* { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #fbfbfd;
  --surface: #ffffff;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --line: #e5e5ea;
  --accent: #0a84ff;
  --accent-soft: #f0f0f3;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Hiragino Sans",
               "Noto Sans JP", "Noto Sans KR", "Noto Sans SC", "Noto Sans TC", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
}

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

/* ---- Language tabs ---- */
.lang-tabs {
  display: none; /* JS 有効時のみ表示 */
  position: sticky;
  top: 0;
  z-index: 10;
  gap: 6px;
  overflow-x: auto;
  padding: 10px 16px;
  background: rgba(255, 255, 255, 0.92);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
  scrollbar-width: none;
}
.lang-tabs::-webkit-scrollbar { display: none; }

.lang-tab {
  flex: 0 0 auto;
  padding: 7px 14px;
  border: none;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--muted);
  font: inherit;
  font-size: 0.85rem;
  line-height: 1.2;
  cursor: pointer;
  white-space: nowrap;
  transition: background .15s, color .15s;
}
.lang-tab:hover { background: #e5e5ea; }
.lang-tab[aria-selected="true"] {
  background: var(--text);
  color: #fff;
}

html.js .lang-tabs { display: flex; }

/* 言語ごとのセクション。JS 無効時は日本語のみ表示 */
[data-lang] { display: none; }
[data-lang="ja"] { display: block; }
html.js [data-lang] { display: none; }
html.js [data-lang].is-active { display: block; }

/* ---- Landing (index) ---- */
.hero {
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  text-align: center;
  padding: 72px 24px 64px;
}
.hero-icon {
  width: 100px;
  height: 100px;
  border-radius: 22px;
  border: 1px solid var(--line);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.05);
  margin-bottom: 24px;
}
.hero h1 {
  font-size: 2.2rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 12px;
}
.hero p {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 420px;
  margin: 0 auto 36px;
}
.badge img {
  height: 52px;
  transition: opacity .2s;
}
.badge img:hover { opacity: 0.85; }

.features {
  max-width: 720px;
  margin: 0 auto;
  padding: 64px 24px;
}
.section-title {
  font-size: 1.6rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 40px;
  letter-spacing: -0.3px;
}
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}
.feature-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 28px 24px;
}
.feature-icon {
  font-size: 2rem;
  margin-bottom: 14px;
  line-height: 1;
}
.feature-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}
.feature-card p {
  font-size: 0.9rem;
  color: var(--muted);
}

footer {
  text-align: center;
  padding: 32px 24px 40px;
  font-size: 0.85rem;
  color: var(--muted);
}
footer a {
  color: var(--muted);
  text-decoration: none;
  margin: 0 10px;
  white-space: nowrap;
}
footer a:hover { text-decoration: underline; }

/* ---- Document pages (privacy / terms) ---- */
.doc {
  max-width: 680px;
  margin: 0 auto;
  padding: 40px 20px 64px;
}
.doc h1 { font-size: 1.6rem; margin-bottom: 4px; }
.doc h2 { font-size: 1.1rem; margin-top: 2rem; margin-bottom: 0.4rem; color: var(--text); }
.doc p, .doc li { font-size: 0.95rem; }
.doc ul { padding-left: 1.4em; margin: 0.2rem 0; }
.doc li { margin: 4px 0; }
.doc a { text-decoration: none; }
.doc a:hover { text-decoration: underline; }
.updated { font-size: 0.85rem; color: var(--muted); margin-bottom: 1.5rem; }

.back {
  font-size: 0.9rem;
  color: var(--accent);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-bottom: 24px;
}
.back:hover { text-decoration: underline; }

/* ---- Support ---- */
.support {
  max-width: 680px;
  margin: 0 auto;
  padding: 40px 20px 64px;
}
.support h1 { font-size: 1.6rem; font-weight: 700; margin-bottom: 8px; }
.subtitle { font-size: 0.9rem; color: var(--muted); margin-bottom: 32px; }
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 28px;
  margin-bottom: 16px;
}
.card h2 { font-size: 1rem; font-weight: 600; margin-bottom: 12px; }
.card p, .card li { font-size: 0.95rem; color: var(--muted); }
.card ul { padding-left: 1.4em; margin: 0.2rem 0; }
.card li { margin: 4px 0; }
.contact-btn {
  display: inline-block;
  margin-top: 16px;
  padding: 12px 24px;
  background: var(--text);
  color: #fff;
  border-radius: 10px;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 600;
}
.contact-btn:hover { background: #000; }