:root {
  --text: #1a1a1a;
  --muted: #5c6670;
  --border: #e5e5e5;
  --link: #1a6574;
  --bg: #fff;
  --teal: #217a8c;
  --teal-dark: #165868;
  --max: 42rem;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", Meiryo, sans-serif;
  font-size: 16px;
  line-height: 1.8;
}

body.lang-en {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

body.lang-ko {
  font-family: "Apple SD Gothic Neo", "Noto Sans KR", "Malgun Gothic", sans-serif;
}

body.lang-zh-tw {
  font-family: "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
}

.nav {
  border-bottom: 1px solid var(--border);
  background: #fff;
}

.nav-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0.85rem 1.25rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  align-items: center;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
}

.nav a:hover,
.nav a.current {
  color: var(--teal-dark);
  text-decoration: underline;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  color: var(--teal-dark);
  font-weight: 700;
  text-decoration: none;
  margin-right: auto;
}

.lang-switch {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 0.35rem;
  row-gap: 0.2rem;
  margin-left: 0.25rem;
}

.lang-switch__link {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.lang-switch__link:hover,
.lang-switch__link.is-current {
  color: var(--teal-dark);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.lang-switch__sep {
  color: #c5ccd3;
  font-size: 0.82rem;
  user-select: none;
}

.brand:hover,
.brand.current {
  text-decoration: none;
}

.brand-icon {
  display: block;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 3rem 1.25rem 4rem;
}

header {
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}

h1 {
  margin: 0 0 0.75rem;
  font-size: 1.75rem;
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: 0.02em;
}

.lead {
  margin: 0;
  font-size: 1.05rem;
}

.updated,
.app-name {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

h2 {
  margin: 2.25rem 0 0.85rem;
  font-size: 1.1rem;
  font-weight: 700;
  line-height: 1.45;
}

p { margin: 0 0 1rem; }

ul, ol {
  margin: 0 0 1rem;
  padding-left: 1.25rem;
}

li { margin-bottom: 0.35rem; }

a {
  color: var(--link);
  word-break: break-all;
}

a:hover { text-decoration: underline; }

.hero {
  background: linear-gradient(160deg, var(--teal-dark), var(--teal));
  color: #fff;
  padding: 3rem 1.25rem 3.25rem;
}

.hero .wrap {
  padding: 0;
}

.hero h1 {
  color: #fff;
  font-size: 1.85rem;
}

.hero p {
  color: rgba(255, 255, 255, 0.92);
}

.hero .updated { color: rgba(255, 255, 255, 0.75); }

.cta {
  display: inline-block;
  margin: 0.25rem 0.5rem 0.25rem 0;
  padding: 0.7rem 1.1rem;
  border-radius: 999px;
  background: var(--teal);
  color: #fff !important;
  text-decoration: none !important;
  font-weight: 700;
}

.cta.secondary {
  background: #fff;
  color: var(--teal-dark) !important;
  border: 1px solid rgba(255, 255, 255, 0.4);
}

footer {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.875rem;
}

@media (min-width: 640px) {
  .wrap { padding: 4rem 1.5rem 5rem; }
  h1 { font-size: 2rem; }
  .hero h1 { font-size: 2.15rem; }
}