/* Neckpinch — the guidebook: library, book pages and the chapter reader.
   Loaded only on /guide/ pages. Reading settings live on <html> as
   data-r-font, data-r-size, data-r-leading, data-r-width (set before paint). */

/* ── Reading tokens ─────────────────────────────────────────────────── */
:root {
  --r-serif: "Iowan Old Style", "Charter", "Bitstream Charter", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, ui-serif, serif;
  --r-sans: var(--font);
  --r-face: var(--r-serif);
  --r-size: 19px;
  --r-leading: 1.66;
  --r-measure: 38rem;
  --sn-w: 15rem;
  --sn-gap: 2.75rem;
  --c-def: var(--purple);
  --c-thm: var(--accent);
  --c-ex: var(--green);
  --c-warn: var(--orange);
}
:root[data-r-font="sans"] { --r-face: var(--r-sans); }
:root[data-r-size="1"] { --r-size: 16px; }
:root[data-r-size="2"] { --r-size: 17.5px; }
:root[data-r-size="3"] { --r-size: 19px; }
:root[data-r-size="4"] { --r-size: 20.5px; }
:root[data-r-size="5"] { --r-size: 22.5px; }
:root[data-r-leading="tight"] { --r-leading: 1.5; }
:root[data-r-leading="loose"] { --r-leading: 1.82; }
:root[data-r-width="narrow"] { --r-measure: 33rem; }
:root[data-r-width="wide"] { --r-measure: 44rem; }
@media (max-width: 600px) {
  :root[data-r-size="1"] { --r-size: 15px; }
  :root[data-r-size="2"] { --r-size: 16px; }
  :root[data-r-size="3"] { --r-size: 17.5px; }
  :root[data-r-size="4"] { --r-size: 19px; }
  :root[data-r-size="5"] { --r-size: 21px; }
}

/* Sepia: warm paper for long sessions. Declared after the site's themes so it wins. */
:root[data-theme="sepia"] {
  --bg: #f6efe0; --bg-elev: #fbf6ea; --bg-soft: #efe5cf; --bg-sunken: #e7dbc1;
  --text: #3b2f22; --text-2: #6c5a44; --text-3: #8b775e;
  --line: rgba(90, 60, 20, 0.13); --line-strong: rgba(90, 60, 20, 0.22);
  --accent: #9b5a12; --accent-hover: #87500f; --accent-soft: rgba(155, 90, 18, 0.12); --link: #8a4c0b;
  --glass: rgba(246, 239, 224, 0.82);
  --green: #3f7d3a; --orange: #b4531a; --purple: #6f4fb8; --red: #b8323f;
  --shadow-sm: 0 1px 2px rgba(60, 40, 10, 0.06); --shadow: 0 2px 6px rgba(60, 40, 10, 0.06), 0 12px 32px rgba(60, 40, 10, 0.08);
  color-scheme: light;
}
/* Dark, softened for reading: not pure black, not pure white (less glare and halation). */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]):not([data-theme="sepia"]) body.guide { --bg: #121214; --bg-elev: #1b1b1e; --bg-soft: #1f1f23; --text: #e4e4e7; --text-2: #a5a5ab; }
}
:root[data-theme="dark"] body.guide { --bg: #121214; --bg-elev: #1b1b1e; --bg-soft: #1f1f23; --text: #e4e4e7; --text-2: #a5a5ab; }

.guide-preview {
  position: fixed; left: 12px; bottom: 12px; z-index: 60; margin: 0;
  font: 600 12px/1 var(--font); letter-spacing: 0; padding: 8px 12px; border-radius: 999px;
  background: var(--orange); color: #fff; box-shadow: var(--shadow); pointer-events: none;
}
mark.verify { background: rgba(255, 196, 0, 0.32); color: inherit; border-radius: 4px; padding: 0 3px; font-family: var(--mono); font-size: 0.78em; }

/* ── Copyright notices and disclosure (text from Source/guide/notice.json) ── */
.g-notice { margin: 0; font: 12.5px/1.5 var(--font); letter-spacing: 0; color: var(--text-3); }
.g-notice a { color: inherit; text-decoration: underline; text-decoration-color: var(--line-strong); text-underline-offset: 2px; }
.g-notice-top { padding: 14px 0 0; }
.g-notice-bottom { margin: 40px 0 48px; padding-top: 16px; border-top: 1px solid var(--line); }
.r-page .g-notice-top { padding-top: 18px; }
.r-page .g-notice-bottom { margin-top: 0; }
.g-disclosure { font: 13.5px/1.55 var(--font); color: var(--text-2); background: var(--bg-soft); border-radius: 12px; padding: 12px 16px; margin: 0; }
.guide-howto .g-disclosure { margin-top: 1.4em; }

/* ── Library ────────────────────────────────────────────────────────── */
.guide-hero h1 { line-height: 1.02; }
.guide-continue { margin: 28px 0 8px; }
.guide-continue a { display: flex; align-items: center; gap: 16px; padding: 16px 20px; border-radius: 16px; background: var(--bg-elev); border: 1px solid var(--line); box-shadow: var(--shadow-sm); color: var(--text); max-width: 34rem; }
.guide-continue a:hover { text-decoration: none; border-color: var(--line-strong); }
.guide-continue .gc-kicker { display: block; font-size: 13px; color: var(--text-2); }
.guide-continue strong { display: block; font-size: 18px; letter-spacing: -0.02em; }
.guide-continue .gc-ring { flex: none; width: 44px; height: 44px; }
.guide-stats { display: flex; flex-wrap: wrap; gap: 12px 36px; margin: 28px 0 0; }
.guide-stats div { display: flex; flex-direction: column-reverse; }
.guide-stats dt { font-size: 13px; color: var(--text-2); }
.guide-stats dd { margin: 0; font-size: 30px; font-weight: 700; letter-spacing: -0.03em; }

.guide-courses { display: grid; gap: 18px; }
.course { display: grid; grid-template-columns: 88px minmax(0, 1fr); gap: 8px 24px; padding: 32px 0; border-top: 1px solid var(--line); scroll-margin-top: 72px; }
.course-num { font-size: 56px; font-weight: 800; letter-spacing: -0.05em; line-height: 0.9; color: transparent; -webkit-text-stroke: 1.5px var(--text-3); }
.course.is-optional .course-num { -webkit-text-stroke-color: var(--line-strong); }
.course-kicker { font-size: 13px; color: var(--text-2); margin: 0 0 4px; }
.course-kicker a { color: inherit; text-decoration: underline; text-decoration-color: var(--line-strong); text-underline-offset: 3px; }
.course h2 { font-size: clamp(26px, 3.4vw, 34px); margin-bottom: 8px; }
.course-sum { color: var(--text-2); max-width: 44em; margin-bottom: 20px; }
.shelf { display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: 16px; }
.book-cover {
  --cv1: #2d5b8c; --cv2: #1b3a60;
  position: relative; display: flex; flex-direction: column; min-height: 250px; padding: 20px 20px 26px; border-radius: 6px 16px 16px 6px;
  color: #fff; overflow: hidden; isolation: isolate;
  background: linear-gradient(155deg, var(--cv1), var(--cv2));
  box-shadow: inset 6px 0 0 rgba(0, 0, 0, 0.18), var(--shadow);
  transition: transform .25s var(--ease), box-shadow .25s var(--ease);
}
.book-cover::after { content: ""; position: absolute; inset: 0; z-index: -1; background: radial-gradient(120% 80% at 100% 0%, rgba(255, 255, 255, 0.16), transparent 60%); }
.book-cover:hover { text-decoration: none; transform: translateY(-3px); box-shadow: inset 6px 0 0 rgba(0, 0, 0, 0.18), var(--shadow-lg); }
.book-code { font-size: 13px; font-weight: 700; letter-spacing: 0.08em; opacity: 0.85; }
.book-title { margin-top: 14px; font-family: var(--r-serif); font-size: 23px; line-height: 1.15; letter-spacing: -0.01em; font-weight: 600; }
.book-sub { margin-top: 8px; font-size: 14px; line-height: 1.35; opacity: 0.85; }
.book-meta { margin-top: auto; padding-top: 18px; font-size: 12px; opacity: 0.85; }
.book-bar { position: absolute; left: 0; right: 0; bottom: 0; height: 5px; background: rgba(255, 255, 255, 0.18); }
.book-bar i { display: block; height: 100%; width: 0; background: #fff; transition: width .4s var(--ease); }
.guide-howto { margin-top: 72px; }
.guide-howto h2 { font-size: 28px; }

@media (max-width: 640px) {
  .course { grid-template-columns: 1fr; padding: 24px 0; }
  .course-num { font-size: 40px; }
  .shelf { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 12px; }
  .book-cover { min-height: 210px; padding: 16px 16px 22px; }
  .book-title { font-size: 19px; }
}

/* ── Book page ──────────────────────────────────────────────────────── */
.book-hero { padding: clamp(36px, 6vw, 72px) 0 12px; }
.crumbs { display: flex; flex-wrap: wrap; gap: 8px; font-size: 14px; color: var(--text-2); margin-bottom: 28px; }
.crumbs a { color: var(--text-2); }
.book-head { --cv1: #2d5b8c; --cv2: #1b3a60; display: flex; gap: 22px; align-items: center; margin-bottom: 18px; }
.book-spine {
  flex: none; display: grid; place-items: center; width: 76px; height: 104px; border-radius: 4px 12px 12px 4px; color: #fff;
  font-weight: 800; font-size: 22px; letter-spacing: 0.02em;
  background: linear-gradient(155deg, var(--cv1), var(--cv2)); box-shadow: inset 5px 0 0 rgba(0, 0, 0, 0.18), var(--shadow);
}
.book-head .eyebrow { margin-bottom: 4px; }
.book-head h1 { font-family: var(--r-serif); font-weight: 600; font-size: clamp(32px, 5.4vw, 52px); letter-spacing: -0.02em; line-height: 1.05; }
.book-subtitle { margin: 8px 0 0; color: var(--text-2); font-size: 19px; }
.companions { list-style: none; padding: 0; margin: 18px 0 24px; display: grid; gap: 6px; }
.companions li { display: grid; grid-template-columns: 11rem 1fr; gap: 12px; font-size: 15px; }
@media (max-width: 560px) { .companions li { grid-template-columns: 1fr; gap: 0; } .book-spine { width: 58px; height: 80px; font-size: 18px; } }
.toc-head { font-size: 15px; text-transform: uppercase; letter-spacing: 0.06em; color: var(--text-2); margin: 40px 0 8px; }
.book-toc { list-style: none; padding: 0; margin: 0; }
.toc-ch { display: grid; grid-template-columns: 2.6rem minmax(0, 1fr) 1.6rem; gap: 12px; padding: 20px 0; border-top: 1px solid var(--line); scroll-margin-top: 72px; }
.toc-n { font-family: var(--r-serif); font-size: 26px; line-height: 1.1; color: var(--text-3); font-variant-numeric: oldstyle-nums; }
.toc-title { font-family: var(--r-serif); font-size: 22px; font-weight: 600; letter-spacing: -0.01em; color: var(--text); line-height: 1.25; }
a.toc-title:hover { color: var(--link); text-decoration: none; }
.toc-sum { margin: 6px 0 0; color: var(--text-2); font-size: 16px; line-height: 1.45; }
.toc-meta { margin: 8px 0 0; font-size: 13px; color: var(--text-3); }
.toc-ch.is-pending .toc-title { color: var(--text-2); font-weight: 500; }
.toc-state { color: var(--green); opacity: 0; padding-top: 4px; }
.toc-state.is-done { opacity: 1; }
.book-nav { display: flex; justify-content: space-between; gap: 16px; margin-top: 48px; padding-top: 24px; border-top: 1px solid var(--line); }
.book-nav a { display: flex; flex-direction: column; gap: 2px; font-weight: 600; max-width: 48%; }
.book-nav a.next { text-align: right; margin-left: auto; }
.book-nav .muted { font-weight: 400; font-size: 13px; }

/* ── Reader chrome ──────────────────────────────────────────────────── */
body.guide-reader { padding-top: var(--nav-h); }
.rbar {
  position: fixed; inset: 0 0 auto; z-index: 50; height: var(--nav-h);
  background: var(--glass); backdrop-filter: saturate(180%) blur(20px); -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--line); transition: transform .3s var(--ease);
}
.rbar.is-hidden { transform: translateY(-100%); }
.rbar-inner { height: 100%; display: flex; align-items: center; gap: 12px; padding: 0 max(12px, env(safe-area-inset-left)) 0 max(8px, env(safe-area-inset-left)); }
.rbar-back { display: inline-flex; align-items: center; gap: 4px; flex: none; font-size: 14px; font-weight: 600; color: var(--text); padding: 6px 8px; border-radius: 10px; }
.rbar-back:hover { background: var(--bg-soft); text-decoration: none; }
.rbar-title { flex: 1; min-width: 0; margin: 0; text-align: center; font-size: 13px; color: var(--text-2); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; opacity: 0; transition: opacity .25s; }
.rbar-title span { font-weight: 600; color: var(--text); margin-right: 4px; }
.rbar.show-title .rbar-title { opacity: 1; }
.rbar-tools { display: flex; gap: 2px; flex: none; }
.rbar-tools .icon-btn[aria-expanded="true"] { background: var(--bg-soft); color: var(--text); }
.rbar-progress { position: absolute; left: 0; right: 0; bottom: -1px; height: 2px; }
.rbar-progress i { display: block; height: 100%; width: 0; background: var(--accent); transform-origin: left; }

/* ── Reader layout ──────────────────────────────────────────────────── */
.reader { display: grid; grid-template-columns: minmax(0, 1fr); justify-items: center; padding: 0 20px; }
.r-page { width: 100%; max-width: var(--r-measure); min-width: 0; }
.r-rail { display: none; }
@media (min-width: 1240px) {
  .reader { grid-template-columns: minmax(13rem, 1fr) minmax(0, var(--r-measure)) minmax(calc(var(--sn-w) + var(--sn-gap)), 1fr); column-gap: 0; justify-items: stretch; }
  .r-page { grid-column: 2; }
  .r-rail { display: block; grid-column: 1; justify-self: end; width: 14.5rem; margin-right: 3rem; position: sticky; top: calc(var(--nav-h) + 40px); align-self: start; max-height: calc(100vh - var(--nav-h) - 72px); overflow: auto; padding-top: 10.5rem; font-size: 13px; }
  .r-intoc { display: none; }
}
.r-rail-head { margin: 0 0 10px; font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; color: var(--text-3); }
.r-rail ol, .r-intoc ol, .r-drawer-list ol { list-style: none; margin: 0; padding: 0; }
.r-rail li a { display: flex; gap: 8px; padding: 5px 10px; border-left: 2px solid var(--line); color: var(--text-2); line-height: 1.35; }
.r-rail li.lv3 a { padding-left: 22px; font-size: 12.5px; }
.r-rail li a:hover { color: var(--text); text-decoration: none; }
.r-rail li a span, .r-intoc li a span, .r-drawer-list ol a span { color: var(--text-3); font-variant-numeric: tabular-nums; flex: none; }
.r-rail li a.is-active { color: var(--text); border-left-color: var(--accent); font-weight: 600; }

/* ── Chapter head ───────────────────────────────────────────────────── */
.r-head { padding: clamp(32px, 7vw, 80px) 0 8px; }
.r-eyebrow { display: flex; flex-wrap: wrap; gap: 6px; font-size: 13.5px; color: var(--text-2); margin: 0 0 16px; }
.r-eyebrow a { color: var(--text-2); }
.r-head h1 { font-family: var(--r-face); font-weight: 650; font-size: clamp(36px, 6vw, 56px); line-height: 1.04; letter-spacing: -0.025em; text-wrap: balance; }
:root[data-r-font="serif"] .r-head h1 { font-weight: 600; letter-spacing: -0.015em; }
.r-lede { font-family: var(--r-face); font-size: calc(var(--r-size) * 1.18); line-height: 1.45; color: var(--text-2); margin: 18px 0 0; text-wrap: pretty; }
.r-meta { margin: 18px 0 0; font-size: 14px; color: var(--text-3); }
.r-companion { margin: 14px 0 0; padding: 12px 16px; border-radius: 12px; background: var(--bg-soft); font-size: 14.5px; line-height: 1.5; color: var(--text-2); }
.r-intoc { margin-top: 22px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.r-intoc summary { cursor: pointer; padding: 12px 0; font-size: 14px; font-weight: 600; color: var(--text-2); list-style: none; }
.r-intoc summary::-webkit-details-marker { display: none; }
.r-intoc summary::after { content: "＋"; float: right; color: var(--text-3); }
.r-intoc[open] summary::after { content: "－"; }
.r-intoc ol { padding-bottom: 12px; }
.r-intoc li a { display: flex; gap: 10px; padding: 5px 0; color: var(--text); font-size: 15px; }
.r-intoc li.lv3 a { padding-left: 2.2em; font-size: 14px; color: var(--text-2); }

/* ── Chapter body: the reading column ───────────────────────────────── */
.r-body {
  position: relative; margin-top: 36px;
  font-family: var(--r-face); font-size: var(--r-size); line-height: var(--r-leading); letter-spacing: 0;
  hyphens: auto; -webkit-hyphens: auto; hanging-punctuation: first; font-kerning: normal;
  font-variant-numeric: oldstyle-nums proportional-nums;
}
:root[data-r-font="sans"] .r-body { letter-spacing: -0.011em; font-variant-numeric: normal; }
.r-body > * + * { margin-top: 1em; }
.r-body p { margin: 0; text-wrap: pretty; }
.r-body p + p { margin-top: 0.9em; }
.r-body h2, .r-body h3 { font-family: var(--font); letter-spacing: -0.022em; text-wrap: balance; scroll-margin-top: calc(var(--nav-h) + 24px); }
.r-body h2 { font-size: 1.42em; line-height: 1.2; margin-top: 2.6em; }
.r-body h3 { font-size: 1.12em; line-height: 1.3; margin-top: 2em; }
.r-body h2 + *, .r-body h3 + * { margin-top: 0.7em; }
.r-body .anchor { color: inherit; }
.r-body .anchor:hover { text-decoration: none; }
.r-body .secnum { display: inline-block; min-width: 2.4em; color: var(--accent); font-variant-numeric: tabular-nums; font-weight: 600; text-indent: 0; }
.r-body h3 .secnum { min-width: 3.1em; color: var(--text-3); }
/* Hanging numbers: wrapped heading lines align with the text, not the number. */
.r-body h2 { padding-left: 2.4em; text-indent: -2.4em; }
.r-body h3 { padding-left: 3.1em; text-indent: -3.1em; }
@media (min-width: 1240px) {
  .r-body h2, .r-body h3 { position: relative; padding-left: 0; text-indent: 0; }
  .r-body .secnum, .r-body h3 .secnum { position: absolute; right: 100%; margin-right: 0.7em; min-width: 0; text-align: right; }
}
.r-body a { text-decoration: underline; text-decoration-color: color-mix(in srgb, currentColor 35%, transparent); text-underline-offset: 0.18em; text-decoration-thickness: 1px; }
.r-body a:hover { text-decoration-color: currentColor; }
.r-body strong { font-weight: 650; }
.r-body ul, .r-body ol { padding-left: 1.4em; }
.r-body li + li { margin-top: 0.4em; }
.r-body li > p + p { margin-top: 0.5em; }
.r-body blockquote { margin: 1.4em 0; padding: 0 0 0 1.2em; border-left: 3px solid var(--line-strong); color: var(--text-2); font-style: italic; }
.r-body hr { border: 0; text-align: center; margin: 2.6em 0; }
.r-body hr::before { content: "⁂"; color: var(--text-3); letter-spacing: 0.5em; }
.r-body code { font-size: 0.82em; }
.r-body pre { font-size: 0.78em; line-height: 1.55; background: var(--bg-soft); padding: 1em 1.2em; border-radius: 12px; overflow-x: auto; }
.r-body pre code { background: none; padding: 0; }
.r-body table { border-collapse: collapse; width: 100%; font-size: 0.86em; display: block; overflow-x: auto; font-variant-numeric: lining-nums tabular-nums; }
.r-body th, .r-body td { text-align: left; padding: 0.55em 0.8em; border-bottom: 1px solid var(--line); vertical-align: top; }
.r-body th { font-family: var(--font); font-size: 0.9em; color: var(--text-2); }
.r-body .katex { font-size: 1.06em; font-variant-numeric: normal; }
.r-body figcaption, .r-body .sn-body, .r-body .gblock-head { font-variant-numeric: normal; }
.r-body .math-display { margin: 0.85em 0; overflow-x: auto; overflow-y: hidden; padding: 0.15em 0; }
.r-body .math-display > .katex-display, .r-body .katex-display .katex-display { margin: 0; }
.r-body p .katex-display { margin: 0.6em 0; }
.r-body .katex-display > .katex { font-size: 1.1em; }
.r-body .xref em { font-style: normal; }
.r-body .xref-pending { color: var(--text-2); }

/* ── Blocks: definitions, theorems, proofs, examples ────────────────── */
.gblock { margin: 1.6em 0; }
.r-body > .gblock + .gblock { margin-top: 1.2em; }
.gblock-head { font-family: var(--font); font-size: 0.74em; line-height: 1.3; margin-bottom: 0.5em; letter-spacing: 0; }
.gblock-label { font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; }
.gblock-title { font-weight: 600; font-size: 1.12em; text-transform: none; letter-spacing: -0.01em; }
.gblock-title::before { content: "· "; color: var(--text-3); }
.gblock-kind { display: inline-block; font-weight: 600; font-size: 0.92em; padding: 1px 7px; border-radius: 6px; background: var(--bg-sunken); color: var(--text-2); }
.gblock-body > * + * { margin-top: 0.75em; }
.gblock-body > p + p { margin-top: 0.75em; }
.gblock-definition, .gblock-axiom, .gblock-theorem, .gblock-proposition, .gblock-lemma, .gblock-corollary {
  padding: 1em 1.2em 1.1em; border-radius: 4px 14px 14px 4px; background: var(--bg-soft); border-left: 3px solid var(--c-thm);
}
.gblock-definition, .gblock-axiom { border-left-color: var(--c-def); }
.gblock-definition .gblock-label, .gblock-axiom .gblock-label { color: var(--c-def); }
.gblock-theorem .gblock-label, .gblock-proposition .gblock-label, .gblock-lemma .gblock-label, .gblock-corollary .gblock-label { color: var(--c-thm); }
.gblock-proof { margin-top: 0.9em; }
.gblock-proof-label { font-style: italic; font-weight: 600; }
.gblock-proof .gblock-body > :last-child::after { content: "∎"; float: right; margin-left: 1em; color: var(--text-2); }
.gblock-example, .gblock-world { padding: 1em 1.2em 1.1em; border-radius: 14px; border: 1px solid var(--line); }
.gblock-example .gblock-label { color: var(--c-ex); }
.gblock-world { background: linear-gradient(180deg, color-mix(in srgb, var(--c-ex) 6%, transparent), transparent 70%); border-color: color-mix(in srgb, var(--c-ex) 28%, var(--line)); }
.gblock-world .gblock-label { color: var(--c-ex); }
.gblock-exercise { padding: 1em 1.2em 1.1em; border-radius: 14px; border: 1px dashed var(--line-strong); }
.gblock-exercise .gblock-label { color: var(--c-warn); }
.gblock-caveat { padding: 0.9em 1.2em; border-radius: 14px; background: color-mix(in srgb, var(--c-warn) 8%, transparent); }
.gblock-caveat .gblock-label, .gblock-warning .gblock-label { color: var(--c-warn); }
.gblock-warning { padding: 0.9em 1.2em; border-left: 3px solid var(--c-warn); }
.gblock-ahead { padding: 1em 1.2em 1.1em; border-radius: 14px; background: var(--accent-soft); }
.gblock-ahead .gblock-label { color: var(--accent); }
.gblock-recall { padding: 0.9em 1.2em; border-radius: 14px; background: var(--bg-soft); }
.gblock-recall .gblock-label, .gblock-note .gblock-label, .gblock-remark .gblock-label { color: var(--text-2); }
.gblock-history { padding: 1em 1.2em 1.1em; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.gblock-history .gblock-label { color: var(--text-2); }
.gblock-idea { padding: 1em 1.2em; border-radius: 14px; background: color-mix(in srgb, var(--purple) 8%, transparent); }
.gblock-idea .gblock-label { color: var(--purple); }
.gblock-question .gblock-label { color: var(--c-warn); }
details.gblock { margin: 0.9em 0 0; }
details.gblock > summary {
  display: inline-flex; align-items: center; gap: 6px; cursor: pointer; list-style: none; user-select: none;
  font-family: var(--font); font-size: 0.74em; font-weight: 600; padding: 5px 12px; border-radius: 999px; background: var(--bg-sunken); color: var(--text-2);
}
details.gblock > summary::-webkit-details-marker { display: none; }
details.gblock > summary::before { content: "▸"; transition: transform .2s; }
details.gblock[open] > summary::before { transform: rotate(90deg); }
details.gblock > .gblock-body { margin-top: 0.8em; padding-left: 1em; border-left: 2px solid var(--line-strong); }

/* ── Figures ────────────────────────────────────────────────────────── */
.gfig { margin: 2em 0; }
.gfig-art { color: var(--text); display: flex; justify-content: center; }
.gfig-art svg { width: auto; height: auto; max-width: 100%; overflow: visible; }
.gfig figcaption { margin-top: 0.8em; font-family: var(--font); font-size: 0.78em; line-height: 1.5; color: var(--text-2); letter-spacing: -0.005em; }
.gfig-num { font-weight: 700; color: var(--text); }
@media (min-width: 1240px) { .gfig.wide { margin-inline: -4rem; } }
/* Figure vocabulary: SVGs use these classes instead of colours, so they follow the theme. */
.gfig-art text { fill: currentColor; font-family: var(--font); font-size: 13px; letter-spacing: -0.01em; }
.gfig-art .t-sm { font-size: 11.5px; }
@media (max-width: 600px) { .gfig-art text { font-size: 14px; } .gfig-art .t-sm { font-size: 13px; } .gfig-art .t-lg { font-size: 16px; } }
.gfig-art .t-lg { font-size: 15px; font-weight: 600; }
.gfig-art .t-mute { fill: var(--text-2); }
.gfig-art .t-acc { fill: var(--accent); }
.gfig-art .t-warn { fill: var(--orange); }
.gfig-art .t-ok { fill: var(--green); }
.gfig-art .t-def { fill: var(--purple); }
.gfig-art .t-math { font-family: "Times New Roman", "KaTeX_Main", serif; font-style: italic; font-size: 14px; }
.gfig-art .ink { stroke: currentColor; fill: none; }
.gfig-art .ink-f { fill: currentColor; }
.gfig-art .mute { stroke: var(--text-3); fill: none; }
.gfig-art .mute-f { fill: var(--text-3); }
.gfig-art .acc { stroke: var(--accent); fill: none; }
.gfig-art .acc-f { fill: var(--accent); }
.gfig-art .warn { stroke: var(--orange); fill: none; }
.gfig-art .warn-f { fill: var(--orange); }
.gfig-art .ok { stroke: var(--green); fill: none; }
.gfig-art .ok-f { fill: var(--green); }
.gfig-art .def { stroke: var(--purple); fill: none; }
.gfig-art .def-f { fill: var(--purple); }
.gfig-art .soft-f { fill: var(--bg-soft); }
.gfig-art .bg-f { fill: var(--bg); }
.gfig-art .line { stroke: var(--line-strong); fill: none; }

/* ── Sidenotes ──────────────────────────────────────────────────────── */
.sn-ref {
  font: 600 0.62em/1 var(--font); vertical-align: 0.55em; margin: 0 0.1em 0 0.05em; padding: 0.1em 0.3em; border: 0; border-radius: 5px;
  background: var(--accent-soft); color: var(--accent); cursor: pointer;
}
.sn-body { display: none; font-family: var(--font); font-size: 0.8em; line-height: 1.5; color: var(--text-2); letter-spacing: -0.005em; text-align: left; hyphens: manual; }
.sn.open .sn-body { display: block; margin: 0.6em 0 0.4em; padding: 0.7em 0.9em; border-radius: 12px; background: var(--bg-soft); }
.sn-num { font-weight: 700; color: var(--accent); margin-right: 0.2em; }
@media (min-width: 1240px) {
  .sn-ref { pointer-events: none; }
  .sn-body, .sn.open .sn-body {
    display: block; float: right; clear: right; position: relative; width: var(--sn-w); margin: 0.25em calc(-1 * (var(--sn-w) + var(--sn-gap))) 0.9em 0;
    padding: 0; background: none; border-radius: 0; font-size: 13.5px;
  }
  .gblock .sn-body { margin-right: calc(-1 * (var(--sn-w) + var(--sn-gap) + 1.2em)); }
}

/* ── End of chapter ─────────────────────────────────────────────────── */
.r-end { margin: 80px 0 64px; padding-top: 32px; border-top: 1px solid var(--line); display: grid; gap: 20px; }
.r-done { justify-self: start; gap: 8px; }
.r-done[aria-pressed="true"] { background: rgba(29, 157, 82, 0.12); color: var(--green); border-color: transparent; }
.r-next { display: grid; gap: 6px; padding: 22px 24px; border-radius: 18px; background: var(--bg-elev); border: 1px solid var(--line); box-shadow: var(--shadow-sm); color: var(--text); }
a.r-next:hover { text-decoration: none; border-color: var(--line-strong); box-shadow: var(--shadow); }
.r-next-kicker { font-size: 13px; color: var(--accent); font-weight: 600; }
.r-next strong { font-family: var(--r-serif); font-size: 24px; letter-spacing: -0.01em; line-height: 1.2; }
.r-next span:last-child { color: var(--text-2); font-size: 15px; }
.r-next.is-pending .r-next-kicker { color: var(--text-3); }
.r-end-row { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; font-size: 14px; }
.r-end-row a { display: inline-flex; align-items: center; gap: 4px; }
.r-report { font-size: 14px; color: var(--text-2); margin: 0; }

/* ── Drawer (contents) and settings ─────────────────────────────────── */
.r-scrim { position: fixed; inset: 0; z-index: 70; background: rgba(0, 0, 0, 0.28); }
.r-drawer {
  position: fixed; top: 0; right: 0; bottom: 0; z-index: 80; width: min(380px, 92vw); overflow: auto;
  background: var(--bg-elev); border-left: 1px solid var(--line); box-shadow: var(--shadow-lg); padding: 16px 18px 32px;
}
.r-drawer-head { display: flex; align-items: flex-start; gap: 12px; padding: 4px 0 14px; border-bottom: 1px solid var(--line); margin-bottom: 8px; }
.r-drawer-head a { flex: 1; display: flex; flex-direction: column; font-family: var(--r-serif); font-size: 20px; font-weight: 600; color: var(--text); line-height: 1.2; }
.r-drawer-head a .muted { font-family: var(--font); font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; }
.r-drawer-head .icon-btn { font-size: 22px; line-height: 1; }
.r-drawer-list { list-style: none; padding: 0; margin: 0; }
.r-drawer-list > li > a, .r-drawer-list > li > .pending { display: flex; gap: 10px; padding: 9px 8px; border-radius: 10px; color: var(--text); font-size: 15px; line-height: 1.3; }
.r-drawer-list > li > a > span, .r-drawer-list > li > .pending > span { flex: none; width: 1.4em; color: var(--text-3); font-variant-numeric: tabular-nums; }
.r-drawer-list > li > a:hover { background: var(--bg-soft); text-decoration: none; }
.r-drawer-list > li.is-current > a { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.r-drawer-list > li.is-pending .pending { color: var(--text-3); }
.r-drawer-list ol { margin: 4px 0 8px 2.1em; }
.r-drawer-list ol a { display: flex; gap: 8px; padding: 4px 6px; font-size: 13.5px; color: var(--text-2); }
.r-drawer-list ol .lv3 a { padding-left: 1.4em; font-size: 13px; }
.r-drawer-foot { display: block; margin-top: 18px; padding-top: 14px; border-top: 1px solid var(--line); font-size: 14px; }

.r-prefs {
  position: fixed; top: calc(var(--nav-h) + 8px); right: 12px; z-index: 80; width: min(340px, calc(100vw - 24px));
  background: var(--bg-elev); border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow-lg); padding: 14px 16px; font-size: 14px;
}
.r-prefs-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 8px 0; }
.r-prefs-row > span { color: var(--text-2); }
.seg { display: inline-flex; padding: 2px; border-radius: 10px; background: var(--bg-soft); gap: 2px; }
.seg button { border: 0; background: none; color: var(--text); font: 500 13px var(--font); padding: 6px 10px; border-radius: 8px; cursor: pointer; }
.seg button:hover { background: var(--bg-sunken); }
.seg button[aria-pressed="true"] { background: var(--bg-elev); box-shadow: var(--shadow-sm); font-weight: 600; }
.ff-serif { font-family: var(--r-serif); font-size: 15px; }
.r-prefs .link-btn { margin-top: 6px; font-size: 13px; }

/* Resume pill */
.r-resume { position: fixed; left: 50%; bottom: calc(20px + env(safe-area-inset-bottom)); transform: translateX(-50%); z-index: 65; display: flex; align-items: center; gap: 2px; padding: 4px; border-radius: 999px; background: var(--text); box-shadow: var(--shadow-lg); }
.r-resume button { border: 0; background: none; color: var(--bg); font: 600 14px var(--font); padding: 8px 14px; border-radius: 999px; cursor: pointer; white-space: nowrap; }
.r-resume button:hover { background: color-mix(in srgb, var(--bg) 14%, transparent); }
.r-resume .r-resume-x { padding: 8px 12px; font-size: 18px; line-height: 1; }

/* Keep the reading column calm: no reveal animations in chapters. */
@media (prefers-reduced-motion: reduce) { .rbar, .book-cover, .book-bar i { transition: none; } }

/* ── Print: just the text ───────────────────────────────────────────── */
@media print {
  .rbar, .r-rail, .r-drawer, .r-prefs, .r-scrim, .r-end, .r-intoc, .guide-preview, .skip, .sn-ref, .r-resume { display: none !important; }
  body.guide .nav, body.guide .footer, body.guide .guide-continue { display: none !important; }
  .g-notice { display: block !important; color: #444; font-size: 9pt; }
  .g-notice a::after { content: " (" attr(href) ")"; }
  .g-notice-bottom { margin: 24pt 0 0; border-top: 0.5pt solid #999; }
  body.guide-reader { padding: 0; background: #fff; color: #000; }
  .reader { display: block; padding: 0; }
  .r-page { max-width: none; }
  .r-body { font-size: 11pt; line-height: 1.5; }
  .sn-body { display: inline !important; float: none !important; margin: 0 !important; width: auto !important; font-size: 0.85em; }
  .sn-body::before { content: " ["; } .sn-body::after { content: "]"; }
  details.gblock > .gblock-body { display: block; }
  .gblock, .gfig { break-inside: avoid; }
}