:root {
  color-scheme: light dark;
  --page: #f2f9fc;
  --paper: #fff;
  --ink: #142b3a;
  --muted: #486275;
  --accent: #13658e;
  --accent-bg: #e5f4fb;
  --line: #d6e6ef;
}

@media (prefers-color-scheme: dark) {
  :root {
    --page: #101b24;
    --paper: #172632;
    --ink: #edf6fc;
    --muted: #b1c8d8;
    --accent: #8ed8ff;
    --accent-bg: #1e3b50;
    --line: #345167;
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", sans-serif;
  font-size: 1.05rem;
  line-height: 1.7;
  overflow-wrap: anywhere;
}
a { color: var(--accent); text-underline-offset: .19em; }
a:focus-visible { outline: .15rem solid var(--accent); outline-offset: .22rem; border-radius: .16rem; }
main {
  width: min(100% - 2rem, 53rem);
  margin: clamp(1rem, 5vw, 4rem) auto;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: clamp(1.1rem, 4vw, 2.15rem);
}
header, article, footer { padding-inline: clamp(1.1rem, 6vw, 4.5rem); }
header {
  padding-block: clamp(1.25rem, 5vw, 3rem) 1.4rem;
  background: var(--accent-bg);
  border-start-start-radius: inherit;
  border-start-end-radius: inherit;
  border-block-end: 1px solid var(--line);
}
.brand { color: var(--accent); font-weight: 700; margin: 0; }
h1, h2 { line-height: 1.24; text-wrap: balance; }
h1 { font-size: clamp(2.25rem, 7vw, 4rem); margin: .65rem 0 .35rem; letter-spacing: -.035em; }
header time { color: var(--muted); font-size: .94rem; }
nav { display: flex; flex-wrap: wrap; align-items: center; gap: .25rem .95rem; }
nav a, nav span { padding-block: .45rem; }
nav span { color: var(--ink); font-weight: 700; }
.document-nav { margin-block-start: 1rem; }
.language-nav { border-block-start: 1px solid var(--line); margin-block-start: .55rem; padding-block-start: .5rem; }
article { padding-block: 1.6rem 2.1rem; }
article > p:first-child { margin-block-start: 0; font-size: 1.13rem; }
article p { margin-block: .6rem 1rem; max-inline-size: 66ch; }
section + section { border-block-start: 1px solid var(--line); margin-block-start: 1.55rem; padding-block-start: 1.45rem; }
h2 { font-size: clamp(1.2rem, 3.8vw, 1.5rem); margin: 0 0 .75rem; }
footer { border-block-start: 1px solid var(--line); padding-block: 1rem 1.3rem; font-size: .94rem; }
[lang="zh-CN"] body { line-height: 1.82; }
@media (max-width: 28rem) {
  main { width: calc(100% - 1rem); }
}