:root {
  color-scheme: dark;
  --bg: #0b1024;
  --surface: #171f38;
  --ink: #f4f6ff;
  --muted: #9aa6c7;
  --flame: #ff6b21;
  --flame-deep: #e6451f;
  --gold: #ffc747;
  --mint: #3ddb96;
  --sky: #5c8cff;
  --line: rgba(92, 140, 255, 0.28);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Hiragino Kaku Gothic ProN", sans-serif;
  background:
    radial-gradient(circle at 18% 88%, rgba(255, 107, 33, 0.22), transparent 28rem),
    radial-gradient(circle at 86% 8%, rgba(92, 140, 255, 0.22), transparent 22rem),
    linear-gradient(180deg, var(--bg) 0%, #10183a 64%, #090d1c 100%);
  color: var(--ink);
  line-height: 1.7;
}

main {
  max-width: 44rem;
  margin: 0 auto;
  padding: 2.75rem 1.25rem 4rem;
}

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.lang {
  display: flex;
  gap: 0.4rem;
  padding: 0.2rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(23, 31, 56, 0.72);
}

.lang a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.8rem;
  font-weight: 700;
  padding: 0.35rem 0.7rem;
  border-radius: 999px;
}

.lang a:hover,
.lang a:focus-visible {
  color: var(--ink);
}

.lang a[hreflang="ja"] {
  color: var(--bg);
  background: var(--gold);
}

body:has(#en:target) .lang a[hreflang="ja"],
html[data-lang="en"] .lang a[hreflang="ja"] {
  color: var(--muted);
  background: transparent;
}

body:has(#en:target) .lang a[hreflang="en"],
html[data-lang="en"] .lang a[hreflang="en"] {
  color: var(--bg);
  background: var(--gold);
}

.eyebrow {
  margin: 0 0 0.5rem;
  color: var(--gold);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.9rem, 6vw, 3rem);
  line-height: 1.15;
}

.lead,
.meta {
  margin: 0 0 1.5rem;
  color: var(--muted);
}

.meta { font-size: 0.92rem; }

.links {
  display: grid;
  gap: 1rem;
}

a.card {
  display: block;
  padding: 1.35rem 1.4rem;
  color: var(--ink);
  text-decoration: none;
  background: rgba(23, 31, 56, 0.82);
  border: 1px solid var(--line);
  border-radius: 1.1rem;
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.24);
}

a.card strong {
  display: block;
  color: var(--gold);
  font-size: 1.05rem;
  margin-bottom: 0.25rem;
}

a.card span { color: var(--muted); }

section,
article {
  background: rgba(23, 31, 56, 0.82);
  border: 1px solid var(--line);
  border-radius: 1.1rem;
  padding: 1.35rem;
  margin-bottom: 1rem;
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.22);
}

article { padding: 1.5rem 1.35rem; }

h2 {
  margin: 0 0 0.75rem;
  color: var(--sky);
  font-size: 1.05rem;
}

article h2 { margin: 1.75rem 0 0.7rem; }
article h2:first-child { margin-top: 0; }

p, li { color: var(--ink); }
ul { margin: 0; padding-left: 1.2rem; }
article ul { margin: 0.5rem 0 0; }
a { color: var(--gold); }

.contact {
  display: inline-block;
  margin-top: 0.35rem;
  font-weight: 700;
  word-break: break-all;
}

.faq {
  display: grid;
  gap: 1rem;
  margin: 0;
}

.faq-item {
  border-top: 1px solid var(--line);
  padding-top: 1rem;
}

.faq-item:first-child {
  border-top: 0;
  padding-top: 0;
}

.faq dt {
  font-weight: 800;
  margin: 0 0 0.35rem;
}

.faq dd {
  color: var(--muted);
  margin: 0;
}

.summary {
  margin: 0 0 1.25rem;
  padding: 1rem 1.1rem;
  border-left: 3px solid var(--gold);
  background: rgba(255, 199, 71, 0.08);
}

code {
  color: var(--gold);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.92em;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
}

.brand .eyebrow { margin: 0; }

.rocket {
  width: 2.4rem;
  height: 2.8rem;
  flex: 0 0 auto;
}

.i18n { display: none; }
.i18n-ja { display: block; }
#en:target { display: block; }

body:has(#en:target) .i18n-ja,
html[data-lang="en"] .i18n-ja { display: none; }

body:has(#en:target) .i18n-en,
html[data-lang="en"] .i18n-en { display: block; }

body:has(#ja:target) .i18n-ja,
html[data-lang="ja"] .i18n-ja { display: block; }

body:has(#ja:target) .i18n-en,
html[data-lang="ja"] .i18n-en { display: none; }

footer {
  margin-top: 2rem;
  color: var(--muted);
  font-size: 0.875rem;
}

@media (max-width: 520px) {
  .top {
    flex-direction: column;
    align-items: flex-start;
  }
}