:root {
  color-scheme: light;
  --ink: #17313e;
  --muted: #526772;
  --paper: #f5f7f6;
  --panel: #ffffff;
  --line: #d6e1e2;
  --green: #087768;
  --green-dark: #085e53;
  --green-soft: #e9f3ef;
  --amber: #986018;
  --amber-soft: #faf2e3;
  --blue: #14699a;
  --blue-soft: #edf3f8;
  --code: #eef2f3;
  --code-ink: #17313e;
  --shadow: none;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 30px; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font: 16px/1.65 "Segoe UI", Arial, sans-serif;
}
a { color: var(--blue); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--green); }
a:focus-visible, summary:focus-visible, button:focus-visible {
  outline: 3px solid #db9a30;
  outline-offset: 4px;
}
p { margin: 0 0 1em; }
h1, h2, h3 { color: var(--ink); line-height: 1.2; letter-spacing: -0.025em; }
code, pre, .equation { font-family: Consolas, "Liberation Mono", monospace; }
code { padding: 0.08em 0.3em; border-radius: 4px; background: var(--code); font-size: 0.88em; overflow-wrap: anywhere; }
pre {
  margin: 20px 0;
  padding: 18px;
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 7px;
  color: var(--code-ink);
  background: var(--code);
  font-size: 14px;
  line-height: 1.8;
}
pre code { padding: 0; color: inherit; background: transparent; font-size: inherit; overflow-wrap: normal; }
.skip-link { position: absolute; top: -100px; left: 10px; z-index: 10; padding: 12px; background: white; }
.skip-link:focus { top: 10px; }
.mobile-contents-link { display: none; }

/* Compact masthead shared by the handbook and interactive chapters. */
.site-header__inner {
  max-width: 1440px;
  margin: auto;
  padding: 20px 40px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  border-bottom: 1px solid var(--line);
}
.site-brand { display: inline-flex; align-items: center; gap: 12px; color: var(--green); text-decoration: none; font-size: 23px; font-weight: 750; letter-spacing: 0.05em; }
.brand-mark { display: block; width: 42px; height: 42px; padding: 4px; border-radius: 8px; background: var(--ink); object-fit: contain; flex-shrink: 0; print-color-adjust: exact; }
.site-brand__context { margin-left: 3px; color: var(--muted); font-size: 14px; font-weight: 400; letter-spacing: 0; }
.language-switch { display: flex; flex-shrink: 0; align-items: center; gap: 7px; font-size: 14px; }
.language-switch a { display: inline-flex; align-items: center; justify-content: center; min-width: 48px; min-height: 36px; padding: 5px 12px; border: 1px solid var(--line); border-radius: 6px; color: var(--ink); text-decoration: none; }
.language-switch a[aria-current="true"] { background: var(--ink); border-color: var(--ink); color: white; font-weight: 700; }
.language-switch a:hover { border-color: var(--green); }

.layout { max-width: 1440px; margin: auto; display: grid; grid-template-columns: 238px minmax(0, 1fr); gap: 54px; padding: 0 40px; align-items: start; }
.contents { position: sticky; top: 25px; max-height: calc(100vh - 50px); overflow-y: auto; padding: 38px 4px 25px 0; scrollbar-width: thin; font-size: 14px; }
.contents h2 { margin: 24px 0 10px; color: var(--muted); font-size: 11px; font-weight: 700; letter-spacing: 0.13em; text-transform: uppercase; }
.contents ol { margin: 0; padding: 0; list-style: none; }
.contents li { margin: 0; line-height: 1.45; }
.contents a { display: block; padding: 7px 0; color: var(--ink); text-decoration: none; }
.contents a:hover { color: var(--green); }
.contents a[aria-current="page"] { padding-left: 10px; border-left: 3px solid var(--green); color: var(--green); font-weight: 700; }
.contents p { margin: 0; }
.contents .offline-note { border-top: 1px solid var(--line); margin-top: 20px; padding-top: 18px; color: var(--muted); font-size: 12px; }
.chapter { min-width: 0; max-width: 980px; padding: 45px 0 65px; }
.eyebrow, .chapter-number { display: block; margin: 0 0 12px; color: var(--green); font-size: 12px; font-weight: 700; letter-spacing: 0.13em; text-transform: uppercase; }
.chapter h1, .language-entry h1 { margin: 12px 0 18px; font-size: clamp(2rem, 4vw, 3.1rem); }
.chapter h2 { margin: 38px 0 22px; padding-top: 38px; border-top: 1px solid var(--line); font-size: 1.8rem; }
.chapter h3 { margin: 24px 0 14px; font-size: 1.22rem; }
.lead { max-width: 780px; margin: 0 0 22px; color: var(--muted); font-size: 20px; line-height: 1.6; }
.equation { margin: 18px 0; padding: 15px 18px; overflow-x: auto; border: 1px solid var(--line); border-radius: 7px; background: var(--code); font-size: 0.94rem; line-height: 1.85; }
.card-grid, .chapter-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; margin: 20px 0; }
.chapter-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.card { position: relative; padding: 22px; border: 1px solid var(--line); border-radius: 10px; background: white; }
.card h2, .card h3 { margin: 0 0 12px; padding: 0; border: 0; }
.card h3 a { color: var(--ink); text-decoration: none; }
.chapter-grid .card h3 a::after { content: ""; position: absolute; inset: 0; border-radius: 10px; }
.chapter-grid .card:has(a):hover { border-color: var(--green); background: #f1f8f5; }
.chapter-grid .card:focus-within { outline: 3px solid #db9a30; outline-offset: 3px; }
.card p:last-child, .callout p:last-child { margin-bottom: 0; }
.callout { margin: 24px 0; padding: 17px 20px; border-left: 3px solid var(--green); background: var(--green-soft); }
.callout--inspect { border-color: var(--blue); background: var(--blue-soft); }
.callout--warning { border-color: var(--amber); background: var(--amber-soft); }
.callout__title { display: block; margin-bottom: 6px; color: var(--green-dark); font-size: 12px; font-weight: 750; letter-spacing: 0.08em; text-transform: uppercase; }
.callout--inspect .callout__title { color: var(--blue); }
.callout--warning .callout__title { color: var(--amber); }
.table-wrap { margin: 20px 0; overflow-x: auto; border: 1px solid var(--line); border-radius: 8px; }
table { width: 100%; border-collapse: collapse; background: white; font-size: 14px; }
th, td { padding: 12px 15px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { background: #eaf0f1; color: #37515e; font-size: 12px; }
tr:last-child td { border-bottom: 0; }
.model-figure { margin: 24px 0; padding: 14px; overflow-x: auto; border: 1px solid var(--line); border-radius: 10px; background: white; }
.model-figure svg { display: block; width: 100%; min-width: 620px; height: auto; }
.model-figure figcaption { max-width: 76ch; margin: 12px auto 0; color: var(--muted); font-size: 13px; text-align: center; }
.lab-figure img { display: block; width: 100%; min-width: 560px; height: auto; }
.source-list { margin-top: 38px; padding: 22px; border: 1px solid var(--line); border-radius: 8px; background: white; }
.source-list h2 { margin: 0 0 16px; padding: 0; border: 0; font-size: 1.25rem; }
.page-nav { display: flex; justify-content: space-between; gap: 18px; width: min(980px, calc(100% - 412px)); margin: 0 max(40px, calc((100% - 1360px) / 2)) 0 auto; padding-bottom: 40px; }
.page-nav > a, .page-nav > span { display: block; flex: 1 1 0; padding: 16px 20px; border: 1px solid var(--line); border-radius: 8px; background: white; text-decoration: none; }
.page-nav > :last-child { text-align: right; }
.page-nav__label { display: block; margin-bottom: 4px; color: var(--muted); font-size: 11px; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; }
.site-footer__inner { max-width: 1440px; margin: auto; padding: 24px 40px; border-top: 1px solid var(--line); color: var(--muted); font-size: 13px; }
.site-footer p { margin: 0; }
.language-entry { max-width: 980px; margin: 70px auto; padding: 0 40px; }
.language-choice { display: block; padding: 26px; border: 1px solid var(--line); border-radius: 10px; background: white; color: var(--ink); text-decoration: none; }
.language-choice:hover { border-color: var(--green); background: #f1f8f5; }
.language-choice strong { display: block; margin-bottom: 12px; font-size: 1.5rem; }

@media (max-width: 1150px) {
  .layout { grid-template-columns: 210px minmax(0, 1fr); gap: 30px; padding: 0 25px; }
  .site-header__inner, .site-footer__inner { padding-inline: 25px; }
  .chapter-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .page-nav { width: calc(100% - 290px); margin-right: 25px; }
}
@media (max-width: 760px) {
  .site-header__inner { padding: 18px 20px; flex-wrap: wrap; }
  .site-brand__context { display: none; }
  .mobile-contents-link { display: block; width: fit-content; margin: 18px 20px 0; font-size: 14px; }
  .layout { display: flex; flex-direction: column; gap: 0; padding: 0 20px; }
  .chapter { order: -1; width: 100%; padding: 30px 0; }
  .chapter h2 { font-size: 1.5rem; padding-top: 28px; margin-top: 28px; }
  .contents { position: static; width: 100%; max-height: none; padding: 20px 0 30px; border-top: 1px solid var(--line); }
  .lead { font-size: 18px; }
  .page-nav { width: auto; margin: 0 20px; }
  .site-footer__inner { padding: 24px 20px; }
  .language-entry { margin: 35px auto; padding: 0 20px; }
}
@media (max-width: 540px) {
  .card-grid, .chapter-grid { grid-template-columns: 1fr; }
  .chapter, .contents { min-width: 0; overflow-wrap: anywhere; }
  .card { padding: 20px; }
  .page-nav { flex-direction: column; }
  .page-nav > :last-child { text-align: left; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
@media print {
  body { background: white; color: black; font-size: 11pt; }
  .site-header__inner { padding: 0 0 12px; }
  .site-brand__context { display: inline; }
  .layout { display: block; max-width: none; padding: 0; }
  .chapter { max-width: none; padding: 20px 0; }
  .contents, .page-nav, .language-switch, .site-footer, .skip-link, .mobile-contents-link { display: none; }
  a { color: inherit; }
  .chapter h1 { font-size: 30pt; }
  h2, h3 { break-after: avoid; }
  .card, .callout, .model-figure { break-inside: avoid; }
  .chapter-grid, .card-grid { display: block; }
  .card { margin: 12px 0; }
  .table-wrap, .model-figure, pre, .equation { overflow: visible; }
  pre, .equation { white-space: pre-wrap; overflow-wrap: anywhere; }
  .model-figure svg, .lab-figure img { min-width: 0; }
}