:root {
  --black: #000;
  --white: #fff;
  --gray-50: #fafafa;
  --gray-100: #f5f5f5;
  --gray-200: #e5e5e5;
  --gray-400: #a3a3a3;
  --gray-500: #737373;
  --gray-700: #404040;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif;
  color: var(--black);
  background: var(--white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--black); }
.site-header {
  border-bottom: 1px solid var(--gray-200);
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(10px);
  position: sticky; top: 0; z-index: 10;
}
.site-header .inner {
  max-width: 64rem;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.brand { font-weight: 700; text-decoration: none; font-size: 0.95rem; }
.site-header nav { display: flex; gap: 1rem; }
.site-header nav a {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--gray-500);
  text-decoration: none;
}
.site-header nav a:hover { color: var(--black); }
.article {
  max-width: 44rem;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
}
.article h1 {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;
}
.article h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin: 1.5rem 0 0.5rem;
}
.article h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 1rem 0 0.4rem;
}
.article p, .article li { font-size: 0.98rem; color: var(--gray-700); }
.article p { margin: 0.5rem 0; }
.article ul, .article ol { padding-left: 1.5rem; margin: 0.5rem 0 1rem; }
.article ul li, .article ol li { margin: 0.25rem 0; }
.article a { text-decoration: underline; }
.back { margin-top: 2rem; font-size: 0.9rem; }
.faq details {
  border: 1px solid var(--gray-200);
  border-radius: 0.5rem;
  padding: 0.85rem 1rem;
  margin: 0.5rem 0;
  background: var(--white);
}
.faq summary { cursor: pointer; font-weight: 600; font-size: 0.98rem; }
.faq details[open] summary { margin-bottom: 0.5rem; }
.site-footer {
  border-top: 1px solid var(--gray-200);
  background: var(--gray-50);
}
.site-footer .inner {
  max-width: 64rem;
  margin: 0 auto;
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  font-size: 0.8rem;
  color: var(--gray-500);
}
.site-footer a { color: var(--gray-500); margin: 0 0.25rem; text-decoration: none; }
.site-footer a:hover { color: var(--black); text-decoration: underline; }
@media (max-width: 520px) {
  .site-header nav a { font-size: 0.65rem; }
  .article h1 { font-size: 1.75rem; }
}