover { width: min(390px, 88%); margin-inline: auto; }
  .finding-flow { grid-template-columns: 1fr; }
  .finding-flow i { transform: rotate(90deg); justify-self: center; }
  .comparison-grid, .edition-grid, .citation-layout { grid-template-columns: 1fr; }
  .boundary-scale { grid-template-columns: 1fr; }
  .boundary-mark { min-height: 120px; }
  .intro-prose, .dark-intro, .samples-intro { margin-left: 0; }
  footer { grid-template-columns: 1fr; text-align: center; }
  footer .wordmark, footer > a:last-child { justify-self: center; }
}

@media (max-width: 640px) {
  body { font-size: 17px; }
  .shell { width: min(100% - 30px, 1120px); }
  .site-header { min-height: 62px; }
  .wordmark { max-width: 55vw; overflow: hidden; text-overflow: ellipsis; font-size: 12px; }
  .wordmark-mark { width: 15px; height: 15px; flex: 0 0 auto; }
  .nav-download { font-size: 11px; }
  .hero { padding: 68px 0 58px; }
  .hero h1 { font-size: clamp(51px, 16vw, 78px); }
  .hero-meta { display: block; }
  .edition-note { margin-top: 8px; }
  .summary, .numbered-section, .authors-section { padding-top: 74px; padding-bottom: 74px; }
  .book-cover::after { right: -18px; }
  .section-heading { align-items: flex-start; gap: 16px; }
  .section-number { width: 48px; height: 58px; font-size: 31px; }
  .section-heading h2 { font-size: 41px; }
  .finding-card, .comparison-grid article, .edition-card { padding: 24px; }
  .section-prose { font-size: 20px; }
  blockquote { font-size: 25px; }
  .chapter-list article { grid-template-columns: 54px 1fr; }
  .chapter-list h3 { font-size: 24px; }
  .samples-section { padding: 74px 0 86px; }
  .samples-intro { margin-bottom: 38px; font-size: 20px; }
  .sample-list { gap: 27px; }
  .sample-card { box-shadow: 7px 9px 0 #dccedf; }
  .sample-card:nth-child(2) { box-shadow: 7px 9px 0 #c3dae5; }
  .sample-card:nth-child(3) { box-shadow: 7px 9px 0 #cdddc4; }
  .sample-card-header { padding: 25px 23px 22px; flex-direction: column; }
  .sample-card-header h3 { font-size: 31px; }
  .problem-block, .solution-body { padding: 27px 23px 31px; }
  .solution-panel summary { padding: 16px 22px; font-size: 14px; }
  .result-grid { grid-template-columns: 1fr; }
  .author-card { display: flex; }
  .author-card .author-portrait { width: 100%; margin-bottom: 24px; }
  .citation-section h2 { font-size: 43px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .button, .solution-panel summary b { transition: none; }
}