:root {
  color-scheme: light dark;
  --bg: #f7f7f4;
  --surface: rgba(255, 255, 255, 0.86);
  --surface-strong: #ffffff;
  --text: #181817;
  --muted: #666662;
  --line: rgba(24, 24, 23, 0.12);
  --accent: #1473e6;
  --accent-soft: #e7f0ff;
  --sunday: #cc2621;
  --saturday: #1473e6;
  --shadow: 0 18px 55px rgba(20, 25, 30, 0.08);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(circle at 12% 0%, rgba(20, 115, 230, 0.09), transparent 33rem),
    var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 16px;
  line-height: 1.8;
}

a { color: var(--accent); }

a:focus-visible,
summary:focus-visible {
  outline: 3px solid rgba(20, 115, 230, 0.35);
  outline-offset: 3px;
  border-radius: 6px;
}

.wrap {
  width: min(100% - 40px, 820px);
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--bg) 84%, transparent);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.header-inner {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 760;
  text-decoration: none;
  letter-spacing: -0.02em;
}

.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  background: var(--text);
  color: var(--bg);
  font-size: 17px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.12);
}

nav {
  display: flex;
  gap: 20px;
  font-size: 14px;
}

nav a {
  color: var(--muted);
  font-weight: 650;
  text-decoration: none;
}

nav a[aria-current="page"] { color: var(--text); }

.hero { padding: 78px 0 52px; }

.eyebrow {
  margin: 0 0 14px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.14em;
}

h1 {
  max-width: 720px;
  margin: 0;
  font-size: clamp(2.35rem, 8vw, 4.8rem);
  line-height: 1.08;
  letter-spacing: -0.055em;
}

h1 span { color: var(--muted); }

.lead {
  max-width: 650px;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: clamp(1.02rem, 2.5vw, 1.22rem);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 10px 18px;
  border: 1px solid var(--text);
  border-radius: 999px;
  background: var(--text);
  color: var(--bg);
  font-weight: 730;
  text-decoration: none;
}

.button.secondary {
  border-color: var(--line);
  background: var(--surface);
  color: var(--text);
}

.calendar-card {
  margin-top: 44px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.calendar-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 18px;
  font-weight: 760;
}

.week-row {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 8px;
  text-align: center;
}

.week-row span {
  min-height: 66px;
  padding-top: 8px;
  border-radius: 12px;
  background: color-mix(in srgb, var(--surface-strong) 70%, transparent);
  font-size: 12px;
  font-weight: 700;
}

.week-row strong {
  display: block;
  margin-top: 4px;
  font-size: 18px;
}

.week-row .sun { color: var(--sunday); }
.week-row .sat { color: var(--saturday); }
.week-row .today { background: var(--accent-soft); color: var(--accent); }

.content { padding-bottom: 80px; }

.content > section,
.content > article,
article.content section {
  margin-top: 22px;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--surface);
}

article.content { padding-bottom: 80px; }

article.content section:first-child { margin-top: 0; }

h2 {
  margin: 0 0 14px;
  font-size: clamp(1.25rem, 3vw, 1.55rem);
  line-height: 1.35;
  letter-spacing: -0.025em;
}

h3 { margin: 22px 0 8px; font-size: 1.05rem; }

p { margin: 0.7em 0; }

ul { padding-left: 1.35em; }

li + li { margin-top: 6px; }

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  margin-top: 22px;
  color: var(--muted);
  font-size: 14px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 22px;
}

.feature {
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--surface);
}

.feature strong { display: block; margin-bottom: 4px; }
.feature p { margin: 0; color: var(--muted); font-size: 14px; }

.language-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 34px;
}

.language-card {
  display: block;
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--surface);
  color: var(--text);
  text-decoration: none;
  box-shadow: var(--shadow);
  transition: transform 160ms ease, border-color 160ms ease;
}

.language-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
}

.language-card strong {
  display: block;
  font-size: 1.25rem;
}

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

.faq details {
  border-top: 1px solid var(--line);
  padding: 17px 0;
}

.faq details:last-child { padding-bottom: 0; }
.faq details:first-of-type { border-top: 0; }

.faq summary {
  cursor: pointer;
  font-weight: 720;
}

.faq details p { color: var(--muted); }

.contact {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.contact p { color: var(--muted); }

.notice {
  padding: 16px 18px;
  border-left: 4px solid var(--accent);
  border-radius: 8px 14px 14px 8px;
  background: var(--accent-soft);
}

.page-links {
  margin-top: 38px;
  color: var(--muted);
  font-size: 14px;
}

.site-footer {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}

.footer-inner {
  min-height: 92px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.footer-links { display: flex; flex-wrap: wrap; gap: 18px; }
.footer-links a { color: inherit; }

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0b0b;
    --surface: rgba(30, 30, 29, 0.88);
    --surface-strong: #242423;
    --text: #f5f5f2;
    --muted: #aaa9a4;
    --line: rgba(255, 255, 255, 0.12);
    --accent: #73aeff;
    --accent-soft: #172b46;
    --sunday: #ff7b76;
    --saturday: #73aeff;
    --shadow: 0 18px 55px rgba(0, 0, 0, 0.28);
  }
}

@media (max-width: 640px) {
  .wrap { width: min(100% - 28px, 820px); }
  .site-header { position: static; }
  .header-inner { min-height: auto; padding: 16px 0; align-items: flex-start; }
  nav { flex-direction: column; gap: 4px; text-align: right; }
  .hero { padding: 52px 0 34px; }
  .calendar-card { padding: 15px; }
  .week-row { gap: 4px; }
  .week-row span { min-height: 55px; }
  .feature-grid { grid-template-columns: 1fr; }
  .language-grid { grid-template-columns: 1fr; }
  .content > section, .content > article, article.content section { padding: 21px; }
  .contact, .footer-inner { align-items: flex-start; flex-direction: column; }
  .footer-inner { padding: 24px 0; }
}