:root {
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-muted: #4a4a4a;
  --color-accent: #0057b8;
  --color-accent-dark: #003d82;
  --color-surface: #f4f6f9;
  --color-border: #d9dee5;
  --font-size-base: 18px;
  --max-width: 960px;
}

* { box-sizing: border-box; }

html {
  font-size: var(--font-size-base);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Hiragino Sans", "Yu Gothic", "Segoe UI", system-ui, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.8;
}

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

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--color-accent);
  color: #fff;
  padding: 0.75em 1.25em;
  z-index: 100;
}
.skip-link:focus {
  left: 0.5em;
  top: 0.5em;
}

header.site-header {
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  background: var(--color-bg);
  z-index: 10;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.header-nav {
  display: flex;
  gap: 1.25rem;
  align-items: center;
  flex-wrap: wrap;
}

.header-nav a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.95rem;
}
.header-nav a:hover,
.header-nav a:focus-visible {
  text-decoration: underline;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.15em;
  font-weight: 700;
  font-size: 1.25rem;
  text-decoration: none;
  color: var(--color-text);
}
.logo img {
  display: block;
}

.header-controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

button.toggle-btn {
  font: inherit;
  padding: 0.5em 1em;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  border-radius: 6px;
  cursor: pointer;
}
button.toggle-btn:hover,
button.toggle-btn:focus-visible {
  border-color: var(--color-accent);
  outline: 2px solid var(--color-accent);
  outline-offset: 1px;
}
button.toggle-btn[aria-pressed="true"] {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

main { max-width: var(--max-width); margin: 0 auto; padding: 0 1.25rem; }

main.narrow { max-width: 720px; }

.hero {
  padding: 4rem 0 3rem;
  text-align: center;
}
.hero h1 {
  font-size: 2.2rem;
  line-height: 1.5;
  margin: 0 0 1rem;
}
.hero p.lead {
  font-size: 1.15rem;
  color: var(--color-muted);
  max-width: 40em;
  margin: 0 auto 2rem;
}
.cta {
  display: inline-block;
  padding: 0.9em 2em;
  background: var(--color-accent);
  color: #fff;
  text-decoration: none;
  border-radius: 8px;
  font-weight: 700;
  font-size: 1.05rem;
}
.cta:hover, .cta:focus-visible {
  background: var(--color-accent-dark);
  outline: 2px solid var(--color-accent-dark);
  outline-offset: 2px;
}

section {
  padding: 3rem 0;
  border-top: 1px solid var(--color-border);
}

section h2 {
  font-size: 1.6rem;
  margin-bottom: 1.25rem;
}

.page-header {
  padding: 3rem 0 1rem;
}
.page-header h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 1.5rem;
}
.card h3 {
  margin-top: 0;
  font-size: 1.1rem;
}
.card p { margin-bottom: 0; color: var(--color-muted); }

.form-embed {
  max-width: 640px;
  margin-top: 1.5rem;
}
.form-embed iframe {
  width: 100%;
  max-width: 100%;
  border: 1px solid var(--color-border);
  border-radius: 10px;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 1.5rem 0;
}
.faq-item:first-child { padding-top: 0; }
.faq-item h3 {
  margin: 0 0 0.5rem;
  font-size: 1.1rem;
}
.faq-item p {
  margin: 0;
  color: var(--color-muted);
}

.legal h2 {
  font-size: 1.3rem;
  margin-top: 2.5rem;
  border-top: none;
  padding-top: 0;
}
.legal section {
  border-top: none;
  padding: 0.5rem 0;
}
.legal p, .legal li { color: var(--color-muted); }
.legal .updated {
  color: var(--color-muted);
  font-size: 0.9rem;
}

footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 1.25rem;
  text-align: center;
  color: var(--color-muted);
  font-size: 0.95rem;
}
footer .footer-links {
  display: flex;
  gap: 1.25rem;
  justify-content: center;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

[data-lang="en"] { display: none; }
html[data-active-lang="en"] [data-lang="ja"] { display: none; }
html[data-active-lang="en"] [data-lang="en"] { display: block; }
html[data-active-lang="en"] span[data-lang="en"],
html[data-active-lang="en"] strong[data-lang="en"] { display: inline; }

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #12161c;
    --color-text: #f0f2f5;
    --color-muted: #b7bfc9;
    --color-surface: #1b2028;
    --color-border: #2c333d;
    --color-accent: #4d9fff;
    --color-accent-dark: #2f7fe0;
  }
  .cta { color: #0a0f16; }
}