:root {
  color-scheme: light;
  --ink: #20252e;
  --muted: #505966;
  --paper: #ffffff;
  --ground: #f3f4f6;
  --line: #c5cbd3;
  --blue: #1255ad;
  --berry: #990454;
  --blue-wash: #eaf1fb;
  --berry-wash: #f8eaf1;
  --dock-space: 6.5rem;
  font-family: "Segoe UI", "Gill Sans", "Trebuchet MS", ui-sans-serif, system-ui, sans-serif;
  font-size: 18px;
  color: var(--ink);
  background: var(--ground);
}

* { box-sizing: border-box; }
html { scroll-padding-block: 1.5rem 7rem; }
body { margin: 0; padding-block-end: calc(var(--dock-space) + env(safe-area-inset-bottom)); line-height: 1.6; }
main { margin: 0 auto; max-inline-size: 1220px; padding: 3.5rem 2.5rem 0; }
main:focus { outline: none; }
article { min-inline-size: 0; }
section { margin-block: 0 2.7rem; }
h1, h2, h3, p, ul, figure { margin-block-start: 0; }
h1 { font-size: clamp(2rem, 4.4vw, 3.9rem); line-height: 1.09; letter-spacing: -.038em; font-weight: 650; margin-block-end: 1.4rem; overflow-wrap: break-word; }
h2 { font-size: 1.5rem; line-height: 1.24; font-weight: 650; letter-spacing: -.018em; margin-block-end: 1rem; }
h3 { font-size: 1.2rem; line-height: 1.3; }
p { margin-block-end: 1rem; }
ul { padding-inline-start: 1.35rem; margin-block-end: 1.4rem; }
li { padding-inline-start: .15rem; margin-block-end: .55rem; }
strong { font-weight: 650; }
a { display: inline-flex; align-items: center; min-inline-size: 44px; min-block-size: 44px; padding: .45rem .15rem; color: var(--blue); text-underline-offset: .2em; text-decoration-thickness: 1px; overflow-wrap: anywhere; }
a:hover { text-decoration-thickness: 2px; }
button, summary { font: inherit; font-size: 1rem; min-inline-size: 44px; min-block-size: 48px; cursor: pointer; }
button { color: var(--ink); background: var(--paper); border: 1px solid var(--muted); padding: .55rem .85rem; border-radius: 3px; }
button:hover { background: var(--blue-wash); }
:focus-visible { outline: 3px solid var(--berry); outline-offset: 4px; }
table { inline-size: 100%; border-collapse: collapse; font-size: 1rem; line-height: 1.5; }
caption { text-align: start; padding-block: 0 .9rem; color: var(--muted); font-size: 1rem; }
th, td { vertical-align: top; text-align: start; padding: 1rem .9rem; border-block-end: 1px solid var(--line); }
thead { background: var(--ink); color: var(--paper); }
tbody th { inline-size: 34%; background: var(--blue-wash); font-weight: 600; }
tbody td { background: var(--paper); }
summary { padding: .65rem .85rem; }
summary::marker { color: var(--blue); }
dialog { color: var(--ink); background: var(--paper); }

/* Small layout utilities sit beside the semantic base. */
.measure { max-inline-size: 68ch; }
.cluster { display: flex; flex-wrap: wrap; gap: .35rem 1.1rem; }
.stack > * + * { margin-block-start: 1rem; }

.skip-link { position: fixed; z-index: 20; inset-block-start: .6rem; inset-inline-start: .8rem; padding: .6rem 1rem; background: var(--paper); transform: translateY(-180%); border: 2px solid var(--berry); }
.skip-link:focus { transform: translateY(0); }
.masthead { background: var(--ink); color: var(--paper); }
.masthead-inner { max-inline-size: 1220px; min-block-size: 82px; padding: .7rem 2.5rem; margin: auto; display: flex; align-items: center; justify-content: space-between; gap: 1.5rem; }
.masthead p { margin: 0; font-size: 1rem; }
.word-label { color: var(--paper); text-decoration: none; font-size: 1.25rem; font-weight: 650; letter-spacing: -.02em; }
.word-label::before { content: ""; inline-size: 15px; block-size: 22px; border-inline-start: 4px solid #77b0ff; border-block: 2px solid #77b0ff; margin-inline-end: .65rem; }
.masthead :focus-visible, .bottom-dock :focus-visible { outline-color: #ffffff; }

.chapter-intro { display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr); gap: 3.5rem; align-items: end; border-block-end: 1px solid var(--line); padding-block-end: 2.75rem; margin-block-end: 3rem; }
.chapter-intro.intro-text { grid-template-columns: minmax(0, 68ch); }
.chapter-body > .check-diagram { margin-block-end: 2.7rem; }
.shelf-label { color: var(--blue); font-size: 1rem; font-weight: 600; padding-inline-start: .8rem; border-inline-start: 3px solid var(--berry); margin-block-end: 1.5rem; }
.opener { color: var(--berry); font-size: 1.1rem; font-weight: 600; margin-block-end: .6rem; }
.lead { max-inline-size: 55ch; font-size: 1.13rem; margin-block-end: 0; }
.chapter-body { max-inline-size: 68ch; margin-inline: auto; }
.opening .chapter-intro { grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr); }
.opening .chapter-body { max-inline-size: 76ch; }
.opening .chapter-body > section { max-inline-size: 68ch; }

.check-diagram { margin: 0; padding: 1.15rem; background: var(--paper); border-block-start: 5px solid var(--blue); box-shadow: 0 1px 0 var(--line); }
.check-diagram ul { list-style: none; margin: 0; padding: 0; }
.check-diagram li { position: relative; margin: 0; padding: .75rem 0 .85rem 1.2rem; border-inline-start: 2px solid var(--line); }
.check-diagram li::before { content: ""; position: absolute; inset-inline-start: -7px; inset-block-start: 1.25rem; inline-size: 12px; block-size: 12px; background: var(--blue); border: 2px solid var(--paper); }
.check-diagram li:last-child { border-color: transparent; }
.check-diagram li:last-child::before { background: var(--berry); }
.check-diagram strong { display: block; font-size: 1.06rem; }
.check-diagram span { display: block; color: var(--muted); font-size: 1rem; }
.check-diagram figcaption { border-block-start: 1px solid var(--line); margin-block-start: .3rem; padding-block-start: .8rem; color: var(--muted); font-size: 1rem; line-height: 1.45; }
.diagram-review, .diagram-cost, .diagram-cautions { border-block-start-color: var(--berry); }

.chapter-tiles { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-block: 0 3rem; }
.tile { position: relative; display: flex; flex-direction: column; align-items: start; justify-content: space-between; padding: 1.35rem 2.75rem 1.35rem 1.35rem; min-block-size: 182px; text-decoration: none; }
.tile > span:first-child { font-size: 1rem; }
.tile strong { margin-block-start: 1rem; font-size: 1.42rem; line-height: 1.22; }
.tile > span:last-child { position: absolute; inset-block-end: 1.2rem; inset-inline-end: 1.1rem; font-size: 1.45rem; }
.tile-blue { background: var(--blue); color: var(--paper); }
.tile-berry { background: var(--berry); color: var(--paper); }
.tile-light { background: var(--paper); color: var(--ink); border: 1px solid var(--line); }
.tile:hover strong { text-decoration: underline; text-underline-offset: .15em; }
.tile-blue:focus-visible, .tile-berry:focus-visible { outline-color: var(--ink); }

.evidence { margin-block: 1.15rem 0; border-block: 1px solid var(--line); background: var(--paper); }
.evidence summary { color: var(--blue); font-weight: 600; padding-inline: .8rem; }
.evidence summary:hover { background: var(--blue-wash); }
.evidence-body { padding: .6rem 1rem 1rem; font-size: 1rem; }
.source-links { display: flex; flex-direction: column; gap: .45rem; }
.source-link { min-block-size: 48px; padding: .5rem .1rem; line-height: 1.45; }
.source-link::after { content: "↗"; margin-inline-start: .6rem; }
.evidence-drawer { position: fixed; inset: 0 0 0 auto; margin: 0; block-size: 100dvh; max-block-size: 100dvh; inline-size: min(100%, 570px); max-inline-size: 100%; border: 0; border-inline-start: 5px solid var(--blue); padding: 0; }
.evidence-drawer[open] { display: flex; flex-direction: column; }
.evidence-drawer::backdrop { background: #20252eb3; }
.drawer-top { display: flex; justify-content: flex-end; padding: 1rem 1.35rem .5rem; }
.drawer-top form { margin: 0; }
.evidence-drawer h2 { margin: .8rem 1.5rem 1.4rem; padding-block-end: 1rem; border-block-end: 1px solid var(--line); }
.drawer-content { overflow-y: auto; padding: 0 1.5rem 2rem; }
.drawer-content .evidence-body { padding: 0; }

.worksheet { background: var(--paper); border-block-start: 3px solid var(--ink); padding: 1.4rem 1.35rem .7rem; }
.write-lines { list-style: none; padding: 0; margin: 0; }
.write-lines li { padding: 0; margin-block-end: 1.2rem; }
.writing-space { display: block; block-size: 1.1rem; margin-block-start: .45rem; border-block-end: 1px solid #9da6b3; }
.recap { margin-block: 3rem 0; border-inline-start: 5px solid var(--berry); padding: .4rem 1.3rem .1rem; }
.recap h2 { color: var(--berry); font-size: 1.18rem; margin-block-end: .7rem; }
.recap ul { margin-block-end: .7rem; }
.chapter-end { margin-block: 1.5rem 3.5rem; }
.next-link { background: var(--blue); color: var(--paper); padding: .8rem 1.15rem; min-block-size: 54px; text-decoration: none; font-weight: 600; }
.next-link:hover { text-decoration: underline; }
.action-links { display: flex; flex-wrap: wrap; gap: .6rem 1rem; margin-block: 1rem 1.5rem; }
.action-link { border-block-end: 2px solid var(--blue); text-decoration: none; min-block-size: 50px; }
.action-link:hover { background: var(--blue-wash); }
.table-wrap { inline-size: 100%; }
.urgent-box { border-inline-start: 5px solid var(--berry); background: var(--berry-wash); padding: 1.4rem 1.25rem; }
.urgent-box .evidence { background: transparent; }
.urgent-line { font-size: 1.3rem; line-height: 1.4; font-weight: 650; color: #71023e; padding-block: .7rem; }

footer { border-block-start: 1px solid var(--line); background: #e7eaf0; }
.footer-inner { max-inline-size: 1220px; margin: auto; padding: 1.6rem 2.5rem 1.5rem; }
footer p { max-inline-size: 70ch; font-size: 1rem; line-height: 1.5; }
.footer-links { display: flex; flex-wrap: wrap; gap: .25rem 1.4rem; }
.footer-links a { min-block-size: 48px; font-size: 1rem; padding-block: .6rem; }

.bottom-dock { position: fixed; z-index: 10; inset: auto 0 0; background: var(--ink); color: var(--paper); padding-block-end: env(safe-area-inset-bottom); box-shadow: 0 -1px 0 #ffffff33; }
.dock-inner { max-inline-size: 960px; margin: auto; display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); }
.dock-inner > a, .chapter-menu > summary { min-block-size: 74px; display: flex; align-items: center; justify-content: center; color: var(--paper); font-size: 1rem; text-decoration: none; padding: .7rem .3rem; text-align: center; border-inline-end: 1px solid #ffffff24; }
.dock-inner > a[aria-current="page"] { background: var(--blue); box-shadow: inset 0 4px 0 #c7dfff; }
.dock-inner > a:hover, .chapter-menu > summary:hover { background: #353e4c; }
.chapter-menu > summary { list-style: none; border: 0; }
.chapter-menu > summary::-webkit-details-marker { display: none; }
.chapter-menu[open] > summary { background: var(--berry); }
.chapter-menu-panel { position: fixed; inset-inline: max(1rem, calc((100vw - 930px) / 2)); inset-block-end: calc(74px + env(safe-area-inset-bottom)); max-block-size: min(68vh, 620px); overflow-y: auto; background: var(--paper); color: var(--ink); border: 1px solid var(--line); border-block-end: 4px solid var(--berry); padding: 1rem; box-shadow: 0 -10px 35px #20252e26; display: none; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: .2rem 1rem; }
.chapter-menu[open] > .chapter-menu-panel { display: grid; }
.chapter-menu-panel p { grid-column: 1 / -1; margin: 0 0 .4rem; font-weight: 650; }
.chapter-menu-panel a { min-block-size: 48px; padding: .6rem .5rem; }
.chapter-menu-panel a[aria-current="page"] { color: var(--berry); font-weight: 650; }
.chapter-menu-panel :focus-visible { outline-color: var(--berry); outline-offset: -1px; }

@media (max-width: 760px) {
  main { padding: 2rem 1.15rem 0; }
  .masthead-inner { min-block-size: 78px; padding: .6rem 1.15rem; gap: .5rem; flex-wrap: wrap; }
  .masthead p { font-size: 1rem; }
  .chapter-intro, .opening .chapter-intro { grid-template-columns: minmax(0, 1fr); gap: 1.8rem; padding-block-end: 2rem; margin-block-end: 2rem; }
  h1 { font-size: clamp(2.15rem, 8vw, 3.2rem); }
  .lead { font-size: 1.1rem; }
  .check-diagram { padding: .9rem 1rem; }
  .check-diagram li { padding-block: .6rem; }
  .check-diagram li::before { inset-block-start: 1.1rem; }
  .check-diagram figcaption { font-size: 1rem; }
  .chapter-tiles { gap: 10px; }
  .tile { min-block-size: 185px; padding: 1rem 1rem 2.8rem; }
  .tile strong { font-size: 1.16rem; }
  .tile > span:first-child { font-size: 1rem; line-height: 1.4; }
  .tile > span:last-child { inset-block-end: .65rem; }
  .worksheet, .urgent-box { padding: 1.15rem 1rem .5rem; }
  .footer-inner { padding: 1.4rem 1.15rem; }
  .footer-links { display: flex; flex-direction: column; align-items: start; gap: .1rem; }
  th, td { padding: .8rem .6rem; overflow-wrap: break-word; }
  .dock-inner > a, .chapter-menu > summary { font-size: 16px; min-block-size: 74px; }
  .chapter-menu-panel { grid-template-columns: minmax(0, 1fr); max-block-size: 58vh; }
  .evidence-drawer { border-inline-start-width: 3px; }
  .evidence-drawer h2 { margin-inline: 1.15rem; }
  .drawer-content { padding-inline: 1.15rem; }
}

@media (max-width: 350px) {
  .chapter-tiles { grid-template-columns: minmax(0, 1fr); }
  .dock-inner { grid-template-columns: repeat(5, minmax(0, 1fr)); }
  .dock-inner > a, .chapter-menu > summary { overflow-wrap: anywhere; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

@media print {
  :root { font-size: 16px; background: white; }
  body { background: white; padding: 0; }
  .bottom-dock, .skip-link, .chapter-end, .footer-links, .evidence-drawer { display: none !important; }
  .masthead { background: white; color: var(--ink); border-block-end: 1px solid var(--ink); }
  .word-label { color: var(--ink); }
  .word-label::before { border-color: var(--ink); }
  .masthead-inner, main, .footer-inner { padding-inline: 0; }
  main { padding-block-start: 1.5rem; }
  .chapter-intro, .opening .chapter-intro { grid-template-columns: 1fr; padding-block-end: 1rem; margin-block-end: 1.5rem; }
  h1 { font-size: 2rem; }
  .check-diagram { display: none; }
  .chapter-body, .opening .chapter-body { max-inline-size: none; }
  .worksheet { border: 1px solid var(--ink); break-inside: avoid; }
  .writing-space { block-size: 2rem; }
  details::details-content { content-visibility: visible; display: block; }
  details > :not(summary) { display: block !important; }
  .evidence { break-inside: avoid; }
  .recap, .urgent-box { break-inside: avoid; }
  footer { background: white; }
  a { color: var(--ink); }
}