/* =========================================================================
   Layout — ヘッダー・ページの見出し・節の見出し・学生募集の枠・フッター
   ========================================================================= */

/* ---------- Header ---------- */

.site-header { position: relative; z-index: 50; background: var(--color-bg); }

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  padding-block: 26px 22px;
}

/* 研究室名（文字だけのロゴ）。サイト設定で、上に小さく所属を添えることもできる */
.logo {
  display: grid;
  color: var(--color-heading);
  text-decoration: none;
}
.logo:hover { color: var(--color-heading); }
.logo__org { color: var(--color-subtle); font-size: 0.75rem; letter-spacing: 0.06em; line-height: 1.6; }
.logo__name { font-size: 1.5625rem; font-weight: 700; letter-spacing: 0.12em; line-height: 1.4; white-space: nowrap; }
.logo__name:lang(en) { letter-spacing: 0.02em; }

.site-nav { display: flex; align-items: center; gap: 26px; }
.site-nav__list { display: flex; align-items: center; gap: 26px; }
.site-nav__link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--color-ink-soft);
  font-size: 0.9375rem;
  text-decoration: none;
  white-space: nowrap;
}
.site-nav__link:hover { color: var(--color-primary); text-decoration: underline; text-decoration-thickness: 1px; }
.site-nav__link[aria-current="page"] { color: var(--color-primary); text-decoration: underline; text-decoration-thickness: 2px; text-underline-offset: 0.5em; }

/* もう一方の言語へのリンク（区切りの線の右に置く） */
.lang-link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding-left: 20px;
  border-left: 1px solid var(--color-rule);
  color: var(--color-muted);
  font-size: 0.875rem;
  text-decoration: none;
  white-space: nowrap;
}
.lang-link:hover { color: var(--color-primary); text-decoration: underline; }

.nav-toggle {
  display: none;
  min-height: 40px;
  padding: 0 14px;
  border: 1px solid #c8c8c8;
  border-radius: var(--radius);
  background: var(--color-bg);
  color: var(--color-ink);
  font-size: 0.875rem;
}
.nav-toggle__close { display: none; }
.nav-toggle[aria-expanded="true"] .nav-toggle__open { display: none; }
.nav-toggle[aria-expanded="true"] .nav-toggle__close { display: inline; }

@media (max-width: 1080px) {
  .site-nav, .site-nav__list { gap: 20px; }
}

@media (max-width: 960px) {
  .site-header__inner { padding-block: 16px 14px; }
  .logo__name { font-size: 1.3125rem; }
  .nav-toggle { display: inline-flex; align-items: center; }

  /* メニューはヘッダーのすぐ下に開く */
  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 4px var(--gutter) 28px;
    background: var(--color-bg);
    border-bottom: var(--rule);
  }
  .site-nav.is-open { display: flex; }
  .site-nav__list { flex-direction: column; align-items: stretch; gap: 0; border-top: var(--hairline); }
  .site-nav__list li { border-bottom: var(--hairline); }
  .site-nav__link { display: flex; min-height: 56px; color: var(--color-heading); font-size: 1.0625rem; }
  .site-nav__link[aria-current="page"] { text-underline-offset: 0.35em; }
  .lang-link { align-self: flex-start; margin-top: 14px; padding-left: 0; border-left: 0; font-size: 0.9375rem; }
}

/* ---------- Main ---------- */

.site-main { display: block; }

/* ---------- 下層ページの見出し ---------- */

.page-head { padding-top: 8px; }

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  color: var(--color-subtle);
  font-size: var(--text-sm);
}
.breadcrumbs a { color: var(--color-subtle); text-decoration: none; }
.breadcrumbs a:hover { color: var(--color-primary); text-decoration: underline; }
.breadcrumbs li + li::before { content: "/"; margin-right: 6px; color: #b5b5b5; }

.page-title {
  margin-top: 28px;
  font-size: var(--text-2xl);
  line-height: 1.55;
  letter-spacing: 0.08em;
}
.page-lead { margin-top: 14px; max-width: 40em; color: var(--color-ink-soft); }

/* 見出しのすぐ後の本文 */
.page-head + .section { padding-top: 56px; }

/* ---------- 節（ページ内のまとまり） ---------- */

.section { padding-top: var(--section-space); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 4px 20px;
  margin-bottom: 24px;
}
.section-title { font-size: var(--text-xl); letter-spacing: 0.08em; line-height: 1.5; }
.section-head__link { font-size: var(--text-md); white-space: nowrap; }

/* ページ内の小見出し（研究テーマの詳細・プロフィールなど） */
.subhead { margin-bottom: 16px; font-size: var(--text-lg); letter-spacing: 0.06em; }

/* ---------- 学生募集の枠 ---------- */

.recruit-box {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 40px;
  align-items: center;
  padding: 44px 52px;
  border: var(--rule);
  border-radius: var(--radius-panel);
}
.recruit-box__title { font-size: var(--text-xl); letter-spacing: 0.08em; }
.recruit-box__body { margin-top: 10px; max-width: 40em; color: var(--color-ink-soft); }
.recruit-box__links { display: grid; gap: 8px; font-size: 0.9375rem; white-space: nowrap; }

@media (max-width: 760px) {
  .recruit-box { grid-template-columns: 1fr; gap: 18px; padding: 28px 22px; }
  .recruit-box__links { white-space: normal; }
}

/* ---------- Footer ---------- */

.site-footer {
  margin-top: var(--section-space);
  padding-block: 48px 28px;
  background: var(--color-surface);
  color: #555555;
  font-size: var(--text-md);
}
.site-footer a { color: var(--color-ink-soft); text-decoration: none; }
.site-footer a:hover { color: var(--color-primary); text-decoration: underline; }

.site-footer__cols { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 40px; }
.site-footer__name { margin-bottom: 6px; color: var(--color-heading); font-size: 1.0625rem; font-weight: 700; letter-spacing: 0.1em; }
.site-footer__name:lang(en) { letter-spacing: 0.02em; }
.site-footer__contact { margin-top: 8px; }
.site-footer .site-footer__contact a { color: var(--color-primary); text-decoration: underline; }
.site-footer__heading { margin-bottom: 6px; color: var(--color-subtle); font-size: var(--text-sm); font-weight: 700; letter-spacing: 0.06em; }
.site-footer__list li { line-height: 2; }

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
  margin-top: 36px;
  padding-top: 14px;
  border-top: 1px solid #e0e2e0;
  color: var(--color-subtle);
  font-size: var(--text-sm);
}
.site-footer__bottom small { margin-right: auto; font-size: inherit; }
.site-footer .site-footer__bottom a { color: var(--color-subtle); }

@media (max-width: 760px) {
  .site-footer__cols { grid-template-columns: 1fr 1fr; gap: 28px 20px; }
  .site-footer__about { grid-column: 1 / -1; }
}