/* 全ページ共通のヘッダー（rfc-translater と同じ明るいナビゲーションバー） */
.nt-nav { background: #f8f9fa; border-bottom: 1px solid #dee2e6; }
.nt-nav-inner { max-width: 1140px; margin: 0 auto; padding: .5rem 1rem; display: flex; align-items: center; gap: 1.1rem;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", sans-serif; }
.nt-brand { font-size: 1.25rem; color: rgba(0, 0, 0, .9); text-decoration: none; margin-right: .4rem; }
.nt-link { color: rgba(0, 0, 0, .55); text-decoration: none; font-size: .95rem; }
.nt-brand:hover, .nt-link:hover { color: rgba(0, 0, 0, .8); }
.nt-user { color: rgba(0, 0, 0, .55); }

/* テーマ切り替えボタン（ライトでは月、ダークでは太陽を表示し、押すとそのテーマに切り替える） */
.nt-theme { margin-left: auto; display: inline-flex; align-items: center; justify-content: center; width: 38px; height: 38px; padding: 0;
  border: 1px solid transparent; border-radius: 6px; background: transparent; color: rgba(0, 0, 0, .6); cursor: pointer; }
.nt-theme:hover { background: rgba(0, 0, 0, .06); color: rgba(0, 0, 0, .85); }
.nt-theme:focus-visible { outline: 3px solid #7cc4e4; outline-offset: 1px; }
.nt-theme + .nt-user { margin-left: .2rem; }
.nt-icon-sun { display: none; }
html.dark-theme .nt-icon-sun { display: block; }
html.dark-theme .nt-icon-moon { display: none; }

/* ダークテーマ */
html.dark-theme .nt-nav { background: #19191c; border-bottom-color: #2c2f33; }
html.dark-theme .nt-brand { color: #e1e4e8; }
html.dark-theme .nt-link, html.dark-theme .nt-user { color: #9aa3ad; }
html.dark-theme .nt-brand:hover, html.dark-theme .nt-link:hover { color: #fff; }
html.dark-theme .nt-theme { color: #c8ccd1; }
html.dark-theme .nt-theme:hover { background: rgba(255, 255, 255, .08); color: #fff; }

/* 狭い画面でも 1 行に収める */
.nt-brand, .nt-link, .nt-user { white-space: nowrap; }
@media (max-width: 480px) {
  .nt-nav-inner { gap: .75rem; padding: .4rem .75rem; }
  .nt-brand { font-size: 1.1rem; margin-right: 0; }
  .nt-link { font-size: .9rem; }
  .nt-theme { width: 34px; height: 34px; }
}