:root {
  color-scheme: light;
  --ink: #202e2b;
  --muted: #64716d;
  --line: #dce3df;
  --paper: #fff;
  --green: #087f72;
  --pink: #b04e75;
  --gold: #a76613;
  color: var(--ink);
  background: #f6f8f6;
  font-family: 'Trebuchet MS', sans-serif;
  font-size: 15px;
  letter-spacing: 0;
}
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; display: flex; flex-direction: column; background-image: linear-gradient(180deg, #f1f5f2 0, #f9faf8 440px); }
main { flex: 1; }
a { color: var(--green); text-underline-offset: 4px; }
button, input, select { font: inherit; }
button, select, input[type='range'], input[type='checkbox'] { cursor: pointer; }
button:focus-visible, a:focus-visible, select:focus-visible, input:focus-visible { outline: 3px solid #e2b24f; outline-offset: 3px; }
.site-header, main, .site-footer { width: 100%; margin: auto; }
.site-header { min-height: 42px; display: flex; align-items: center; gap: 16px; padding: 6px 16px; border-bottom: 1px solid #c8d4cd; background: #e9efeb; }
.wordmark { font: bold 19px Georgia, serif; text-decoration: none; color: var(--ink); }
.wordmark-dot { color: var(--green); }
.site-header h1 { font: 600 13px 'Trebuchet MS', sans-serif; margin: 0; padding-left: 16px; border-left: 1px solid #bac9bf; }
.reference-link { margin-left: auto; font-size: 12px; }
.page-navigation { margin-left: auto; display: flex; align-items: center; gap: 18px; font-size: 12px; }
.site-header h1 { min-width: 0; overflow-wrap: anywhere; }
.lesson-title { display: inline-block; margin-left: 16px; color: var(--muted); font-weight: normal; }
.lesson-title:empty { display: none; }
.wordmark, .page-navigation { flex-shrink: 0; }
.book-contents { max-width: 940px; padding: 44px 28px 64px; margin: auto; }
.book-heading { padding-bottom: 34px; }
.book-title { font: normal 42px/1.1 Georgia, serif; margin: 0 0 10px; color: var(--ink); }
.book-subtitle { color: var(--muted); font-size: 13px; margin: 0; }
.contents-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; padding-bottom: 16px; }
.contents-heading h2 { font: normal 23px Georgia, serif; margin: 0; }
.contents-heading > span { color: var(--muted); font-size: 12px; }
.chapter-list { list-style: none; padding: 0; margin: 0; border-bottom: 1px solid var(--line); }
.chapter-list > li { border-top: 1px solid var(--line); }
.chapter-row { display: grid; grid-template-columns: 42px minmax(0, 1fr) 62px; gap: 18px; align-items: baseline; padding: 25px 8px; text-decoration: none; color: var(--ink); }
.chapter-number { color: var(--muted); font: 15px Georgia, serif; font-variant-numeric: tabular-nums; }
.chapter-description { min-width: 0; }
.chapter-description h3 { font: normal 24px/1.25 Georgia, serif; margin: 0 0 8px; overflow-wrap: anywhere; }
.chapter-description p { font-size: 13px; color: var(--muted); line-height: 1.7; margin: 0; max-width: 65ch; }
.chapter-status { color: var(--muted); font-size: 11px; text-align: right; }
.chapter-status svg { display: block; margin-left: auto; color: var(--green); }
.chapter-link h3 { color: var(--green); }
.chapter-link:hover { background: #eaf2ed; }
.chapter-link:hover h3 { text-decoration: underline; text-underline-offset: 5px; }
.chapter-pagination { display: flex; justify-content: space-between; gap: 24px; padding: 16px 20px; border-top: 1px solid var(--line); font-size: 12px; }
.chapter-pagination a { display: inline-flex; align-items: center; gap: 8px; min-width: 0; }
.chapter-pagination svg { flex-shrink: 0; }
.sect1 { border-top: 1px solid var(--line); margin-top: 0; padding: 18px 20px; }
.sect1 > h2 { font: 600 15px 'Trebuchet MS', sans-serif; margin: 0 0 16px; }
.sect1 > .sectionbody { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.sect2 h3 { margin: 0 0 10px; font-size: 13px; }
.sect2 p { color: var(--muted); font-size: 12px; line-height: 1.8; margin: 0; }
.site-footer { display: flex; justify-content: space-between; gap: 16px; padding: 8px 16px; border-top: 1px solid var(--line); font-size: 10px; color: var(--muted); }
@media (max-width: 640px) {
  .book-contents { padding: 28px 18px 42px; }
  .book-heading { padding-bottom: 28px; }
  .book-title { font-size: 36px; }
  .chapter-row { grid-template-columns: 26px minmax(0, 1fr); gap: 8px 12px; padding: 20px 0; }
  .chapter-description h3 { font-size: 21px; }
  .chapter-status { grid-column: 2; text-align: left; }
  .chapter-status svg { margin: 0; }
  .page-navigation { gap: 12px; }
  .site-header { padding-inline: 10px; gap: 10px; }
  .site-header h1 { padding-left: 10px; }
  .lesson-title { display: block; margin-left: 0; margin-top: 3px; }
  .wordmark { font-size: 17px; }
  .sect1 > .sectionbody { grid-template-columns: 1fr; gap: 16px; }
  .site-footer { font-size: 10px; }
}