:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --text: #1c1c1e;
  --muted: #5c5c61;
  --line: #e2e2e7;
  --accent: #3b3bd1;
  --chip: #f2f2f7;
  --on-accent: #ffffff;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --text: #f2f2f7;
    --muted: #a1a1a8;
    --line: #2c2c2e;
    --accent: #9a9aff;
    --chip: #1c1c1e;
    --on-accent: #000000;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "PingFang SC", "PingFang TC",
    "Apple SD Gothic Neo", "Noto Sans", "Noto Sans CJK JP", "Noto Sans Devanagari", Roboto, Helvetica, Arial, sans-serif;
}
.wrap { max-width: 42rem; margin: 0 auto; padding: 2rem 1.25rem 4rem; }
h1 { font-size: 1.75rem; line-height: 1.25; margin: 0 0 0.5rem; }
h2 { font-size: 1.2rem; margin: 2rem 0 0.5rem; scroll-margin-top: 1rem; }
h2:target { text-decoration: underline; text-decoration-color: var(--accent); text-underline-offset: 0.3em; }
h3 { font-size: 1.05rem; margin: 1.5rem 0 0.35rem; }
p { margin: 0 0 1rem; }
.updated { color: var(--muted); font-size: 0.9rem; }
a { color: var(--accent); }
.top { display: flex; align-items: center; justify-content: space-between; gap: 1rem; margin: 0 0 2rem; }
.top .brand { margin: 0; }
details.lang { position: relative; }
details.lang > summary {
  display: inline-flex; align-items: center; gap: 0.5rem; min-height: 2.75rem; padding: 0.4rem 0.9rem;
  border: 1px solid var(--line); border-radius: 999px; background: var(--chip); color: var(--text);
  cursor: pointer; list-style: none; font-size: 0.95rem; user-select: none; -webkit-tap-highlight-color: transparent;
}
details.lang > summary::-webkit-details-marker { display: none; }
details.lang > summary svg { flex: none; color: var(--accent); }
details.lang > summary::after {
  content: ""; width: 0.45rem; height: 0.45rem; margin-left: 0.15rem; border: solid var(--muted); border-width: 0 2px 2px 0;
  transform: translateY(-0.12rem) rotate(45deg); transition: transform 0.15s ease;
}
details.lang[open] > summary { border-color: var(--accent); }
details.lang[open] > summary::after { transform: translateY(0.1rem) rotate(-135deg); }
details.lang > summary:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
details.lang ul {
  position: absolute; z-index: 10; right: 0; top: calc(100% + 0.5rem); width: min(19rem, calc(100vw - 2.5rem));
  max-height: min(40rem, calc(100vh - 7.5rem)); max-height: min(40rem, calc(100dvh - 7.5rem)); overflow-y: auto; margin: 0; padding: 0.35rem; list-style: none;
  background: var(--bg); border: 1px solid var(--line); border-radius: 0.9rem; box-shadow: 0 12px 32px rgba(0, 0, 0, 0.18);
}
details.lang li a {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem; min-height: 2.75rem; padding: 0.5rem 0.75rem;
  border-radius: 0.6rem; color: var(--text); text-decoration: none; font-size: 1rem;
}
details.lang li a:hover { background: var(--chip); }
details.lang li a:focus-visible { outline: 3px solid var(--accent); outline-offset: -3px; }
details.lang li a[aria-current="page"] { color: var(--accent); font-weight: 600; }
details.lang li a[aria-current="page"]::after { content: "\2713"; }
@media print { .top { display: none; } }
.button {
  display: inline-block; margin: 0.25rem 0 1.5rem; padding: 0.8rem 1.4rem; border-radius: 0.8rem; background: var(--accent);
  color: var(--on-accent); font-weight: 600; text-decoration: none;
}
.button:hover { filter: brightness(1.08); }
.button:focus-visible { outline: 3px solid var(--text); outline-offset: 3px; }
details.faq { border-top: 1px solid var(--line); }
details.faq:last-of-type { border-bottom: 1px solid var(--line); }
details.faq > summary {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem; min-height: 3rem; padding: 0.85rem 0.25rem;
  cursor: pointer; list-style: none; font-weight: 600; -webkit-tap-highlight-color: transparent;
}
details.faq > summary::-webkit-details-marker { display: none; }
details.faq > summary::after {
  content: ""; flex: none; width: 0.5rem; height: 0.5rem; border: solid var(--muted); border-width: 0 2px 2px 0;
  transform: translateY(-0.1rem) rotate(45deg); transition: transform 0.15s ease;
}
details.faq[open] > summary::after { transform: translateY(0.1rem) rotate(-135deg); }
details.faq > summary:focus-visible { outline: 3px solid var(--accent); outline-offset: -3px; border-radius: 0.4rem; }
details.faq > p { margin: 0 0.25rem 1rem; }
.links { display: flex; flex-wrap: wrap; gap: 0.5rem 1.5rem; margin: 2rem 0 0; padding: 0; list-style: none; font-size: 0.95rem; }
.brand { font-weight: 700; color: var(--muted); letter-spacing: 0.02em; margin: 0 0 1.5rem; }
.chooser { list-style: none; padding: 0; margin: 1.5rem 0 0; display: grid; gap: 0.6rem; }
.chooser a {
  display: block; padding: 0.9rem 1rem; border: 1px solid var(--line); border-radius: 0.75rem;
  background: var(--chip); color: var(--text); text-decoration: none; font-size: 1.05rem;
}
.chooser a:hover { border-color: var(--accent); }