* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: #f6f7f9;
  color: #1a1a2e;
  line-height: 1.8;
}
.nav {
  background: #fff;
  border-bottom: 1px solid #e5e7eb;
  padding: 14px 0;
  position: sticky;
  top: 0;
  z-index: 10;
}
.nav-inner {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav .logo { font-weight: 800; font-size: 18px; text-decoration: none; color: #1a1a2e; }
.nav .logo span { color: #4f46e5; }
.nav a.back { font-size: 13px; color: #6b7280; text-decoration: none; }
.article {
  max-width: 760px;
  margin: 0 auto;
  padding: 32px 16px 60px;
}
.article h1 { font-size: 28px; margin-bottom: 8px; }
.article .meta { color: #9ca3af; font-size: 13px; margin-bottom: 24px; }
.article h2 {
  font-size: 20px;
  margin: 32px 0 12px;
  padding-left: 12px;
  border-left: 4px solid #4f46e5;
}
.article h3 { font-size: 16px; margin: 20px 0 8px; }
.article p { margin-bottom: 12px; font-size: 15px; }
.article ul, .article ol { padding-left: 24px; margin-bottom: 12px; font-size: 15px; }
.article li { margin-bottom: 6px; }
.card {
  background: #fff;
  border-radius: 12px;
  padding: 20px;
  margin: 16px 0;
  border: 1px solid #e5e7eb;
}
.card.highlight { background: #eef2ff; border-color: #c7d2fe; }
.card.warning { background: #fef3c7; border-color: #fde68a; }
.card h3 { margin-top: 0; }
.exercise {
  background: #fff;
  border-radius: 12px;
  padding: 20px;
  margin: 16px 0;
  border: 1px solid #e5e7eb;
}
.exercise h4 { font-size: 16px; margin-bottom: 8px; color: #4f46e5; }
.exercise .params {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin: 8px 0;
}
.exercise .param {
  background: #f3f4f6;
  border-radius: 6px;
  padding: 4px 10px;
  font-size: 13px;
  color: #374151;
}
.table-wrap { overflow-x: auto; margin: 16px 0; }
table { width: 100%; border-collapse: collapse; font-size: 14px; background: #fff; }
th, td { border: 1px solid #e5e7eb; padding: 10px 12px; text-align: left; }
th { background: #f9fafb; font-weight: 700; }
.footer-nav {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 16px 40px;
}
.footer-nav .links { display: flex; flex-wrap: wrap; gap: 8px; }
.footer-nav a {
  background: #fff;
  border: 1px solid #e5e7eb;
  border-radius: 999px;
  padding: 8px 16px;
  font-size: 13px;
  text-decoration: none;
  color: #374151;
}
.footer-nav a:hover { border-color: #4f46e5; color: #4f46e5; }
.disclaimer {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 16px 40px;
  font-size: 12px;
  color: #9ca3af;
  text-align: center;
}