:root {
  color-scheme: light;
  --bg: #ffffff;
  --surface: #ffffff;
  --surface-muted: #f8fafc;
  --surface-callout: #f1f5f9;
  --text: #172033;
  --heading: #101827;
  --muted: #536176;
  --link: #1f5fbf;
  --link-hover: #174a94;
  --accent: #2563eb;
  --border: #d8e0eb;
  --focus: #93c5fd;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
}
a { color: var(--link); text-underline-offset: .16em; }
a:hover { color: var(--link-hover); }
a:focus, button:focus, input:focus { outline: 3px solid var(--focus); outline-offset: 2px; }
img { max-width: 100%; height: auto; }
.skip-link { position: absolute; left: -999px; top: 1rem; z-index: 10; padding: .65rem .9rem; background: var(--surface); border: 1px solid var(--border); }
.skip-link:focus { left: 1rem; }

.site-header { position: sticky; top: 0; z-index: 5; border-bottom: 1px solid var(--border); background: rgb(255 255 255 / 96%); }
.site-nav { display: flex; align-items: center; justify-content: space-between; gap: 1.25rem; width: min(1180px, calc(100% - 2rem)); margin: 0 auto; padding: .85rem 0; }
.brand { display: inline-flex; align-items: center; gap: .65rem; color: var(--heading); font-weight: 750; text-decoration: none; }
.brand-mark { display: inline-grid; place-items: center; width: 1.85rem; height: 1.85rem; border: 1px solid #b9c8dc; border-radius: .35rem; background: #f8fafc; color: #274060; font-size: .72rem; letter-spacing: .04em; }
.site-menu { display: flex; align-items: center; gap: 1rem; }
.site-menu a { color: #40506a; text-decoration: none; font-weight: 650; }
.site-menu a:hover { color: var(--link); text-decoration: underline; }
.nav-toggle { display: none; }

.layout-shell { display: grid; grid-template-columns: 16rem minmax(0, 52rem); justify-content: center; gap: 2rem; width: min(1180px, calc(100% - 2rem)); margin: 0 auto; padding: 1.5rem 0 4rem; }
.site-sidebar { position: sticky; top: 5rem; align-self: start; max-height: calc(100vh - 6rem); overflow: auto; padding: .25rem 1rem .5rem 0; border-right: 1px solid var(--border); }
.search-label { display: block; margin-bottom: .35rem; color: var(--heading); font-size: .86rem; font-weight: 700; }
.site-search { width: 100%; min-height: 2.45rem; margin-bottom: .35rem; padding: .55rem .7rem; border: 1px solid var(--border); border-radius: .35rem; background: var(--surface); color: var(--text); font: inherit; }
.search-status { margin: 0 0 .85rem; color: var(--muted); font-size: .78rem; line-height: 1.4; }
.doc-tree { display: grid; gap: .05rem; }
.doc-tree a { display: block; padding: .36rem .25rem; border-radius: .25rem; color: #43536d; text-decoration: none; font-size: .94rem; }
.doc-tree a:hover { color: var(--link); background: var(--surface-muted); }
.content { min-width: 0; }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: .45rem; margin: .25rem 0 1.1rem; color: var(--muted); font-size: .92rem; }
.breadcrumbs a { color: var(--muted); }

.article { max-width: 100%; padding: .25rem 0 2rem; background: var(--surface); }
.article-meta { display: flex; flex-wrap: wrap; gap: .45rem; margin-bottom: 1rem; color: var(--muted); font-size: .9rem; }
.article-meta span { padding: .15rem .5rem; border: 1px solid var(--border); border-radius: .3rem; background: var(--surface-muted); }
.article-grid { display: grid; grid-template-columns: minmax(0, 1fr) 14rem; gap: 2.25rem; align-items: start; }
.article-body :is(h1, h2, h3) { color: var(--heading); line-height: 1.25; letter-spacing: -.01em; }
.article-body h1 { margin: .25rem 0 1rem; font-size: clamp(2rem, 4vw, 2.65rem); }
.article-body h2 { margin: 2.1rem 0 .75rem; font-size: clamp(1.35rem, 2.5vw, 1.65rem); }
.article-body h3 { margin-top: 1.5rem; font-size: 1.15rem; }
.article-body p, .article-body li { font-size: 1rem; }
.article-body table { display: block; max-width: 100%; overflow-x: auto; border-collapse: collapse; }
.article-body th, .article-body td { padding: .6rem; border: 1px solid var(--border); vertical-align: top; }
.article-body blockquote, .journey-callout, .read-next, .use-with, .practical-example, .checklist-card, .related-guide { margin: 1rem 0; padding: .85rem 1rem; border-left: 3px solid var(--accent); background: var(--surface-callout); }

.desktop-toc { position: sticky; top: 5rem; padding: .75rem 0 0 1rem; border-left: 1px solid var(--border); color: var(--muted); font-size: .88rem; }
.desktop-toc ul { padding-left: 1rem; margin-top: .35rem; }
.desktop-toc a { color: var(--muted); text-decoration: none; }
.desktop-toc a:hover { color: var(--link); text-decoration: underline; }
.toc-title { margin: 0 0 .35rem; color: var(--heading); font-weight: 750; }
.mobile-toc { display: none; margin: 1rem 0; }
.mobile-toc button { width: 100%; min-height: 2.5rem; border: 1px solid var(--border); border-radius: .35rem; background: var(--surface-muted); color: var(--heading); font: inherit; font-weight: 700; text-align: left; padding: .55rem .75rem; }
.toc-panel { display: none; padding: .75rem 1rem; border: 1px solid var(--border); border-top: 0; }
.mobile-toc.is-open .toc-panel { display: block; }

.card-grid, .cta-grid, .checklist-grid, .learning-path-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); gap: .85rem; margin: 1rem 0 1.6rem; }
.journey-card, .cta-card, .topic-card, .checklist-card { display: grid; gap: .45rem; padding: .95rem 1rem; border: 1px solid var(--border); border-radius: .4rem; background: var(--surface); color: var(--text); text-decoration: none; }
.journey-card:hover, .cta-card:hover, .topic-card:hover { border-color: #9fb1c7; background: var(--surface-muted); }
.journey-card strong, .cta-card strong, .topic-card strong, .checklist-card strong { color: var(--heading); font-size: 1rem; }
.journey-card span, .cta-card span, .topic-card span, .checklist-card p { color: var(--muted); margin: 0; }
.start-link { align-self: end; color: var(--link); font-weight: 750; }
.article-pagination { display: grid; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); gap: .85rem; margin-top: 2.25rem; padding-top: 1rem; border-top: 1px solid var(--border); }
.article-pagination a { padding: .85rem 1rem; border: 1px solid var(--border); border-radius: .35rem; background: var(--surface-muted); text-decoration: none; font-weight: 700; }

@media (max-width: 980px) {
  .layout-shell { grid-template-columns: minmax(0, 1fr); max-width: 52rem; }
  .site-sidebar { position: static; max-height: none; padding: 1rem; border: 1px solid var(--border); background: var(--surface-muted); }
  .article-grid { grid-template-columns: 1fr; }
  .desktop-toc { display: none; }
  .mobile-toc { display: block; }
}
@media (max-width: 720px) {
  .nav-toggle { display: inline-flex; min-height: 2.35rem; align-items: center; padding: .45rem .7rem; border: 1px solid var(--border); border-radius: .35rem; background: var(--surface); color: var(--heading); font: inherit; font-weight: 700; }
  .site-menu { display: none; position: absolute; left: 1rem; right: 1rem; top: 4rem; padding: .75rem; border: 1px solid var(--border); background: var(--surface); }
  .nav-open .site-menu { display: grid; }
  .layout-shell { width: min(100% - 1.25rem, 52rem); }
}