/* ==========================================================================
       ヘッダー ＆ 右上側・横書きナビゲーションシステム
       ========================================================================== */
    header {
      background-color: rgba(255, 255, 255, 0.75);
      backdrop-filter: blur(20px) saturate(180%);
      -webkit-backdrop-filter: blur(20px) saturate(180%);
      padding: 0.8rem 1.5rem;
      position: sticky;
      top: 0;
      z-index: 1000;
      border-bottom: 1px solid rgba(44, 58, 78, 0.08);
      transition: var(--transition-smooth);
    }
    .header-content {
      max-width: 1300px;
      margin: 0 auto;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .header-title h1 {
      font-size: 1.3rem;
      margin: 0;
      font-weight: 900;
      color: var(--color-primary);
      letter-spacing: 0.1em;
    }
    .header-title p {
      margin: 0;
      font-size: 0.7rem;
      font-weight: 700;
      color: var(--color-key);
      text-transform: uppercase;
    }

    /* PC・タブレット用：右上側の常時横書きナビゲーション */
    .pc-nav {
      display: none;
    }
    .pc-nav-links {
      display: flex;
      list-style: none;
      margin: 0;
      padding: 0;
      gap: 2.2rem;
    }
    .pc-nav-links a {
      color: var(--color-primary);
      text-decoration: none;
      font-weight: 800;
      font-size: 0.9rem;
      position: relative;
      padding: 0.4rem 0;
      transition: var(--transition-smooth);
    }
    .pc-nav-links a::after {
      content: "";
      position: absolute;
      bottom: 0; left: 0;
      width: 0; height: 2px;
      background-color: var(--color-key);
      transition: var(--transition-smooth);
    }
    .pc-nav-links a:hover {
      color: var(--color-key);
    }
    .pc-nav-links a:hover::after {
      width: 100%;
    }
    
    /* 🟢 【改善】現在位置を示すアクティブステート（迷子防止） */
    .pc-nav-links a.active, .nav-links a.active {
      color: var(--color-key) !important;
      font-weight: 900;
    }
    .pc-nav-links a.active::after {
      width: 100%;
    }

    /* スマホ用ハンバーガーツマミ */
    .menu-trigger {
      background: none;
      border: none;
      width: 44px;
      height: 44px;
      position: relative;
      cursor: pointer;
      z-index: 1100;
      padding: 0;
      box-shadow: none;
      display: flex;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 6px;
    }
    .menu-trigger span {
      display: block;
      width: 24px;
      height: 2px;
      background-color: var(--color-primary);
      transition: var(--transition-bounce);
      transform-origin: center;
    }
    .menu-trigger.is-active span:nth-child(1) {
      transform: translateY(8px) rotate(45deg);
    }
    .menu-trigger.is-active span:nth-child(2) {
      opacity: 0;
    }
    .menu-trigger.is-active span:nth-child(3) {
      transform: translateY(-8px) rotate(-45deg);
    }

    /* スマホ用：右上側にコンパクトに現れるナビメニュー */
    .fullscreen-nav {
      position: absolute;
      top: 100%;
      right: 1.5rem;
      width: calc(100% - 3rem);
      max-width: 320px;
      height: auto;
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      z-index: 1050;
      border-radius: 16px;
      padding: 1.25rem;
      box-shadow: var(--shadow-lg);
      border: 1px solid rgba(44, 58, 78, 0.08);
      opacity: 0;
      pointer-events: none;
      transform: translateY(-10px) scale(0.95);
    }
    .fullscreen-nav.is-open {
      pointer-events: auto;
    }
    .nav-links {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 0.75rem;
      list-style: none;
      padding: 0;
      margin: 0;
      text-align: center;
    }
    .nav-links a {
      color: var(--color-primary);
      font-size: 0.85rem;
      font-weight: 800;
      text-decoration: none;
      padding: 0.8rem 0.5rem;
      display: block;
      background: rgba(44, 58, 78, 0.03);
      border-radius: 10px;
      transition: var(--transition-smooth);
    }
    .nav-links a:hover {
      color: var(--color-white);
      background-color: var(--color-key);
    }

    @media (min-width: 768px) {
      .pc-nav { display: block; }
      .menu-trigger { display: none; }
      .fullscreen-nav { display: none !important; }
    }

        /* ==========================================================================
       🌐 フッター ＆ サイトマップ（文字サイズ階層を完全に再整理）
       ========================================================================== */
    footer {
      background-color: var(--color-primary-dark);
      color: rgba(255, 255, 255, 0.8);
      padding: 5rem 1.5rem 3rem;
      border-top: 1px solid rgba(255, 255, 255, 0.06);
    }
    .footer-container {
      max-width: 1300px;
      margin: 0 auto;
    }
    .sitemap-group {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
      gap: 3rem;
      margin-bottom: 4rem;
    }
    
    /* 🟢 【改善】h5(大見出し)・リンク本文・コピーライトのジャンプ率（階層構造）を美しく整理 */
    .sitemap-item h5 {
      color: var(--color-white);
      font-size: 1.05rem; /* 見出しをパッと際立たせる */
      font-weight: 800;
      margin-bottom: 1.5rem;
      letter-spacing: 0.05em;
    }
    .sitemap-links {
      display: flex;
      flex-direction: column;
      gap: 0.9rem;
    }
    .sitemap-links a {
      color: rgba(255, 255, 255, 0.65);
      text-decoration: none;
      font-size: 0.9rem; /* 本文として最も読みやすい絶妙なサイズ */
      font-weight: 500;
      transition: var(--transition-smooth);
    }
    .sitemap-links a:hover {
      color: var(--color-key);
      transform: translateX(4px);
    }

    .footer-bottom {
      border-top: 1px solid rgba(255, 255, 255, 0.08);
      padding-top: 2.5rem;
      display: flex;
      flex-direction: column;
      gap: 1.5rem;
    }
    @media (min-width: 768px) {
      .footer-bottom {
        flex-direction: row;
        justify-content: space-between;
        align-items: flex-end;
      }
    }
    .footer-info-block p {
      margin: 0 0 0.4rem 0;
      font-size: 0.9rem;
      color: var(--color-white);
    }
    .footer-info-block .school-name {
      font-size: 1.1rem;
      font-weight: 800;
      color: var(--color-white);
    }
    .footer-info-block a {
      color: var(--color-key);
      text-decoration: none;
    }
    
    .copyright {
      font-size: 0.75rem; /* コピーライトは最も小さく静かに配置 */
      color: rgba(255, 255, 255, 0.645);
      margin: 0;
    }