/* The study atlas: paper, ink, and three restrained annotation colours. */
.study-page {
  --study-ink: #1d3041;
  --study-muted: #58646d;
  --study-paper: #f4f0e8;
  --study-surface: #faf8f3;
  --study-line: #d9d5c9;
  --study-teal: #366963;
  --study-copper: #925538;
  --study-soft-teal: #e5eeea;
  color: var(--study-ink);
  background: var(--study-paper);
}
.study-page .topbar { max-width: 1440px; border-bottom: 1px solid var(--study-line); }
.study-page .brand, .study-page .brand strong { color: var(--study-ink); }
.study-page .brand-mark { background: var(--study-ink); }
.study-page .topbar-link:hover, .study-page .topbar-link.is-active { color: var(--study-teal); background: var(--study-soft-teal); }
.study-page .topbar-note { color: var(--study-muted); }
.study-page :is(a, button, input, summary):focus-visible { outline: 3px solid var(--study-copper); outline-offset: 3px; }
.study-page a, .study-page button, .study-page summary { touch-action: manipulation; }
.study-skip { position: fixed; z-index: 30; inset-block-start: -70px; inset-inline-start: 12px; background: var(--study-ink); color: white; padding: 12px 18px; text-decoration: none; }
.study-skip:focus { inset-block-start: 12px; }
.study-page .study-main { max-width: 1440px; padding: 0 44px 90px; }
.study-page .study-main > section { scroll-margin-top: 24px; }
.study-kicker, .section-overline { color: var(--study-copper); font-size: 12px; font-weight: 800; letter-spacing: .025em; }
.study-kicker { display: inline-flex; align-items: center; gap: 10px; margin: 0 0 24px; }
.kicker-line { width: 24px; height: 1px; background: currentColor; }
.study-hero { display: grid; grid-template-columns: minmax(0, 1.08fr) minmax(0, .92fr); align-items: stretch; gap: clamp(24px, 5vw, 84px); min-height: 565px; padding: 72px 0 75px; border-bottom: 1px solid var(--study-line); }
.hero-copy { display: flex; flex-direction: column; align-items: flex-start; justify-content: center; min-width: 0; }
.hero-copy h1 { margin: 0; color: var(--study-ink); font-size: clamp(48px, 5.3vw, 78px); font-weight: 750; line-height: 1.14; letter-spacing: -.065em; }
.hero-copy h1 em { color: var(--study-teal); font-style: normal; }
.hero-lede { max-width: 505px; color: #4f5e65; font-size: clamp(15px, 1.4vw, 18px); line-height: 1.85; margin: 24px 0 0; }
.hero-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 16px 26px; margin-top: 28px; }
.study-action { display: inline-flex; align-items: center; justify-content: center; gap: 30px; min-height: 48px; font-size: 14px; font-weight: 750; text-decoration: none; }
.study-action-primary { padding: 0 18px; color: #fff; background: var(--study-ink); border: 1px solid var(--study-ink); }
.study-action-primary:hover { background: var(--study-teal); border-color: var(--study-teal); }
.study-action-text { gap: 11px; color: var(--study-teal); border-bottom: 1px solid currentColor; }
.hero-path { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 57px; color: #927e6d; font-size: 11px; font-family: Georgia, 'Times New Roman', serif; direction: ltr; }
.hero-path span { white-space: nowrap; }
.hero-path b { color: var(--study-muted); font-family: 'Noto Sans Hebrew', Arial, sans-serif; font-weight: 650; margin-inline-start: 4px; }
.hero-path i { display: block; width: 25px; height: 1px; background: #b6b1a4; }
.hero-plate { position: relative; display: flex; flex-direction: column; justify-content: space-between; min-width: 0; min-height: 430px; overflow: hidden; isolation: isolate; padding: 25px 30px 23px; background: #e7e8df; border: 1px solid #d1d1c6; box-shadow: 14px 15px 0 #e8e2d5; }
.hero-plate::before { content: ''; position: absolute; inset: 0; z-index: -2; background-image: linear-gradient(to right, rgba(103, 114, 103, .085) 1px, transparent 1px),linear-gradient(to bottom, rgba(103, 114, 103, .085) 1px, transparent 1px); background-size: 30px 30px; }
.hero-plate::after { content: ''; position: absolute; inset: 0; z-index: -1; background: linear-gradient(135deg, rgba(231,232,223,.16), rgba(231,232,223,.9) 77%); }
.plate-top, .plate-bottom { display: flex; justify-content: space-between; align-items: center; gap: 12px; font: 700 10px/1.3 Georgia, 'Times New Roman', serif; letter-spacing: .1em; color: #5f7671; direction: ltr; }
.plate-bottom { direction: rtl; font-family: 'Noto Sans Hebrew', Arial, sans-serif; letter-spacing: 0; font-size: 11px; }
.plate-bottom span:last-child { font: 24px Georgia, serif; }
.plate-art { position: absolute; inset: 26px; z-index: -1; opacity: .73; }
.plate-orbit { position: absolute; display: block; border: 1px solid #8ba9a0; border-radius: 50%; transform: rotate(-31deg); }
.orbit-one { width: 210px; height: 115px; left: 2%; top: 13%; }
.orbit-two { width: 300px; height: 160px; left: 14%; top: 6%; }
.plate-axis { position: absolute; display: block; width: 1px; height: 215px; left: 47%; top: 0; transform: rotate(56deg); background: #b78b75; opacity: .7; }
.axis-two { transform: rotate(-53deg); background: #668b85; }
.plate-node { position: absolute; width: 8px; height: 8px; border-radius: 50%; background: #668b85; }
.node-one { left: 17%; top: 22%; }.node-two { left: 74%; top: 30%; }.node-three { left: 43%; top: 8%; background: var(--study-copper); }
.plate-cross { position: absolute; color: #61817c; font: 18px Georgia, serif; }
.cross-one { right: 19%; top: 8%; }.cross-two { right: 9%; top: 53%; }
.plate-content { position: relative; padding: 25px 0 31px; }
.plate-content p { margin: 0 0 16px; font-size: 14px; font-weight: 750; color: var(--study-teal); }
.plate-equation { max-width: 440px; color: var(--study-ink); font: 400 clamp(25px, 2.6vw, 37px)/1.28 'Cambria Math', 'STIX Two Math', Georgia, serif; letter-spacing: -.04em; overflow-wrap: anywhere; }
.plate-content > span { display: block; color: #60716c; margin-top: 21px; font-size: 13px; }
.study-section { padding: 84px 0 0; }
.study-section-heading { display: flex; justify-content: space-between; align-items: flex-end; gap: 24px; min-width: 0; margin-bottom: 33px; }
.study-section-heading > div { min-width: 0; }
.section-overline { margin: 0 0 12px; }
.study-section-heading h2 { color: var(--study-ink); margin: 0; font-size: clamp(29px, 3vw, 41px); font-weight: 750; line-height: 1.25; letter-spacing: -.055em; }
.study-section-heading p:not(.section-overline) { color: var(--study-muted); font-size: 14px; line-height: 1.8; margin: 10px 0 0; }
.section-side-note { flex: 0 0 auto; color: #9a988c; font: 10px Georgia, serif; letter-spacing: .12em; direction: ltr; white-space: nowrap; padding-bottom: 5px; }
.section-side-note span { color: var(--study-copper); font-size: 16px; vertical-align: middle; }
.formula-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1px; min-width: 0; background: var(--study-line); border: 1px solid var(--study-line); }
.formula-grid > * { min-width: 0; }
.formula-grid > :is(article, div, .formula-card) { background: var(--study-surface); padding: 25px 26px 27px; }
.formula-grid > :is(article, div, .formula-card):nth-child(2) { background: #ebeee9; }
.formula-grid :is(h3, strong) { color: var(--study-ink); }
.formula-grid h3 { margin: 0 0 14px; font-size: 17px; line-height: 1.4; }
.formula-grid p { color: var(--study-muted); line-height: 1.7; }
.formula-grid :is(.formula-equation, .equation, code) { display: block; color: var(--study-teal); font: 400 clamp(23px, 2.5vw, 34px)/1.5 'Cambria Math', 'STIX Two Math', Georgia, serif; direction: ltr; text-align: left; overflow-wrap: anywhere; }
.formula-grid :is(a, button) { display: inline-flex; align-items: center; min-height: 44px; color: var(--study-teal); font-weight: 700; }
.formula-grid .study-loading { grid-column: 1 / -1; margin: 0; background: var(--study-surface); padding: 26px; }
.diagram-section { padding-top: 93px; }
.diagram-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 20px; }
.concept-figure { min-width: 0; margin: 0; border-top: 1px solid var(--study-ink); }
.diagram-canvas { display: grid; place-items: center; height: 226px; overflow: hidden; margin-top: 15px; background: #edece3; }
.diagram-canvas svg { display: block; width: 100%; height: 100%; }
.concept-figure figcaption { display: grid; gap: 6px; padding: 19px 0 3px; }
.concept-index { color: var(--study-copper); font-size: 11px; font-weight: 800; }
.concept-figure figcaption strong { color: var(--study-ink); font-size: 19px; line-height: 1.35; }
.concept-figure figcaption > span:last-child { color: var(--study-muted); font-size: 13px; line-height: 1.7; }
.atlas-section { padding-top: 108px; }
.atlas-heading { margin-bottom: 28px; }
.study-toolbar { display: flex; align-items: center; flex-wrap: wrap; gap: 10px; min-height: 81px; padding: 16px 0; border-top: 1px solid var(--study-ink); border-bottom: 1px solid var(--study-line); }
.study-search-label { display: flex; align-items: center; gap: 10px; width: min(100%, 540px); height: 48px; padding: 0 15px; border: 1px solid #c9c8ba; background: #fbfaf6; }
.study-search-label:focus-within { border-color: var(--study-teal); box-shadow: inset 0 0 0 1px var(--study-teal); }
.search-glyph { color: var(--study-teal); font: 30px/1 Georgia, serif; margin-top: -5px; }
.study-search-label input { min-width: 0; width: 100%; height: 100%; border: 0; background: transparent; color: var(--study-ink); outline: 0; font-size: 16px; }
.study-search-label input::placeholder { color: #7d827d; }
.study-page .study-search-label input:focus-visible { outline: 0; }
.study-reset { min-height: 44px; border: 0; background: transparent; padding: 0 10px; color: var(--study-teal); font-size: 13px; font-weight: 750; white-space: nowrap; }
.study-reset span { font-size: 21px; vertical-align: -2px; margin-inline-start: 5px; }
.study-reset:hover { background: var(--study-soft-teal); }
.study-result-count { margin: 0 auto 0 0; color: var(--study-muted); font-size: 12px; white-space: nowrap; }
.atlas-workspace { display: grid; grid-template-columns: 230px minmax(0, 1fr); align-items: start; gap: 47px; padding-top: 34px; }
.unit-rail { position: sticky; top: 20px; min-width: 0; border-inline-start: 1px solid var(--study-line); padding-inline-start: 17px; }
.rail-title { display: flex; justify-content: space-between; gap: 8px; color: #626c65; font-size: 12px; font-weight: 800; margin: 0 0 13px; }
.unit-nav { display: grid; gap: 2px; }
.unit-nav :is(button, a) { display: flex; align-items: center; justify-content: space-between; gap: 8px; min-height: 45px; width: 100%; border: 0; border-radius: 0; padding: 8px 10px; color: #66736f; background: transparent; text-decoration: none; text-align: right; font-size: 13px; font-weight: 650; line-height: 1.4; }
.unit-nav :is(button, a):hover { color: var(--study-ink); background: #e9e9df; }
.unit-nav :is(.is-active, [aria-pressed="true"], [aria-current="true"]) { color: var(--study-teal); background: var(--study-soft-teal); box-shadow: inset -3px 0 var(--study-teal); font-weight: 800; }
.atlas-content { min-width: 0; }
.study-status { min-height: 20px; color: var(--study-muted); font-size: 12px; margin: 0 0 10px; }
.study-status:empty { display: none; }
.study-grid { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 17px; }
.study-card { min-width: 0; padding: 24px 25px; background: #fbfaf6; border: 1px solid var(--study-line); border-top: 3px solid var(--study-teal); box-shadow: 0 4px 0 rgba(53,74,63,.035); overflow-wrap: anywhere; }
.study-card:nth-child(4n+2), .study-card:nth-child(4n+3) { border-top-color: #b47a58; }
.study-card h3 { margin: 8px 0 12px; color: var(--study-ink); font-size: clamp(18px, 1.7vw, 23px); line-height: 1.35; letter-spacing: -.035em; }
.study-card :is(p, li, dd) { color: #516169; font-size: 13px; line-height: 1.8; }
.study-card p { margin: 10px 0; }
.study-card :is(small, .study-meta, .card-kicker, .card-unit, .study-card-unit) { color: var(--study-copper); font-size: 11px; font-weight: 750; }
.study-card :is(.equation, .formula, .math) { direction: ltr; unicode-bidi: isolate; font-family: 'Cambria Math', 'STIX Two Math', Georgia, serif; font-size: clamp(20px, 2vw, 29px); color: var(--study-ink); overflow-wrap: anywhere; }
.study-card :is(button, a) { display: inline-flex; align-items: center; min-height: 44px; max-width: 100%; color: var(--study-teal); font-size: 13px; font-weight: 750; }
.study-card a { text-underline-offset: 4px; }
.study-card button { border: 0; background: transparent; padding: 0 3px; text-align: right; }
.study-card button:hover, .study-card a:hover { color: var(--study-copper); }
.study-empty { padding: 50px 28px; border: 1px dashed #b9b7aa; background: #fbfaf6; text-align: center; }
.empty-mark { font: 38px Georgia, serif; color: var(--study-copper); }
.study-empty h3 { font-size: 21px; margin: 10px 0 6px; }
.study-empty p { font-size: 13px; color: var(--study-muted); }
.study-empty a { display: inline-flex; align-items: center; min-height: 44px; margin: 6px 9px; color: var(--study-teal); font-size: 13px; font-weight: 750; text-underline-offset: 4px; }
.study-empty[hidden], .study-empty [hidden], .formula-section[hidden], .challenge-section[hidden], .sources-section[hidden] { display: none !important; }
.challenge-section { margin-top: 92px; padding: 75px 0 80px; border-top: 1px solid var(--study-line); border-bottom: 1px solid var(--study-line); }
.section-link { display: inline-flex; align-items: center; gap: 11px; min-height: 44px; flex: 0 0 auto; color: var(--study-teal); text-decoration: none; border-bottom: 1px solid var(--study-teal); font-size: 13px; font-weight: 750; }
.section-link:hover { color: var(--study-copper); }
.book-question-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 18px; }
.book-question { display: flex; flex-direction: column; min-width: 0; padding: 25px; color: var(--study-ink); background: #e9ebe3; border: 1px solid #d4d8cc; border-inline-start: 3px solid var(--study-copper); overflow-wrap: anywhere; }
.book-question:nth-child(3n+2) { background: #f4eae0; border-color: #e3d8cc; }
.book-question :is(h3, h4) { margin: 6px 0 12px; font-size: 19px; line-height: 1.4; }
.book-question :is(p, li) { color: #556264; font-size: 13px; line-height: 1.75; }
.book-question :is(small, .book-meta, .question-meta) { color: var(--study-copper); font-size: 12px; font-weight: 800; }
.book-question :is(a, button) { display: inline-flex; align-items: center; min-height: 44px; color: var(--study-teal); font-weight: 750; font-size: 13px; margin-top: auto; }
.book-question button { background: transparent; border: 0; padding: 0; text-align: right; }
.sources-section { padding-top: 76px; }
.sources-section .study-section-heading { margin-bottom: 24px; }
.sources-details { border-top: 1px solid var(--study-ink); }
.sources-details summary { display: flex; justify-content: space-between; align-items: center; gap: 12px; min-height: 62px; padding: 10px 0; cursor: pointer; list-style: none; color: var(--study-ink); font-size: 15px; font-weight: 750; }
.sources-details summary::-webkit-details-marker { display: none; }
.summary-symbol { font-size: 24px; color: var(--study-teal); font-weight: 400; }
.sources-details[open] .summary-symbol { transform: rotate(45deg); }
.source-index { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 0 32px; padding-bottom: 20px; border-bottom: 1px solid var(--study-line); }
.source-index-item { min-width: 0; padding: 19px 0; border-top: 1px solid var(--study-line); overflow-wrap: anywhere; }
.source-index-item :is(h3, strong) { color: var(--study-ink); }
.source-index-item h3 { margin: 0 0 6px; font-size: 16px; }
.source-index-item :is(p, span, small) { color: var(--study-muted); font-size: 12px; line-height: 1.65; }
.source-index-item :is(a, button) { display: inline-flex; align-items: center; min-height: 44px; color: var(--study-teal); font-weight: 750; font-size: 12px; }
.source-index-item button { border: 0; background: transparent; padding: 0; text-align: right; }
/* Rendered study data: keep long formulas and source labels readable. */
#study-library { scroll-margin-top: 24px; }
.study-card { display: flex; flex-direction: column; }
.study-card-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
.study-card .study-card-unit { color: #934623; font-size: 12px; font-weight: 800; }
.study-frequency { color: #4f6058; font-size: 12px; white-space: nowrap; }
.study-frequency-note { max-width: 560px; padding: 9px 12px; border-inline-start: 2px solid var(--study-copper); color: #53626b !important; font-size: 12px !important; line-height: 1.6; }
.formula-intro { margin: 9px 0 0 !important; color: var(--study-ink) !important; font-size: 13px; line-height: 1.65; font-weight: 600; text-align: right; }
.study-equation { display: block; direction: ltr; unicode-bidi: isolate; max-width: 100%; min-width: 0; padding: 16px 0 18px; color: var(--study-teal); font-size: clamp(20px, 1.75vw, 24px); line-height: 1.55; text-align: left; overflow-x: auto; overflow-y: hidden; overflow-wrap: normal; letter-spacing: normal; }
.study-equation .katex-display { margin: 0; text-align: left; }
.study-equation .katex-display > .katex { font-size: 1em; text-align: left; white-space: nowrap; }
.study-equation-unavailable { direction: rtl; color: #744f3e; font: 600 13px/1.65 'Noto Sans Hebrew', sans-serif; text-align: right; }
.study-card-summary { margin-top: 5px !important; }
.study-when { padding: 12px 0; border-top: 1px solid var(--study-line); }
.study-when strong { color: var(--study-ink); }
.study-steps { margin: 4px 0 18px; padding-inline-start: 20px; }
.study-steps li { padding-inline-start: 4px; margin-bottom: 6px; }
.study-steps li::marker { color: var(--study-copper); font-family: Georgia, serif; }
.study-card-footer { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; margin-top: auto; padding-top: 16px; border-top: 1px solid var(--study-line); }
.study-reference-label { min-width: 0; flex: 1 1 150px; color: #4f6058; font-size: 12px; line-height: 1.6; }
#formula-grid .study-card { min-height: 290px; border: 0; border-top: 3px solid var(--study-teal); box-shadow: none; }
#formula-grid .study-card:nth-child(3n+2) { border-top-color: var(--study-copper); }
#formula-grid .study-card h3 { font-size: 19px; margin-bottom: 7px; }
#formula-grid .study-equation { font-size: clamp(22px, 2.15vw, 28px); min-height: 84px; }
#formula-grid .study-card-summary { font-size: 13px; }
.study-card.is-deep-dive { grid-column: 1 / -1; background: #f7f6ef; }
#formula-grid .study-card.is-deep-dive { display: grid; grid-template-columns: minmax(0,.92fr) minmax(0,1.08fr); column-gap: 30px; padding: 31px 34px 33px; }
.is-deep-dive h3, #formula-grid .is-deep-dive h3 { font-size: clamp(23px, 2.2vw, 30px); }
.is-deep-dive > .study-equation { max-width: 440px; }
#formula-grid .is-deep-dive > :is(.study-card-heading, h3, .formula-intro, .study-card-summary, .study-when) { grid-column: 2; }
#formula-grid .is-deep-dive > .study-card-heading { grid-row: 1; }
#formula-grid .is-deep-dive > h3 { grid-row: 2; }
#formula-grid .is-deep-dive > .formula-intro { grid-row: 3; }
#formula-grid .is-deep-dive > .study-card-summary { grid-row: 4; }
#formula-grid .is-deep-dive > .study-when { grid-row: 5; }
#formula-grid .is-deep-dive > .study-equation { grid-column: 1; grid-row: 1 / 6; display: grid; align-content: center; justify-content: center; min-width: 0; max-width: none; padding: 24px; background: #e8efe9; border: 1px solid #c9d7ce; }
#formula-grid .is-deep-dive > :is(.guide-nav, .criteria-section, .study-method, .worked-example, .study-card-footer) { grid-column: 1 / -1; }
.guide-nav { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; padding-top: 16px; border-top: 1px solid var(--study-line); }
.study-card .guide-nav a { display: inline-flex; min-height: 44px; padding: 9px 13px; color: #255a54; background: #e6eeea; border: 1px solid #bfcec5; text-decoration: none; font-size: 13px; }
.study-card .guide-nav a:hover { background: #d9e8e1; }
.criteria-section, .study-method, .worked-example { scroll-margin-top: 24px; }
.criteria-section { margin-top: 23px; padding-top: 22px; border-top: 1px solid var(--study-line); }
.criteria-section h4, .method-title, .worked-example h4 { margin: 0 0 8px; color: var(--study-ink); font-size: 19px; line-height: 1.4; }
.study-card .criteria-lede { margin: 0 0 19px; font-size: 14px; }
.criteria-groups { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr)); gap: 12px; }
.criteria-group { min-width: 0; padding: 17px 18px 12px; background: #fffdf8; border: 1px solid #d7d8cb; border-top: 3px solid var(--study-teal); }
.criteria-group:nth-child(2) { border-top-color: #a35c37; background: #f4eee5; }
.criteria-group:nth-child(3) { border-top-color: #8a7354; }
.criteria-group h5 { margin: 0 0 11px; color: var(--study-ink); font-size: 15px; }
.criteria-list { list-style: none; margin: 0; padding: 0; }
.criterion { display: grid; grid-template-columns: 29px minmax(0,1fr); align-items: start; gap: 2px 11px; min-width: 0; padding: 12px 0; border-top: 1px solid #d7d8cb; }
.criterion-number { grid-row: span 3; display: grid; place-items: center; width: 27px; min-height: 27px; border: 1px solid #c6d3cc; color: #245b54; font: 800 13px/1 'Noto Sans Hebrew', sans-serif; }
.criterion-label { color: var(--study-ink); font-size: 14px; line-height: 1.6; font-weight: 650; }
.study-card .criterion-math { grid-column: 2; direction: ltr; unicode-bidi: isolate; max-width: 100%; min-width: 0; overflow-x: auto; color: var(--study-teal); font-size: 17px; line-height: 1.5; text-align: left; }
.criterion-math .katex-display, .worked-math .katex-display { margin: 0; text-align: left; }
.criterion-math .katex-display > .katex, .worked-math .katex-display > .katex { font-size: 1em; text-align: left; }
.study-card .criterion-note { grid-column: 2; color: #53626b; font-size: 12px; line-height: 1.6; font-weight: 500; }
.study-method { margin-top: 14px; padding-top: 17px; border-top: 1px solid var(--study-line); }
.study-card:not(.is-deep-dive) .method-title { font-size: 15px; }
.study-card .study-steps li { color: #354957; font-size: 14px; line-height: 1.7; margin-bottom: 10px; }
.is-deep-dive .study-steps li { color: #354957; font-size: 15px; line-height: 1.8; margin-bottom: 12px; }
.is-deep-dive .study-steps li::marker { color: #934623; font-weight: 800; }
.worked-example { min-width: 0; margin: 23px 0 19px; padding: 20px 22px; background: #e8efe9; border-inline-start: 3px solid var(--study-teal); }
.worked-example .example-setup { margin: 4px 0 13px; }
.example-row { display: grid; grid-template-columns: 70px minmax(0,1fr); gap: 8px; align-items: start; min-width: 0; padding: 10px 0; border-top: 1px solid #cbd8d1; }
.example-label { color: #345d59; font-size: 12px; font-weight: 800; }
.study-card .worked-math { direction: ltr; unicode-bidi: isolate; min-width: 0; max-width: 100%; overflow: visible; color: var(--study-ink); font-size: 20px; line-height: 1.45; text-align: left; }
.worked-example .example-conclusion { margin: 13px 0 0; color: var(--study-ink); font-size: 14px; line-height: 1.75; }
.book-question-index { color: var(--study-copper); font-size: 12px; font-weight: 800; line-height: 1.5; }
.book-question .book-question-prompt { margin: 0 0 16px; }
.book-question-hint { margin-top: auto; padding: 10px 0; border-top: 1px solid #cbd2c8; }
.book-question-hint summary { display: flex; align-items: center; min-height: 44px; color: var(--study-teal); cursor: pointer; font-size: 13px; font-weight: 750; }
.book-question-hint summary:hover { text-decoration: underline; text-underline-offset: 3px; }
.book-question-hint p { margin: 4px 0 8px; }
.book-question-links { display: flex; align-items: center; flex-wrap: wrap; gap: 5px 20px; border-top: 1px solid #cbd2c8; padding-top: 8px; }
.book-question-links a { text-underline-offset: 4px; }
.source-count { display: inline-flex; align-items: center; justify-content: center; min-width: 32px; min-height: 26px; padding: 0 7px; margin-inline-start: 8px; border: 1px solid var(--study-line); color: var(--study-teal); font: 700 12px Georgia, serif; }
.source-index-item { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.source-index-item > div { min-width: 0; display: grid; gap: 3px; }
.source-index-item .source-index-nickname { display: block; color: #53626b; font-size: 12px; }
.source-index-item > a { flex: 0 0 auto; text-underline-offset: 4px; }
.study-footer { max-width: 1440px; display: flex; justify-content: space-between; gap: 12px; margin: 0 auto; padding: 30px 44px 40px; border-top: 1px solid var(--study-line); color: #777d76; font-size: 12px; }
@media (max-width: 1100px) {
  .study-hero { gap: 30px; min-height: 490px; }
  .hero-copy h1 { font-size: clamp(46px, 5vw, 64px); }
  .hero-plate { min-height: 380px; }
  .atlas-workspace { gap: 25px; grid-template-columns: 200px minmax(0,1fr); }
  .book-question-grid { grid-template-columns: repeat(2,minmax(0,1fr)); }
}
@media (max-width: 800px) {
  #formula-grid .study-card.is-deep-dive { display: flex; flex-direction: column; }
  #formula-grid .is-deep-dive > .study-equation { display: block; min-height: 0; padding: 14px 0 18px; background: transparent; border: 0; }
  .study-page .study-main { padding-inline: 24px; }
  .study-hero { grid-template-columns: 1fr; gap: 34px; padding: 47px 0 55px; }
  .hero-copy { display: block; }
  .hero-path { margin-top: 32px; }
  .hero-plate { min-height: 325px; box-shadow: 8px 8px 0 #e8e2d5; }
  .formula-grid { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .diagram-grid { gap: 12px; }
  .diagram-canvas { height: 175px; }
  .atlas-workspace { grid-template-columns: 1fr; gap: 14px; padding-top: 17px; }
  .unit-rail { position: static; border: 0; padding: 0; }
  .rail-title { margin-bottom: 8px; }
  .unit-nav { display: flex; flex-wrap: wrap; gap: 6px; }
  .unit-nav :is(button, a) { width: auto; min-height: 44px; padding: 8px 13px; border: 1px solid var(--study-line); background: #fbfaf6; }
  .unit-nav :is(.is-active, [aria-pressed="true"], [aria-current="true"]) { border-color: var(--study-teal); box-shadow: none; }
  .study-toolbar { gap: 8px; }
  .study-result-count { margin-inline-start: 0; }
}
@media (max-width: 600px) {
  .study-page .study-main { padding-inline: 20px; padding-bottom: 60px; }
  .study-section { padding-top: 62px; }
  .study-hero { padding: 43px 0 54px; }
  .study-kicker { margin-bottom: 21px; }
  .hero-copy h1 { font-size: clamp(43px, 11vw, 55px); line-height: 1.18; }
  .hero-lede { font-size: 15px; line-height: 1.75; margin-top: 18px; }
  .hero-actions { margin-top: 24px; }
  .hero-path { margin-top: 31px; }
  .hero-plate { min-height: 300px; padding: 21px; }
  .plate-equation { font-size: clamp(24px, 6.8vw, 32px); }
  .study-section-heading { display: block; margin-bottom: 24px; }
  .study-section-heading h2 { font-size: 31px; }
  .study-section-heading p:not(.section-overline) { font-size: 13px; }
  .section-side-note { display: none; }
  .formula-grid, .diagram-grid, .study-grid, .book-question-grid, .source-index { grid-template-columns: 1fr; }
  .formula-grid > :is(article, div, .formula-card) { padding: 23px; }
  .diagram-section { padding-top: 70px; }
  .diagram-grid { gap: 27px; }
  .diagram-canvas { height: 210px; }
  .atlas-section { padding-top: 74px; }
  .study-toolbar { align-items: center; }
  .study-search-label { flex: 1 0 100%; }
  .study-reset { padding-inline: 0 10px; }
  .study-result-count { margin-inline-start: auto; font-size: 12px; }
  .study-grid { gap: 11px; }
  .study-card { padding: 20px; }
  .study-equation, #formula-grid .study-equation { font-size: 21px; }
  #formula-grid .study-card.is-deep-dive { padding: 22px 20px; }
  .criteria-group { padding: 15px 14px 10px; }
  .worked-example { padding: 18px 14px; }
  .example-row { grid-template-columns: 54px minmax(0,1fr); gap: 5px; }
  .study-card .worked-math { font-size: 18px; }
  .challenge-section { margin-top: 70px; padding: 60px 0; }
  .challenge-section .section-link { margin-top: 12px; }
  .book-question-grid { gap: 12px; }
  .sources-section { padding-top: 62px; }
  .study-footer { padding: 25px 20px 35px; flex-wrap: wrap; }
}
@media (max-width: 360px) {
  .study-page .study-main { padding-inline: 16px; }
  .hero-copy h1 { font-size: 42px; }
  .hero-path { gap: 6px; font-size: 10px; }
  .hero-path i { width: 10px; }
  .hero-plate { padding: 18px; min-height: 285px; }
  .plate-equation { font-size: 23px; }
  .plate-equation span { display: block; white-space: nowrap; }
  .study-section-heading h2 { font-size: 28px; }
  .study-result-count { white-space: normal; }
  .study-footer { padding-inline: 16px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto !important; }
  .study-page *, .study-page *::before, .study-page *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; transition-duration: .01ms !important; }
}
@media print {
  .study-page { background: white; color: black; }
  .study-page .topbar, .study-skip, .hero-actions, .hero-path, .study-toolbar, .unit-rail, .study-footer, .section-link { display: none !important; }
  .study-page .study-main { padding: 0; max-width: none; }
  .study-hero { display: block; min-height: 0; padding: 0 0 24px; }
  .hero-plate { display: none; }
  .study-section, .challenge-section { padding: 25px 0; margin: 0; }
  .atlas-workspace { display: block; padding: 0; }
  .formula-grid, .diagram-grid, .study-grid, .book-question-grid, .source-index { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .study-card, .concept-figure, .book-question, .source-index-item, .formula-grid > * { break-inside: avoid; box-shadow: none; }
  .sources-details:not([open]) > *:not(summary) { display: block; }
}