:root {
  --bg: #f7f7f8;
  --shell: #fafafa;
  --ink: #161616;
  --mute: #666666;
  --line: #e7e7e7;
  --card: #ffffff;
  --radius: 0.5rem;
  --page-pad: clamp(2rem, 8vw, 7.5rem);
  --page-max: 80rem;
  --page-inset: max(var(--page-pad), calc((100% - var(--page-max)) / 2));
}
* { box-sizing: border-box; }
/* 整体密度约 90%：只改根字号，不用 zoom/scale。 */
html { font-size: 90%; scrollbar-gutter: stable; }
html, body {
  margin: 0;
  padding: 0;
  background: var(--shell);
  color: var(--ink);
  font-family: Inter, "Segoe UI", "Helvetica Neue", sans-serif;
  line-height: 1.5;
}
a { color: inherit; cursor: pointer; }
.btn, .brand, .top nav a, .foot a {
  cursor: pointer;
  transition: color 180ms ease, background-color 180ms ease, border-color 180ms ease;
}
.btn:focus-visible, a:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}
@media (prefers-reduced-motion: reduce) {
  .btn, .brand, .top nav a, .foot a { transition: none; }
}
main a { text-decoration: none; border-bottom: 1px solid var(--line); }
main a:hover { border-bottom-color: var(--ink); }
.site {
  width: 100%;
  background: var(--shell);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
.top {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 0.875rem var(--page-inset);
  border-bottom: 1px solid var(--line);
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  text-decoration: none;
  justify-self: start;
}
.brand img { width: 1.75rem; height: 1.75rem; }
.top nav { display: flex; gap: 1.75rem; font-size: 0.875rem; color: var(--mute); }
.top .btn { justify-self: end; }
.top nav a { text-decoration: none; }
.top nav a:hover { color: var(--ink); }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.25rem;
  padding: 0 0.875rem;
  border-radius: 0.4375rem;
  text-decoration: none;
  font-size: 0.8125rem;
  font-weight: 500;
  border: 1px solid var(--line);
  background: var(--card);
}
.btn:hover { background: #f3f3f3; }
main {
  width: min(47.5rem, calc(100% - 2 * var(--page-inset)));
  margin: 0 auto;
  padding: 3rem 0 5rem;
  flex: 1;
}
h1 {
  font-size: 2.25rem;
  font-weight: 600;
  letter-spacing: -0.04em;
  line-height: 1.15;
  margin: 0 0 1rem;
}
h2 {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.03em;
  margin: 2.25rem 0 0.75rem;
}
h3 {
  font-size: 1rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
}
p { margin: 0 0 1rem; }
.eyebrow {
  margin: 0 0 0.5rem;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--mute);
}
.lead { font-size: 1.0625rem; color: var(--mute); margin: 0 0 1.75rem; }
.meta { font-size: 0.8125rem; color: var(--mute); margin: -0.25rem 0 1.5rem; }
.crumbs { font-size: 0.8125rem; color: var(--mute); margin: 0 0 1.25rem; }
.crumbs a { border-bottom: none; color: var(--mute); }
.crumbs a:hover { color: var(--ink); }
.toc {
  margin: 0 0 2rem;
  padding: 1rem 1.125rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
}
.toc p {
  margin: 0 0 0.5rem;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--mute);
}
.toc ol { margin: 0; padding-left: 1.2em; }
.toc li { margin: 0.35rem 0; }
.toc a { border-bottom: none; }
.toc a:hover { color: var(--ink); }
.path { list-style: none; margin: 0 0 2rem; padding: 0; display: grid; gap: 0.75rem; }
.path li {
  margin: 0;
  padding: 0.875rem 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
}
.path b { display: block; }
.path span { display: block; margin-top: 0.25rem; color: var(--mute); font-size: 0.875rem; }
.cards { display: grid; gap: 0.75rem; margin: 0 0 2rem; }
a.card {
  display: block;
  padding: 1.125rem 1.25rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  text-decoration: none;
  border-bottom: none;
}
a.card:hover { background: #f3f3f3; border-color: var(--ink); }
.card strong { display: block; margin-bottom: 0.25rem; }
.card span { color: var(--mute); font-size: 0.875rem; }
.callout {
  margin: 0 0 1.5rem;
  padding: 0.875rem 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  font-size: 0.875rem;
}
.table-wrap {
  overflow: auto;
  margin: 0 0 1.5rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
}
table { width: 100%; border-collapse: collapse; font-size: 0.875rem; }
th, td { text-align: left; padding: 0.55rem 0.75rem; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-weight: 600; color: var(--mute); font-size: 0.75rem; }
tr:last-child th, tr:last-child td { border-bottom: none; }
.faq dt { font-weight: 600; margin-top: 1rem; }
.faq dd { margin: 0.35rem 0 0; }
pre {
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: auto;
  background: var(--card);
  color: var(--ink);
  font-size: 0.8125rem;
  margin: 0 0 1.25rem;
}
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; }
.mute { color: var(--mute); }
ul { padding-left: 1.1em; }
li { margin: 0.5rem 0; }
main a.btn { border-bottom: none; }
.foot {
  border-top: 1px solid var(--line);
  padding: 1.25rem var(--page-inset) 1.75rem;
  color: var(--mute);
  font-size: 0.8125rem;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.foot a { text-decoration: none; }
.foot a:hover { color: var(--ink); }
@media (max-width: 800px) {
  .top { grid-template-columns: 1fr auto; }
  .top nav { display: none; }
  .top, .foot { padding-left: var(--page-inset); padding-right: var(--page-inset); }
  main { width: min(47.5rem, calc(100% - 2 * var(--page-inset))); }
}