:root {
  --bg: #f6f5f2;
  --ink: #1a1a1a;
  --muted: #5c5c5c;
  --line: #ddd9d0;
  --card: #fffefb;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "SF Pro Text", "PingFang SC", "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}
main {
  max-width: 40rem;
  margin: 0 auto;
  padding: 2.5rem 1.25rem 4rem;
}
h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 0.35rem;
}
.meta {
  color: var(--muted);
  font-size: 0.9rem;
  margin-bottom: 1.75rem;
}
nav {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 2rem;
  font-size: 0.9rem;
}
nav a {
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 3px;
}
section {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.25rem 1.35rem;
  margin-bottom: 1rem;
}
h2 {
  font-size: 1.05rem;
  margin: 0 0 0.55rem;
}
p, li { font-size: 0.98rem; color: var(--ink); }
p { margin: 0 0 0.7rem; }
p:last-child, ul:last-child { margin-bottom: 0; }
ul {
  margin: 0;
  padding-left: 1.2rem;
}
li { margin-bottom: 0.35rem; }
a { color: inherit; }
.lang-zh { display: none; }
html[lang="zh-Hans"] .lang-en { display: none; }
html[lang="zh-Hans"] .lang-zh { display: block; }
html[lang="zh-Hans"] nav .lang-zh { display: inline; }