:root {
  color-scheme: light;
  --bg: #f5f1e8;
  --bg-deep: #1f2925;
  --surface: #fffdf8;
  --surface-strong: #f0eadf;
  --text: #1d2824;
  --muted: #5e6b65;
  --accent: #12684f;
  --accent-soft: rgba(18, 104, 79, 0.09);
  --warning: #8a4e13;
  --warning-soft: rgba(180, 107, 32, 0.1);
  --border: rgba(50, 69, 61, 0.18);
  --border-strong: rgba(18, 104, 79, 0.42);
  --shadow: 0 18px 50px rgba(43, 47, 37, 0.09);
  --radius: 0.85rem;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  min-width: 20rem;
  margin: 0;
  background:
    linear-gradient(90deg, transparent 0, transparent calc(50% - 34rem), rgba(18, 104, 79, 0.035) calc(50% - 34rem), rgba(18, 104, 79, 0.035) calc(50% - 33.94rem), transparent calc(50% - 33.94rem)),
    var(--bg);
  color: var(--text);
  font: 400 1rem/1.75 system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
a { color: inherit; }
a:focus-visible { outline: 3px solid var(--warning); outline-offset: 4px; }
[id] { scroll-margin-top: 6rem; }
.shell { width: min(1120px, calc(100% - 2rem)); margin-inline: auto; }
.reading-shell { width: min(980px, calc(100% - 2rem)); margin-inline: auto; }
.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.75rem;
  left: 0.75rem;
  padding: 0.65rem 0.9rem;
  border-radius: 0.65rem;
  background: var(--warning);
  color: var(--bg-deep);
  font-weight: 800;
  transform: translateY(-180%);
}
.skip-link:focus { transform: translateY(0); }

.site-header {
  position: sticky;
  z-index: 20;
  top: 0;
  border-bottom: 1px solid var(--border);
  background: rgba(245, 241, 232, 0.92);
  backdrop-filter: blur(18px);
}
.nav { display: flex; min-height: 4.5rem; align-items: center; justify-content: space-between; gap: 1rem; }
.brand { display: inline-flex; align-items: center; gap: 0.65rem; font-weight: 850; letter-spacing: 0.07em; text-decoration: none; }
.brand-mark {
  display: grid;
  width: 2rem;
  height: 2rem;
  place-items: center;
  border: 1px solid var(--border-strong);
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.8rem;
}
.nav-links { display: flex; flex-wrap: wrap; gap: 0.35rem; }
.nav-links a { display: inline-flex; min-height: 44px; align-items: center; padding: 0.55rem 0.75rem; border-radius: 0.55rem; color: var(--muted); font-size: 0.9rem; text-decoration: none; }
.nav-links a:hover { background: var(--accent-soft); color: var(--text); }

.breadcrumbs { display: flex; flex-wrap: wrap; gap: 0.45rem; margin: 0 0 2rem; padding: 0; color: var(--muted); font-size: 0.88rem; list-style: none; }
.breadcrumbs li:not(:last-child)::after { margin-left: 0.45rem; color: #86928c; content: "/"; }
.breadcrumbs a { text-decoration: none; }
.breadcrumbs a:hover { color: var(--accent); }
.eyebrow { margin: 0 0 0.8rem; color: var(--accent); font-size: 0.76rem; font-weight: 850; letter-spacing: 0.16em; text-transform: uppercase; }
h1, h2, h3 { letter-spacing: -0.035em; }
h1 { max-width: 15ch; margin: 0 0 1.2rem; font-size: clamp(2.8rem, 7vw, 5.5rem); line-height: 0.98; }
h2 { margin: 3rem 0 1rem; font-size: clamp(1.65rem, 4vw, 2.3rem); line-height: 1.15; }
h3 { margin: 2rem 0 0.75rem; font-size: 1.18rem; line-height: 1.35; }
p { margin: 0 0 1.1rem; }
.lead { max-width: 44rem; color: var(--muted); font-size: clamp(1.05rem, 2vw, 1.22rem); }
.article-hero { padding: clamp(4rem, 9vw, 7rem) 0 3rem; border-bottom: 1px solid var(--border); }
.article-hero h1 { max-width: 21ch; font-size: clamp(2.4rem, 5vw, 4.2rem); line-height: 1.06; }
.article-meta { display: flex; flex-wrap: wrap; gap: 0.6rem; margin-top: 1.8rem; }
.meta-chip { max-width: 100%; padding: 0.38rem 0.65rem; border: 1px solid var(--border); border-radius: 999px; color: var(--muted); font-size: 0.8rem; }

.article-layout { display: grid; grid-template-columns: minmax(0, 1fr) 15rem; align-items: start; gap: clamp(2rem, 7vw, 5rem); padding: 3rem 0 6rem; }
.article-body { max-width: 44rem; }
.article-body p, .article-body li { color: #3d4b45; }
.article-body ul, .article-body ol { display: grid; gap: 0.65rem; padding-left: 1.4rem; }
.article-body strong { color: var(--text); }
.article-body code { padding: 0.12rem 0.35rem; border: 1px solid var(--border); border-radius: 0.35rem; background: var(--surface); color: var(--accent); font-size: 0.9em; }
.toc { position: sticky; top: 6.5rem; padding: 1.1rem; border: 1px solid var(--border); border-radius: 0.75rem; background: rgba(255, 253, 248, 0.86); }
.toc strong { display: block; margin-bottom: 0.75rem; font-size: 0.82rem; letter-spacing: 0.08em; text-transform: uppercase; }
.toc ol { display: grid; gap: 0.5rem; margin: 0; padding: 0; list-style: none; }
.toc a { display: inline-flex; min-height: 36px; align-items: center; color: var(--muted); font-size: 0.88rem; text-decoration: none; }
.toc a:hover { color: var(--accent); }
.callout { margin: 1.8rem 0; padding: 1.25rem; border: 1px solid var(--border-strong); border-radius: 1rem; background: var(--accent-soft); }
.callout.warning { border-color: rgba(244, 189, 98, 0.45); background: var(--warning-soft); }
.callout strong { display: block; margin-bottom: 0.35rem; color: var(--accent); }
.callout.warning strong { color: var(--warning); }
.callout p:last-child { margin-bottom: 0; }
.answer-first { font-size: 1.08rem; font-weight: 650; color: var(--text) !important; }
.article-cover { margin: 0 0 2.4rem; }
.article-cover img { display: block; width: 100%; height: auto; border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }
.article-cover figcaption { margin-top: 0.7rem; color: var(--muted); font-size: 0.84rem; line-height: 1.55; }
.table-wrap { margin: 1.5rem 0 2rem; overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
table { width: 100%; border-collapse: collapse; font-size: 0.93rem; }
th, td { padding: 0.85rem 0.9rem; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
thead th { background: var(--surface-strong); color: var(--text); }
tbody th { min-width: 7rem; color: var(--text); }
tbody tr:last-child th, tbody tr:last-child td { border-bottom: 0; }
.fact-list { display: grid; gap: 0.7rem; margin: 1.6rem 0; }
.fact-list p { margin: 0; padding: 0.85rem 1rem; border-left: 3px solid var(--accent); background: var(--accent-soft); }
.faq-list { display: grid; gap: 0.75rem; }
.faq-list details { border: 1px solid var(--border); border-radius: 0.7rem; background: var(--surface); }
.faq-list summary { display: flex; min-height: 48px; align-items: center; padding: 0.8rem 1rem; color: var(--text); font-weight: 750; cursor: pointer; }
.faq-list details p { padding: 0 1rem 1rem; margin: 0; }
.sources { margin-top: 3.5rem; padding-top: 0.5rem; border-top: 3px solid var(--text); }
.sources ol { gap: 0.35rem; }
.sources a { color: var(--accent); text-underline-offset: 0.18em; }
.byline { margin-top: 2rem; padding: 1.1rem 1.2rem; border: 1px solid var(--border); background: var(--surface-strong); }
.byline p { margin: 0.25rem 0; font-size: 0.9rem; }
.action-list { margin: 1.5rem 0; padding: 0; list-style: none; counter-reset: action; }
.action-list li { display: grid; grid-template-columns: 2.2rem 1fr; gap: 0.8rem; padding: 1rem 0; border-bottom: 1px solid var(--border); counter-increment: action; }
.action-list li::before {
  display: grid;
  width: 2.2rem;
  height: 2.2rem;
  place-items: center;
  border-radius: 0.7rem;
  background: var(--accent-soft);
  color: var(--accent);
  font: 800 0.72rem/1 ui-monospace, "Cascadia Code", monospace;
  content: counter(action, decimal-leading-zero);
}
.article-nav { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; margin-top: 3.5rem; }
.article-nav a { min-height: 76px; padding: 1.1rem; border: 1px solid var(--border); border-radius: 0.7rem; background: var(--surface); text-decoration: none; }
.article-nav a:hover { border-color: var(--border-strong); }
.article-nav span { display: block; margin-bottom: 0.25rem; color: var(--muted); font-size: 0.75rem; text-transform: uppercase; }

.hub-hero { padding: clamp(4.5rem, 10vw, 8rem) 0 4rem; }
.hub-hero h1 { max-width: 11ch; }
.reading-order { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); margin-top: 3rem; border-block: 1px solid var(--border); }
.reading-order div { padding: 1rem; border-right: 1px solid var(--border); }
.reading-order div:last-child { border-right: 0; }
.reading-order b { display: block; color: var(--accent); font: 800 0.75rem/1.2 ui-monospace, "Cascadia Code", monospace; }
.reading-order span { display: block; margin-top: 0.35rem; color: var(--muted); font-size: 0.85rem; }
.article-list { padding: 2rem 0 7rem; }
.article-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
.article-card { display: flex; min-height: 20rem; flex-direction: column; justify-content: space-between; padding: 1.5rem; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); text-decoration: none; }
.article-card:hover { border-color: var(--border-strong); background: var(--surface-strong); }
.article-card .number { color: var(--accent); font: 800 0.76rem/1 ui-monospace, "Cascadia Code", monospace; }
.article-card h2 { margin: 1.6rem 0 0.7rem; font-size: clamp(1.45rem, 3vw, 2rem); }
.article-card p { color: var(--muted); }
.article-card .read { color: var(--accent); font-weight: 800; }
.button { display: inline-flex; min-height: 2.75rem; align-items: center; justify-content: center; padding: 0.7rem 1rem; border: 1px solid var(--accent); border-radius: 999px; color: var(--accent); font-weight: 800; text-decoration: none; }
.button:hover { background: var(--accent-soft); }

footer { padding: 2.5rem 0; border-top: 1px solid var(--border); color: var(--muted); font-size: 0.88rem; }
.footer-grid { display: flex; align-items: flex-start; justify-content: space-between; gap: 2rem; }
.footer-grid p { max-width: 48rem; margin: 0; }
.footer-grid a { flex: 0 0 auto; color: var(--accent); font-weight: 750; text-decoration: none; }

@media (max-width: 800px) {
  .article-layout { grid-template-columns: 1fr; }
  .toc { position: static; order: -1; }
  .reading-order { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .reading-order div:nth-child(2) { border-right: 0; }
  .reading-order div:nth-child(-n + 2) { border-bottom: 1px solid var(--border); }
}
@media (max-width: 620px) {
  [id] { scroll-margin-top: 9rem; }
  .nav { align-items: flex-start; flex-direction: column; gap: 0.55rem; padding: 0.8rem 0; }
  .nav-links { width: 100%; flex-wrap: nowrap; overflow-x: auto; }
  .nav-links a { white-space: nowrap; }
  .article-hero h1 { max-width: 100%; font-size: clamp(1.9rem, 9vw, 2.1rem); line-height: 1.14; overflow-wrap: anywhere; }
  .article-hero .lead { overflow-wrap: anywhere; }
  .article-grid, .article-nav { grid-template-columns: 1fr; }
  .reading-order { grid-template-columns: 1fr; }
  .reading-order div, .reading-order div:nth-child(2) { border-right: 0; border-bottom: 1px solid var(--border); }
  .reading-order div:last-child { border-bottom: 0; }
  .footer-grid { flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}