:root { color-scheme: light; font-family: "Segoe UI", "Microsoft YaHei", system-ui, sans-serif; color: #203247; background: #fff; letter-spacing: 0; --line: #dce3e8; --muted: #556574; --link: #125bbb; }
* { box-sizing: border-box; }
body { margin: 0; }
a { color: var(--link); text-underline-offset: 3px; }
a:hover { color: #073d80; }
a:focus-visible, summary:focus-visible, [tabindex]:focus-visible { outline: 3px solid #d98918; outline-offset: 4px; }
.shell { width: min(1240px, calc(100% - 64px)); margin-inline: auto; }
.skip-link { position: fixed; left: 16px; top: -70px; z-index: 10; padding: 12px; background: #fff; }
.skip-link:focus { top: 10px; }
.learning-header { border-bottom: 1px solid var(--line); background: #fff; }
.header-inner { min-height: 76px; display: flex; justify-content: space-between; align-items: center; gap: 24px; }
.brand { display: flex; align-items: center; gap: 10px; color: #18344d; text-decoration: none; font-size: 18px; }
.brand img { border-radius: 50%; }
.header-inner nav { display: flex; gap: 26px; align-items: center; font-size: 14px; }
.header-inner nav a { text-decoration: none; }
.language-switch { padding-left: 22px; border-left: 1px solid var(--line); }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; padding-block: 22px; color: var(--muted); font-size: 13px; line-height: 1.6; overflow-wrap: anywhere; }
.breadcrumbs a { text-decoration: none; }
.reading-layout { display: grid; grid-template-columns: 238px minmax(0, 820px); gap: 54px; align-items: start; padding-bottom: 64px; }
.sidebar { position: sticky; top: 20px; max-height: calc(100vh - 40px); overflow-y: auto; padding-right: 14px; border-right: 1px solid var(--line); }
.sidebar nav, .mobile-contents nav { display: grid; gap: 3px; }
.sidebar a, .mobile-contents a { display: block; padding: 8px 10px; color: #485963; font-size: 13px; line-height: 1.65; text-decoration: none; border-left: 3px solid transparent; }
.sidebar a:hover, .mobile-contents a:hover { background: #f1f6f8; }
.sidebar .contents-home, .mobile-contents .contents-home { font-weight: 700; font-size: 15px; margin-bottom: 6px; color: #144b6b; }
.sidebar a[aria-current], .mobile-contents a[aria-current] { border-left-color: #07977f; background: #ecf7f4; color: #08614f; font-weight: 600; }
.sidebar .lesson-link, .mobile-contents .lesson-link { padding-left: 22px; font-size: 12px; }
.nav-section { margin: 22px 10px 5px; color: var(--muted); font-size: 12px; font-weight: 700; }
main { min-width: 0; }
.kicker { font-size: 13px; color: #087c69; font-weight: 700; margin: 4px 0 12px; }
h1 { font-size: 34px; line-height: 1.35; font-weight: 700; margin: 0 0 24px; overflow-wrap: anywhere; }
h2 { font-size: 25px; line-height: 1.45; margin: 44px 0 18px; padding-top: 24px; border-top: 1px solid var(--line); scroll-margin-top: 24px; }
h3 { font-size: 20px; line-height: 1.5; margin: 28px 0 12px; }
p, li { font-size: 16px; line-height: 1.9; }
p { margin: 16px 0; }
li + li { margin-top: 7px; }
ul, ol { padding-left: 25px; }
article { overflow-wrap: anywhere; }
article > p:first-of-type { color: #465c67; font-size: 18px; }
article img { display: block; max-width: 100%; height: auto; margin: 20px auto; }
blockquote { margin: 22px 0; padding: 2px 20px; border-left: 3px solid #0b9781; background: #f1f8f6; }
code { font-size: .9em; background: #f0f3f5; padding: 2px 4px; border-radius: 3px; overflow-wrap: anywhere; }
pre { padding: 18px; background: #f4f6f8; border: 1px solid var(--line); border-radius: 4px; overflow: auto; line-height: 1.65; }
pre code { background: transparent; padding: 0; overflow-wrap: normal; }
.table-scroll { max-width: 100%; overflow-x: auto; margin: 24px 0; border: 1px solid var(--line); border-radius: 4px; }
table { border-collapse: collapse; width: 100%; font-size: 14px; line-height: 1.7; }
th, td { padding: 12px 14px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; min-width: 112px; }
th { background: #eef5f4; color: #25594f; font-weight: 600; }
tr:last-child td { border-bottom: 0; }
tbody tr:nth-child(even) { background: #fafbfc; }
details { border-block: 1px solid var(--line); padding: 12px 0; margin-bottom: 22px; }
summary { cursor: pointer; color: #42545e; font-size: 14px; font-weight: 600; }
.page-contents nav { display: flex; flex-wrap: wrap; gap: 10px 24px; padding: 18px 0 4px; font-size: 14px; }
.mobile-contents { display: none; }
.article-footer { margin-top: 40px; border-top: 1px solid var(--line); padding-top: 24px; display: flex; justify-content: space-between; gap: 20px; font-size: 14px; }
.site-footer { border-top: 1px solid var(--line); padding-block: 30px; display: flex; justify-content: space-between; gap: 16px; color: var(--muted); font-size: 13px; }
@media (max-width: 950px) {
  .reading-layout { grid-template-columns: minmax(0, 1fr); max-width: 820px; }
  .sidebar { display: none; }
  .mobile-contents { display: block; }
}
@media (max-width: 600px) {
  .shell { width: calc(100% - 36px); }
  .header-inner { min-height: 68px; gap: 12px; flex-wrap: wrap; padding-block: 12px; }
  .header-inner nav { gap: 16px; font-size: 13px; }
  .brand { font-size: 16px; }
  .brand img { width: 30px; height: 30px; }
  .language-switch { padding-left: 14px; }
  h1 { font-size: 27px; }
  h2 { font-size: 22px; }
  h3 { font-size: 18px; }
  p, li { font-size: 15px; }
  article > p:first-of-type { font-size: 16px; }
  .breadcrumbs { padding-block: 16px; font-size: 12px; }
  th, td { padding: 10px; min-width: 125px; font-size: 13px; }
  .site-footer { flex-direction: column; }
}
@media print {
  .learning-header, .breadcrumbs, .sidebar, .mobile-contents, .page-contents, .article-footer, .site-footer, .skip-link { display: none; }
  .shell { width: 100%; }
  .reading-layout { display: block; }
  h1 { font-size: 22pt; } h2 { font-size: 17pt; }
  p, li, th, td { font-size: 10pt; }
  table { width: 100%; table-layout: fixed; }
  th, td { min-width: 0; overflow-wrap: anywhere; }
  .table-scroll { overflow: visible; border: 0; }
  tr { break-inside: avoid; }
  pre { white-space: pre-wrap; }
}