:root {
  color-scheme: light dark;
  --page: #fff;
  --ink: #171717;
  --muted: #4b5563;
  --panel: #f4f6f8;
  --panel-strong: #e6edf4;
  --border: #52606d;
  --link: #0645ad;
  --visited: #5a287d;
  --accent: #7a2e0b;
  --focus: #ffbf47;
  --measure: 74ch;
  --reader-font: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --reader-size: 1.125rem;
  --reader-leading: 1.65;
  --letter-space: normal;
  --word-space: normal;
}

* { box-sizing: border-box; }
html { background: var(--page); color: var(--ink); font-size: 100%; scroll-behavior: smooth; }
body {
  min-inline-size: 0;
  margin: 0;
  overflow-wrap: anywhere;
  background: var(--page);
  color: var(--ink);
  font-family: var(--reader-font);
  font-size: var(--reader-size);
  line-height: var(--reader-leading);
  letter-spacing: var(--letter-space);
  word-spacing: var(--word-space);
}
a { color: var(--link); text-decoration-thickness: .12em; text-underline-offset: .16em; }
a:visited { color: var(--visited); }
a:hover { text-decoration-thickness: .2em; }
:focus-visible { outline: .22rem solid var(--focus); outline-offset: .2rem; border-radius: .12rem; }
.skip-link {
  position: fixed; z-index: 20; inset-block-start: .5rem; inset-inline-start: .5rem;
  padding: .65rem .9rem; transform: translateY(-180%); background: var(--ink); color: var(--page); font-weight: 800;
}
.skip-link:focus { transform: translateY(0); }
.site-header, main, .site-footer { inline-size: min(100% - 2rem, var(--measure)); margin-inline: auto; }
.site-header { padding-block: 2.5rem 1.25rem; border-block-end: .18rem solid var(--border); }
.site-footer { padding-block: 1.5rem 2.5rem; border-block-start: .18rem solid var(--border); color: var(--muted); font-size: .9em; }
main { padding-block: 1.5rem 3rem; }
p, li, dd { max-inline-size: 70ch; }
.eyebrow { margin: 0; color: var(--accent); font-size: .82em; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; }
h1, h2, h3, h4, h5 { line-height: 1.2; text-wrap: balance; }
h1 { margin-block: .2rem .5rem; font-size: clamp(2rem, 7vw, 3.5rem); }
h2 { margin-block-start: 2.4rem; font-size: clamp(1.55rem, 5vw, 2.15rem); }
h3 { margin-block-start: 2rem; font-size: clamp(1.25rem, 4vw, 1.6rem); }
.subtitle { max-inline-size: 58ch; margin-block: .4rem 1rem; color: var(--muted); font-size: 1.08em; }
.view-nav ul, .action-list { display: flex; flex-wrap: wrap; gap: .6rem 1.15rem; margin: 0; padding: 0; list-style: none; }
.view-nav a, .primary-action {
  display: inline-block; min-block-size: 2.75rem; padding: .45rem .75rem; border: .12rem solid var(--border);
  border-radius: .35rem; background: var(--panel); color: var(--ink); font-weight: 750;
}
.view-nav a[aria-current="page"] { border-color: var(--accent); background: var(--accent); color: var(--page); text-decoration: none; }
.reader-intro, .preferences, .chapter-toc, .part-card, .chapter-card, .equation-card,
.semantic-block, .formal-object, .spoken-object, .editorial-note {
  margin-block: 1.5rem; padding: clamp(1rem, 3vw, 1.5rem); border: .12rem solid var(--border);
  border-radius: .45rem; background: var(--panel);
}
.part-card, .semantic-block.definition { border-inline-start: .45rem solid var(--accent); }
.semantic-block.theorem, .semantic-block.lemma, .semantic-block.proposition, .semantic-block.corollary { border-inline-start: .45rem double var(--accent); }
.semantic-block.exercise { border-style: dashed; }
.source-cite { margin-block: .5rem 0; color: var(--muted); font-size: .78em; }
.formula-help { margin-block: .75rem; padding: .55rem .75rem; border: .08rem dashed var(--border); border-radius: .3rem; }
.formula-help summary, .long-description summary { cursor: pointer; font-weight: 750; }
.math-scroll { display: block; max-inline-size: 100%; overflow-x: auto; overflow-y: hidden; }
math { font-size: 1.05em; }
.formal-object { min-inline-size: 0; margin-inline: 0; break-inside: avoid; }
.formal-object figcaption { margin-block-start: 0; font-size: 1.1em; font-weight: 750; }
.object-kind { color: var(--accent); }
.formal-steps { display: grid; gap: 0; margin: 1rem 0; padding: 0; list-style: none; }
.formal-step {
  display: grid; min-inline-size: 0; grid-template-columns: minmax(9rem, 13rem) minmax(0, 1fr);
  gap: .75rem; align-items: baseline; padding: .55rem .25rem; border-block-end: .08rem solid var(--border);
}
.formal-step:last-child { border-block-start: .22rem solid var(--ink); font-weight: 800; }
.step-label { color: var(--muted); font-size: .88em; font-weight: 750; }
.step-content { min-inline-size: 0; max-inline-size: 100%; }
.long-description { margin-block-end: 0; padding-block-start: .8rem; border-block-start: .08rem dashed var(--border); }
.table-wrap { max-inline-size: 100%; overflow-x: auto; }
table { inline-size: 100%; border-collapse: collapse; }
caption { margin-block-end: .5rem; text-align: start; font-weight: 800; }
th, td { padding: .55rem; border: .08rem solid var(--border); text-align: start; vertical-align: top; }
th { background: var(--panel-strong); }
svg, img { max-inline-size: 100%; block-size: auto; }
.preferences-form[hidden] { display: none; }
.preference-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 12rem), 1fr)); gap: 1rem; }
.preference-grid label { display: grid; gap: .3rem; font-weight: 700; }
select, button {
  min-block-size: 2.75rem; max-inline-size: 100%; padding: .45rem .65rem; border: .12rem solid var(--border);
  border-radius: .3rem; background: var(--page); color: var(--ink); font: inherit;
}
button { cursor: pointer; font-weight: 800; }
.preference-actions { margin-block: 1rem 0; }
.status { min-block-size: 1.5em; color: var(--muted); }
kbd, code, .source-code { font-family: ui-monospace, "Cascadia Mono", "Segoe UI Mono", monospace; }
kbd { padding: .08em .3em; border: .08rem solid var(--border); border-radius: .2rem; background: var(--panel-strong); }
.source-lines { margin: 0; padding-inline-start: 4.5rem; }
.source-lines li { max-inline-size: none; padding-inline-start: .6rem; }
.source-lines li:target { background: #fff3a6; color: #171717; outline: .16rem solid #7a2e0b; }
.source-code { display: block; inline-size: 100%; white-space: pre-wrap; overflow-wrap: anywhere; tab-size: 2; }
.sr-only { position: absolute; inline-size: 1px; block-size: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
[data-font="serif"] { --reader-font: Georgia, "Times New Roman", serif; }
[data-font="mono"] { --reader-font: "Cascadia Mono", Consolas, ui-monospace, monospace; }
[data-size="large"] { --reader-size: 1.32rem; }
[data-size="extra-large"] { --reader-size: 1.55rem; }
[data-spacing="generous"] { --reader-leading: 1.85; --letter-space: .035em; --word-space: .12em; }
[data-spacing="extra"] { --reader-leading: 2; --letter-space: .06em; --word-space: .2em; }
[data-theme="dark"] { --page: #111827; --ink: #f9fafb; --muted: #d1d5db; --panel: #1f2937; --panel-strong: #374151; --border: #d1d5db; --link: #93c5fd; --visited: #e9b8ff; --accent: #f0abfc; --focus: #fde047; }
[data-theme="sepia"] { --page: #f6f0df; --ink: #2b2518; --muted: #554c37; --panel: #eee4ca; --panel-strong: #e2d4b4; --border: #655a40; --link: #004c99; --visited: #6b2c70; --accent: #7a2e0b; --focus: #ffbf47; }
[data-theme="contrast"] { --page: #000; --ink: #fff; --muted: #fff; --panel: #000; --panel-strong: #000; --border: #fff; --link: #0ff; --visited: #f9f; --accent: #ff0; --focus: #0f0; }
@media (prefers-color-scheme: dark) {
  body:not([data-theme]), body[data-theme="system"] { --page: #111827; --ink: #f9fafb; --muted: #d1d5db; --panel: #1f2937; --panel-strong: #374151; --border: #d1d5db; --link: #93c5fd; --visited: #e9b8ff; --accent: #f0abfc; --focus: #fde047; }
}
@media (forced-colors: active) { :focus-visible { outline-color: Highlight; } }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
@media (max-width: 34rem) {
  .site-header, main, .site-footer { inline-size: min(100% - 1rem, var(--measure)); }
  .view-nav ul, .action-list { display: grid; grid-template-columns: 1fr; }
  .view-nav a, .primary-action { inline-size: 100%; }
  .formal-step { grid-template-columns: 1fr; gap: .15rem; }
  .source-lines { padding-inline-start: 3.25rem; }
}
@media print {
  :root { color-scheme: light; --page: #fff; --ink: #000; --muted: #333; --panel: #fff; --border: #000; --link: #000; --visited: #000; --accent: #000; }
  body { font-size: 11pt; line-height: 1.45; }
  .site-header, main, .site-footer { inline-size: 100%; max-inline-size: none; }
  .skip-link, .view-nav, .preferences, .status { display: none !important; }
  a { color: inherit; text-decoration: underline; }
}


/* TR-002 Sets reader additions. */
.chapter-section { margin-block: 3rem; }
.chapter-section > h2 { border-block-end: .18rem solid var(--accent); padding-block-end: .35rem; }
.formal-object, .explanation, .digression, .proof { border: .12rem solid var(--border); border-inline-start-width: .45rem; border-radius: .45rem; margin-block: 1.4rem; padding: 1rem 1.2rem; }
.formal-object.definition { border-inline-start-color: #536dfe; }
.formal-object.example { border-inline-start-color: #00897b; }
.formal-object.exercise { border-inline-start-color: #ef6c00; }
.formal-object.theorem, .formal-object.proposition { border-inline-start-color: #8e24aa; }
.explanation { background: color-mix(in srgb, var(--surface) 90%, #b3e5fc); }
.digression { background: color-mix(in srgb, var(--surface) 90%, #fff3e0); }
.proof { border-inline-start-color: #455a64; }
.proof-end { font-style: italic; }
.formula-occurrence { display: inline-block; max-inline-size: 100%; overflow-x: auto; overflow-y: hidden; position: relative; vertical-align: middle; }
.formula-occurrence.display-math { display: block; overflow-x: auto; padding: .65rem .15rem; margin-block: .7rem; }
.formula-core { display: inline; }
.source-pin { font-size: .67em; font-weight: 650; margin-inline-start: .3em; vertical-align: super; white-space: nowrap; }
.source-cite { font-size: .8rem; margin-block-end: 0; text-align: end; }
.reader-correction { display: block; border-inline-start: .25rem solid #c77800; font-size: .86em; margin-block: .55rem; padding: .4rem .65rem; }
.diagram-frame { margin-block: 1rem; }
.set-diagram { display: block; inline-size: min(100%, 36rem); block-size: auto; margin-inline: auto; }
.set-boundary { fill: none; stroke: currentColor; stroke-width: 3; }
.hatch-line { stroke: currentColor; stroke-width: 2; }
.diagram-structure dl { display: grid; grid-template-columns: minmax(7rem, max-content) 1fr; gap: .35rem .8rem; }
.diagram-structure dt { font-weight: 750; }
.diagram-structure dd { margin: 0; }
.equation-grid { display: grid; gap: 1.2rem; }
.equation-card { border: .12rem solid var(--border); border-radius: .5rem; padding: 1rem; min-inline-size: 0; }
.equation-card .math-scroll { overflow-x: auto; }
.occurrence-list { columns: 2 22rem; }
.source-block { margin-block: 2.5rem; }
.source-lines { overflow-x: auto; padding-inline-start: 4.3rem; }
.source-lines li { padding-inline-start: .6rem; white-space: pre; }
.source-lines li:target, :target { outline: .22rem solid #ffbf00; outline-offset: .22rem; }
.shelf-status { font-size: .88em; }
.active-chapter { border-inline-start: .35rem solid var(--accent); padding-inline-start: .75rem; }
.profile-links { display: flex; flex-wrap: wrap; gap: .35rem .8rem; list-style: none; padding: 0; }
@media (max-width: 38rem) {
  .diagram-structure dl { grid-template-columns: 1fr; }
  .occurrence-list { columns: 1; }
  .source-lines { padding-inline-start: 3.2rem; }
  .formal-object, .explanation, .digression, .proof { padding: .8rem; }
}
@media (forced-colors: active) {
  .formal-object, .explanation, .digression, .proof, .equation-card { border-color: CanvasText; }
  .hatch-line, .set-boundary { stroke: CanvasText; }
}


/* Final-static browser accessibility repairs, derived from the silent
   342-document whole-corpus Axe pass. */
.line-number { color: var(--muted) !important; }
.note { color: var(--muted) !important; }
math, math * {
  background-color: var(--page) !important;
  color: var(--ink) !important;
}
pre, table, .explore-card, .formula, .source-generated-math,
.reader-composite-math, .math-scroll, .formula-occurrence, .source-lines {
  max-inline-size: 100% !important;
  overflow-x: auto !important;
}
table { display: block; }
.formula, .source-generated-math, .reader-composite-math {
  display: inline-block;
  vertical-align: middle;
}
.source-lines pre {
  max-inline-size: none !important;
  overflow-x: visible !important;
}
merror, merror mtext {
  background: var(--panel-strong) !important;
  color: var(--ink) !important;
}