:root {
  color-scheme: light dark;
  --bg: #fafafa;
  --fg: #18181b;
  --muted: #52525b;
  --faint: #71717a;
  --line: #e4e4e7;
  --card: #ffffff;
  --soft: #f4f4f5;
  --accent: #2563eb;
  --shadow: rgba(79, 70, 229, 0.22);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #09090b;
    --fg: #fafafa;
    --muted: #a1a1aa;
    --faint: #71717a;
    --line: #27272a;
    --card: rgba(24, 24, 27, 0.55);
    --soft: rgba(24, 24, 27, 0.55);
    --accent: #60a5fa;
    --shadow: rgba(79, 70, 229, 0.28);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
}
a { color: var(--accent); }
.wrap { max-width: 48rem; margin: 0 auto; padding: 0 1.5rem; }
.top {
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  position: sticky;
  top: 0;
}
.top .wrap { display: flex; align-items: center; justify-content: space-between; height: 4rem; }
.brand { display: flex; align-items: center; gap: 0.6rem; color: inherit; text-decoration: none; font-weight: 600; }
.brand img { width: 1.75rem; height: 1.75rem; border-radius: 0.45rem; }
.nav { display: flex; gap: 1.25rem; font-size: 0.875rem; }
.nav a { color: var(--muted); text-decoration: none; }
.nav a:hover { color: var(--fg); }
.hero { padding: 4rem 0 2.5rem; text-align: center; }
.hero img { width: 6rem; height: 6rem; border-radius: 1.35rem; box-shadow: 0 12px 30px var(--shadow); }
h1 { margin: 1.5rem 0 0; font-size: clamp(2.25rem, 5vw, 3rem); letter-spacing: -0.03em; }
.lead { margin: 1rem auto 0; max-width: 36rem; font-size: 1.125rem; color: var(--muted); }
.en { margin: 0.5rem auto 0; max-width: 36rem; font-size: 0.875rem; color: var(--faint); }
.grid { display: grid; grid-template-columns: 1fr; gap: 1rem; }
@media (min-width: 640px) { .grid { grid-template-columns: 1fr 1fr; } }
.card { border: 1px solid var(--line); background: var(--card); border-radius: 1rem; padding: 1.25rem; }
.card h2, .faq h2, .box h2 { margin: 0; font-size: 1rem; }
.card p { margin: 0.4rem 0 0; font-size: 0.875rem; color: var(--muted); }
.section { padding: 4rem 0; }
.section > h2 { font-size: 1.5rem; letter-spacing: -0.02em; margin: 0; }
.section > p { color: var(--muted); }
.btn {
  display: inline-flex;
  margin-top: 1.25rem;
  background: #2563eb;
  color: white;
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.75rem 1.25rem;
  border-radius: 0.75rem;
  box-shadow: 0 10px 24px rgba(37, 99, 235, 0.25);
}
.btn:hover { background: #3b82f6; }
.faq { margin-top: 2.5rem; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
details { padding: 1rem 0; border-bottom: 1px solid var(--line); }
details:last-child { border-bottom: 0; }
summary { cursor: pointer; font-weight: 500; list-style: none; display: flex; justify-content: space-between; gap: 1rem; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; color: var(--faint); }
details[open] summary::after { content: "–"; }
details p { margin: 0.5rem 0 0; font-size: 0.875rem; color: var(--muted); }
.box { margin-top: 3rem; background: var(--soft); border-radius: 1rem; padding: 1.5rem; }
.box p { margin: 0.5rem 0 0; font-size: 0.875rem; color: var(--muted); }
.page { padding: 3.5rem 0 4rem; }
.page h1 { font-size: 1.875rem; margin: 0; text-align: left; }
.meta { margin: 0.5rem 0 0; font-size: 0.875rem; color: var(--faint); }
.page h2 { margin: 3.5rem 0 0; font-size: 1.875rem; letter-spacing: -0.02em; }
.page h3 { margin: 2rem 0 0; font-size: 1.125rem; }
.page p { margin: 0.5rem 0 0; color: var(--muted); }
.foot { border-top: 1px solid var(--line); padding: 2rem 0; color: var(--faint); font-size: 0.875rem; }
.foot .wrap { display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap; }
.foot a { color: var(--faint); text-decoration: none; }
.foot a:hover { color: var(--fg); }