/* FahumSci — HTML chapter stylesheet
   Shared by every chapter page and the book index.
   Brand: navy #1b1446 and orange #f05a28 (logo), blue #1e88d0 (book cover). */

:root {
  --navy: #1b1446;
  --navy-2: #2a2266;
  --blue: #1e88d0;
  --blue-d: #14679f;
  --blue-l: #eaf4fc;
  --orange: #f05a28;
  --orange-d: #d4461a;
  --ink: #1f2633;
  --muted: #5b6474;
  --line: #e1e6ee;
  --soft: #f5f8fb;
  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  --display: "Cinzel", "Source Serif 4", Georgia, serif;
  --bar: 66px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--bar) + 24px); -webkit-text-size-adjust: 100%; }
body { margin: 0; background: #fff; color: var(--ink); font: 400 18px/1.72 var(--serif); }
img { max-width: 100%; height: auto; }
a { color: var(--blue-d); text-underline-offset: 2px; }
a:hover { color: var(--orange-d); }
:focus-visible { outline: 3px solid var(--blue); outline-offset: 2px; border-radius: 4px; }
.skip { position: absolute; left: -999px; top: 8px; }
.skip:focus { left: 16px; z-index: 99; background: #fff; padding: 8px 12px; font-family: var(--sans); }
.wrap { max-width: 1240px; margin: 0 auto; padding: 0 24px; }

/* ---------- Top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 50; height: var(--bar); background: rgba(255,255,255,.97); border-bottom: 1px solid var(--line); font-family: var(--sans); }
@supports (backdrop-filter: blur(6px)) { .topbar { background: rgba(255,255,255,.88); backdrop-filter: saturate(1.4) blur(10px); } }
.topbar .wrap { height: 100%; display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; color: var(--navy); }
.brand:hover { color: var(--navy); }
.roundel { width: 46px; height: 46px; overflow: hidden; flex: none; border-radius: 50%; }
.roundel img { width: 46px; max-width: none; display: block; }
.brand-text { display: flex; flex-direction: column; line-height: 1.05; }
.brand-name { font-weight: 800; font-size: 21px; letter-spacing: .01em; color: var(--navy); }
.brand-name span { color: transparent; -webkit-text-stroke: 1.2px var(--navy); }
.brand-tag { font-size: 10.5px; font-weight: 500; letter-spacing: .16em; text-transform: uppercase; color: var(--muted); margin-top: 4px; }
.topnav { display: flex; align-items: center; gap: 4px; }
.topnav > a:not(.btn) { font-size: 14px; font-weight: 500; color: var(--navy); text-decoration: none; padding: 9px 12px; border-radius: 8px; white-space: nowrap; }
@media (max-width: 400px) { .topnav > a:not(.btn) { padding: 8px 6px; font-size: 13px; } .topnav .btn { padding: 10px 12px; } }
.topnav > a:not(.btn):hover { background: var(--soft); }

/* ---------- Buttons & chips ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; font: 600 14px/1 var(--sans); padding: 11px 16px; border-radius: 8px; border: 1px solid transparent; cursor: pointer; text-decoration: none; transition: background-color .15s, color .15s, border-color .15s, box-shadow .15s; white-space: nowrap; }
.btn svg { width: 16px; height: 16px; flex: none; }
.btn-orange { background: var(--orange); color: #fff; }
.btn-orange:hover { background: var(--orange-d); color: #fff; }
.btn-navy { background: var(--navy); color: #fff; }
.btn-navy:hover { background: var(--navy-2); color: #fff; }
.btn-blue { background: var(--blue); color: #fff; }
.btn-blue:hover { background: var(--blue-d); color: #fff; }
.btn-ghost { background: #fff; color: var(--navy); border-color: var(--line); }
.btn-ghost:hover { border-color: var(--blue); color: var(--blue-d); }
.btn.is-done { background: #1f8f50; border-color: #1f8f50; color: #fff; }
.chip { display: inline-flex; align-items: center; gap: 7px; font: 500 13px/1 var(--sans); padding: 8px 12px; border: 1px solid var(--line); border-radius: 999px; color: var(--navy); text-decoration: none; background: #fff; }
.chip svg { width: 14px; height: 14px; color: var(--blue-d); }
a.chip:hover { border-color: var(--blue); color: var(--blue-d); }

/* ---------- Book band ---------- */
.band { position: relative; overflow: hidden; background: linear-gradient(115deg, #1e88d0 0%, #1a78bd 55%, #14679f 100%); color: #fff; font-family: var(--sans); }
.band::before { content: ""; position: absolute; right: -140px; top: -220px; width: 620px; height: 620px; border-radius: 50%; background: rgba(255,255,255,.07); }
.band::after { content: ""; position: absolute; left: -10%; right: -10%; bottom: -46px; height: 70px; border-radius: 50% 50% 0 0; background: rgba(27,20,70,.18); }
.band .wrap { position: relative; z-index: 1; display: flex; align-items: center; gap: 22px; padding-top: 22px; padding-bottom: 24px; }
.band-cover { width: 76px; flex: none; border-radius: 3px; box-shadow: 0 10px 24px rgba(0,0,0,.3); display: block; }
.band-kicker { font-size: 11.5px; font-weight: 600; letter-spacing: .18em; text-transform: uppercase; opacity: .85; }
.band-title { display: block; font: 700 25px/1.15 var(--display); letter-spacing: .035em; margin: 5px 0 7px; color: #fff; text-decoration: none; }
.band-title:hover { color: #fff; text-decoration: underline; text-decoration-thickness: 1px; }
.band-meta { font-size: 13.5px; opacity: .95; }
.band-meta span + span::before { content: "\00B7"; margin: 0 8px; opacity: .7; }

/* ---------- Page layout ---------- */
.layout { display: grid; grid-template-columns: minmax(0, 1fr) 336px; column-gap: 56px; max-width: 1240px; margin: 0 auto; padding: 42px 24px 72px; }
.chapter-head { grid-column: 1; grid-row: 1; min-width: 0; }
.side { grid-column: 2; grid-row: 1 / span 2; }
.chapter-body { grid-column: 1; grid-row: 2; min-width: 0; padding-top: 18px; }
.side-inner { position: sticky; top: calc(var(--bar) + 22px); max-height: calc(100vh - var(--bar) - 44px); overflow-y: auto; display: flex; flex-direction: column; gap: 16px; padding: 2px 2px 6px; scrollbar-width: thin; }

/* ---------- Chapter head ---------- */
.kicker { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 16px; font: 500 13px/1 var(--sans); color: var(--muted); margin-bottom: 20px; }
.chap-no { background: var(--orange); color: #fff; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; padding: 8px 12px; border-radius: 999px; font-size: 11.5px; }
.chapter-head h1 { font: 700 clamp(29px, 3.5vw, 42px)/1.17 var(--serif); color: var(--navy); margin: 0 0 18px; letter-spacing: -.012em; text-wrap: balance; }
.authors { font: 500 16.5px/1.65 var(--sans); color: var(--ink); margin: 0 0 12px; }
.authors sup { font-size: .66em; color: var(--blue-d); font-weight: 700; margin-left: 1px; }
.affil { list-style: none; margin: 0; padding: 0; font: 400 14px/1.55 var(--sans); color: var(--muted); }
.affil li { margin: 3px 0; }
.affil sup { color: var(--blue-d); font-weight: 700; margin-right: 3px; }
.meta-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 20px 0 30px; }
.summary { background: var(--soft); border: 1px solid var(--line); border-left: 4px solid var(--blue); border-radius: 10px; padding: 22px 26px; }
.summary h2 { font: 700 12.5px/1 var(--sans); letter-spacing: .16em; text-transform: uppercase; color: var(--blue-d); margin: 0 0 12px; }
.summary p { margin: 0 0 .7em; font-size: 17px; line-height: 1.7; }
.summary p:last-of-type { margin-bottom: 0; }
.keywords { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; margin-top: 16px; font-family: var(--sans); }
.keywords strong { font-size: 11.5px; letter-spacing: .14em; text-transform: uppercase; color: var(--navy); margin-right: 4px; }
.keywords span { font-size: 13px; line-height: 1.3; background: #fff; border: 1px solid var(--line); border-radius: 999px; padding: 5px 11px; }

/* ---------- Chapter body ---------- */
.prose { max-width: 47em; }
.prose p { margin: 0 0 1.05em; }
.prose h2 { display: flex; align-items: center; gap: 12px; font: 700 15px/1.35 var(--sans); letter-spacing: .1em; text-transform: uppercase; color: var(--navy); margin: 2.4em 0 1em; }
.prose h2::before { content: ""; width: 22px; height: 3px; background: var(--orange); border-radius: 2px; flex: none; }
.prose > h2:first-child { margin-top: .9em; }
.prose h3 { font: 700 21px/1.35 var(--serif); color: var(--navy); margin: 1.8em 0 .55em; }
.prose h4 { font: italic 600 18.5px/1.4 var(--serif); color: var(--navy); margin: 1.5em 0 .45em; }
.prose .dropcap::first-letter { float: left; font: 700 3.5em/.84 var(--serif); color: var(--blue); margin: .07em .09em 0 0; }
.prose ul, .prose ol { margin: 0 0 1.1em; padding-left: 1.4em; }
.prose li { margin: .3em 0; }
.prose li::marker { color: var(--blue-d); }
sup, sub { line-height: 0; }
.figure { margin: 2.1em 0; padding: 18px; border: 1px solid var(--line); border-radius: 12px; background: #fff; box-shadow: 0 1px 2px rgba(16,24,40,.04); }
.figure img { display: block; margin: 0 auto; border-radius: 4px; }
.figure img + img { margin-top: 12px; }
.figure figcaption { font: 400 14.5px/1.55 var(--sans); color: var(--muted); margin: 12px 2px 0; }
.figure figcaption b, .figure figcaption strong { color: var(--navy); }
.figure > figcaption:first-child { margin: 0 2px 12px; }
.figure .figure-note { font: 400 13px/1.5 var(--sans); color: var(--muted); margin: 10px 2px 0; }
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.table-wrap table { width: 100%; border-collapse: collapse; font: 400 14px/1.5 var(--sans); color: var(--ink); }
.table-wrap th, .table-wrap td { padding: 9px 12px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.table-wrap thead th { background: var(--navy); color: #fff; font-weight: 600; border-bottom: 0; }
.table-wrap thead th sup, .table-wrap thead th a { color: #fff; }
.table-wrap tbody tr:nth-child(even) { background: var(--soft); }
.table-wrap td[rowspan] { background: #fff; border-right: 1px solid var(--line); }
.text-box { margin: 1.9em 0; padding: 18px 22px; background: var(--blue-l); border-radius: 10px; font-size: 16.5px; }
.text-box p:last-child { margin-bottom: 0; }
.math { font-family: "Cambria Math", "STIX Two Math", var(--serif); white-space: nowrap; }
.math-block { display: block; text-align: center; margin: .6em 0; white-space: normal; }
.frac { display: inline-flex; flex-direction: column; vertical-align: middle; text-align: center; font-size: .9em; line-height: 1.25; }
.frac > span:first-child { border-bottom: 1px solid currentColor; padding: 0 3px; }

/* ---------- References ---------- */
.references { margin-top: 3em; }
.ref-list { list-style: none; margin: 0; padding: 0; font-size: 15.5px; line-height: 1.6; max-width: 47em; }
.ref-list li { padding: 9px 0 9px 1.7em; text-indent: -1.7em; border-bottom: 1px dashed var(--line); overflow-wrap: anywhere; }
.ref-list li:last-child { border-bottom: 0; }

/* ---------- Previous / next ---------- */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 52px; max-width: 47em; }
.pager a { display: block; padding: 16px 18px; border: 1px solid var(--line); border-radius: 12px; text-decoration: none; color: var(--navy); transition: border-color .15s, box-shadow .15s; }
.pager a:hover { border-color: var(--blue); box-shadow: 0 8px 22px rgba(30,136,208,.12); }
.pager small { display: block; font: 600 11.5px/1 var(--sans); letter-spacing: .14em; text-transform: uppercase; color: var(--muted); margin-bottom: 8px; }
.pager span { font: 600 15.5px/1.4 var(--serif); }
.pager .next { grid-column: 2; text-align: right; }

/* ---------- Sidebar ---------- */
.card { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 18px; font-family: var(--sans); }
.cite-card { border-top: 4px solid var(--orange); box-shadow: 0 12px 32px rgba(27,20,70,.09); }
.card-title { display: flex; align-items: center; gap: 8px; font: 700 12px/1 var(--sans); letter-spacing: .15em; text-transform: uppercase; color: var(--navy); margin: 0 0 12px; }
.card-title svg { width: 16px; height: 16px; color: var(--orange); }
.cite-text { font: 400 14.5px/1.62 var(--serif); color: var(--ink); margin: 0 0 14px; overflow-wrap: anywhere; }
.cite-actions { display: flex; gap: 6px; }
.cite-actions .btn { padding: 9px 11px; font-size: 13px; }
.cite-actions .btn-blue { flex: 1; }
.pdf-btn { width: 100%; padding: 14px 16px; font-size: 14.5px; }
.toc summary { list-style: none; cursor: pointer; margin: 0; }
.toc summary::-webkit-details-marker { display: none; }
.toc summary .chev { margin-left: auto; width: 14px; height: 14px; color: var(--muted); transition: transform .2s; }
.toc[open] summary .chev { transform: rotate(180deg); }
.toc[open] summary { margin-bottom: 10px; }
.toc ol { list-style: none; margin: 0; padding: 0; border-left: 2px solid var(--line); }
.toc a { display: block; padding: 6px 0 6px 14px; margin-left: -2px; border-left: 2px solid transparent; font-size: 13px; line-height: 1.4; color: var(--muted); text-decoration: none; }
.toc a:hover { color: var(--navy); }
.toc a.active { color: var(--blue-d); border-left-color: var(--blue); font-weight: 600; }
.book-card { display: flex; gap: 14px; align-items: center; text-decoration: none; color: var(--ink); }
.book-card:hover { border-color: var(--blue); color: var(--ink); }
.book-card img { width: 64px; border-radius: 3px; box-shadow: 0 4px 12px rgba(0,0,0,.18); flex: none; }
.book-card small { display: block; font-size: 11px; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); }
.book-card b { display: block; font: 700 15px/1.3 var(--serif); color: var(--navy); margin: 4px 0 5px; }
.book-card span { font-size: 13px; color: var(--blue-d); font-weight: 600; }

/* ---------- Book index page ---------- */
.book-hero { display: grid; grid-template-columns: 210px minmax(0,1fr); gap: 40px; align-items: start; max-width: 1240px; margin: 0 auto; padding: 44px 24px 12px; font-family: var(--sans); }
.book-hero img { width: 100%; border-radius: 4px; box-shadow: 0 18px 40px rgba(27,20,70,.22); }
.book-hero h1 { font: 700 clamp(28px, 3.4vw, 40px)/1.15 var(--display); color: var(--navy); letter-spacing: .03em; margin: 6px 0 16px; }
.book-hero dl { display: grid; grid-template-columns: max-content 1fr; gap: 6px 18px; margin: 0 0 22px; font-size: 15px; }
.book-hero dt { color: var(--muted); }
.book-hero dd { margin: 0; color: var(--ink); }
.book-hero .actions { display: flex; flex-wrap: wrap; gap: 8px; }
.contents { max-width: 1240px; margin: 0 auto; padding: 20px 24px 72px; }
.contents h2 { display: flex; align-items: center; gap: 12px; font: 700 15px/1.3 var(--sans); letter-spacing: .1em; text-transform: uppercase; color: var(--navy); margin: 26px 0 8px; }
.contents h2::before { content: ""; width: 22px; height: 3px; background: var(--orange); border-radius: 2px; }
.ch-list { list-style: none; margin: 0; padding: 0; }
.ch-row { display: grid; grid-template-columns: 58px minmax(0,1fr) auto; gap: 18px; padding: 20px 0; border-bottom: 1px solid var(--line); align-items: start; }
.ch-num { font: 700 22px/1.2 var(--sans); color: var(--blue); }
.ch-title { font: 600 19.5px/1.35 var(--serif); color: var(--navy); text-decoration: none; }
.ch-title:hover { color: var(--blue-d); text-decoration: underline; }
.ch-authors { font: 400 14px/1.5 var(--sans); color: var(--muted); margin-top: 5px; }
.ch-meta { font: 500 12.5px/1.4 var(--sans); color: var(--muted); margin-top: 6px; }
.ch-links { display: flex; gap: 6px; }
.ch-links .btn { padding: 8px 11px; font-size: 12.5px; }

/* ---------- Front matter page ---------- */
.editor-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 14px; margin: 0 0 1em; }
.editor-card { display: flex; flex-direction: column; gap: 2px; padding: 16px 18px; border: 1px solid var(--line); border-top: 3px solid var(--blue); border-radius: 10px; background: #fff; font: 400 14px/1.5 var(--sans); color: var(--muted); }
.editor-card b { font: 700 18px/1.3 var(--serif); color: var(--navy); margin-bottom: 4px; }
.editor-card span:first-of-type { color: var(--blue-d); font-weight: 600; }
.fm-card { background: var(--soft); border: 1px solid var(--line); border-radius: 10px; padding: 20px 24px; margin: 0 0 1em; }
.fm-card p { font-size: 16px; }
.fm-card p:last-child { margin-bottom: 0; }
.fm-strong { font: 700 16px/1.4 var(--sans) !important; color: var(--navy); }
.fm-address { font-family: var(--sans); font-size: 14.5px !important; color: var(--muted); }
.spec-list { display: grid; grid-template-columns: max-content minmax(0, 1fr); gap: 0; margin: 0 0 1em; font: 400 15px/1.5 var(--sans); border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.spec-list dt, .spec-list dd { margin: 0; padding: 10px 16px; border-bottom: 1px solid var(--line); }
.spec-list dt { color: var(--muted); background: var(--soft); font-weight: 500; }
.spec-list dd { overflow-wrap: anywhere; }
.spec-list dt:last-of-type, .spec-list dd:last-of-type { border-bottom: 0; }
.preface .closing { font-style: italic; }
.preface .signoff { font: 700 15px/1.4 var(--sans); color: var(--navy); letter-spacing: .04em; }
.fm-contents { max-width: 47em; }
.fm-contents .ch-row { grid-template-columns: 46px minmax(0, 1fr) 48px; padding: 14px 0; }
.fm-contents .ch-num { font-size: 18px; }
.fm-contents .ch-title { font-size: 17.5px; }
.ch-page { font: 600 14px/1.4 var(--sans); color: var(--navy); text-align: right; }
.ch-head { font: 700 11.5px/1 var(--sans) !important; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); padding: 0 0 10px !important; border-bottom: 2px solid var(--navy) !important; }
.ch-head div:last-child { text-align: right; }
@media (max-width: 640px) {
  .spec-list { grid-template-columns: 1fr; }
  .spec-list dt { border-bottom: 0; padding-bottom: 2px; }
  .fm-contents .ch-row { grid-template-columns: 30px minmax(0, 1fr) 36px; gap: 10px; }
}

/* ---------- Footer ---------- */
.footer { background: var(--navy); color: #c9cde2; font: 400 14px/1.6 var(--sans); }
.footer .wrap { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 18px; padding-top: 28px; padding-bottom: 28px; }
.footer .brand, .footer .brand-name { color: #fff; }
.footer .brand-name span { -webkit-text-stroke-color: #fff; }
.footer .brand-tag { color: #aab0cc; }
.footer .roundel { background: #fff; }
.footer a { color: #fff; }
.footer p { margin: 0; }

/* ---------- Responsive ---------- */
@media (max-width: 1020px) {
  .layout { grid-template-columns: minmax(0, 1fr); padding-top: 30px; }
  .chapter-head, .side, .chapter-body { grid-column: 1; grid-row: auto; }
  .side { margin: 22px 0 6px; }
  .side-inner { position: static; max-height: none; overflow: visible; }
  .prose, .ref-list, .pager { max-width: none; }
  .hide-md { display: none !important; }
}
@media (max-width: 640px) {
  :root { --bar: 58px; }
  body { font-size: 17px; }
  .wrap { padding: 0 16px; }
  .layout { padding: 24px 16px 52px; }
  .roundel, .roundel img { width: 38px; height: 38px; }
  .brand-name { font-size: 18px; }
  .brand-tag { display: none; }
  .band .wrap { gap: 14px; padding-top: 16px; padding-bottom: 20px; }
  .band-cover { width: 50px; }
  .band-title { font-size: 17px; }
  .band-meta .opt { display: none; }
  .summary { padding: 18px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { grid-column: 1; }
  .figure { padding: 12px; }
  .book-hero { grid-template-columns: 1fr; gap: 22px; padding-top: 28px; }
  .book-hero img { width: 150px; }
  .ch-row { grid-template-columns: 34px minmax(0,1fr); gap: 12px; }
  .ch-num { font-size: 17px; }
  .ch-links { grid-column: 2; }
}
@media print {
  .topbar, .band, .toc, .book-card, .pdf-btn, .cite-actions, .pager, .footer, .skip { display: none !important; }
  .layout { display: block; padding: 0; }
  .side-inner { position: static; max-height: none; }
  .cite-card { box-shadow: none; margin: 16px 0; }
  body { font-size: 11pt; }
  a { color: inherit; text-decoration: none; }
  .figure, .table-wrap, .ref-list li { break-inside: avoid; }
}