/* ===========================================================================
   最大公約数トレーナー (gcd-trainer) - スタイルシート
   全セレクタは .gcd-trainer 配下でスコープ化（Cocoonテーマ干渉防止）
   =========================================================================== */

  /* アプリを表示領域の下端まで伸ばすため、ページ側にも高さを確保する */
  html:has(.gcd-trainer),
  body:has(.gcd-trainer) {
    height: 100%;
    overflow: hidden;
  }
  body:has(.gcd-trainer) {
    margin: 0;
    background: linear-gradient(135deg,#0ea5e9,#6366f1,#8b5cf6);
  }

  .gcd-trainer {
    /* CSS変数をラッパーに定義 */
    --primary: #3b82f6;
    --primary-dark: #1e40af;
    --success: #10b981;
    --success-dark: #047857;
    --danger: #ef4444;
    --danger-light: #fee2e2;
    --warning: #f59e0b;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
    --shadow-xl: 0 20px 25px rgba(0,0,0,0.1);
    --radius: 12px;
    --radius-lg: 16px;
    --transition: all 0.2s ease-in-out;
    
    /* 背景とパディング */
    font-family: system-ui, -apple-system, "Noto Sans JP", sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    margin: 0;
    padding: 16px;
    color: var(--gray-900);
    min-height: 100vh;
    line-height: 1.6;
  }

  .gcd-trainer * {
    box-sizing: border-box;
  }
  .gcd-trainer [hidden] { display: none !important; }

  /* 入力フィールドの見た目 */
  .gcd-trainer .section-input {
    width: 120px;
    padding: 8px 12px;
    border: 2px solid var(--gray-300);
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    background: white;
    color: var(--gray-700);
    transition: var(--transition);
  }
  .gcd-trainer .section-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
  }
  .gcd-trainer .section-input::placeholder {
    color: var(--gray-400);
    font-weight: 500;
  }

  .gcd-trainer .container {
    max-width: 1100px;
    margin: 0 auto;
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    backdrop-filter: blur(10px);
  }

  .gcd-trainer .header {
    background: linear-gradient(135deg, var(--gray-900) 0%, var(--gray-700) 100%);
    color: white;
    padding: 24px;
    position: relative;
    overflow: hidden;
  }

  .gcd-trainer .header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="50" cy="50" r="2" fill="white" opacity="0.1"/><circle cx="20" cy="30" r="1.5" fill="white" opacity="0.1"/><circle cx="80" cy="70" r="1" fill="white" opacity="0.1"/></svg>') repeat;
    pointer-events: none;
  }

  .gcd-trainer .header-content {
    position: relative;
    z-index: 1;
  }

  .gcd-trainer .title, .gcd-trainer .app-title {
    font-size: 28px;
    font-weight: 800;
    margin: 0 0 20px 0;
    display: flex;
    align-items: center;
    gap: 12px;
  }

  .gcd-trainer .title::before, .gcd-trainer .app-title::before {
    content: '🔢';
    font-size: 32px;
  }

  .gcd-trainer .controls {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 20px;
  }

  .gcd-trainer .btn {
    border: none;
    border-radius: var(--radius);
    padding: 12px 20px;
    font-weight: 600;
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 8px;
    min-width: fit-content;
    white-space: nowrap;
    position: relative;
    overflow: hidden;
  }

  .gcd-trainer .btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.5s;
  }

  .gcd-trainer .btn:hover::before {
    left: 100%;
  }

  .gcd-trainer .btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
  }

  .gcd-trainer .btn:not(:disabled):hover {
    transform: translateY(-2px);
  }

  .gcd-trainer .btn:not(:disabled):active {
    transform: translateY(0);
  }

  .gcd-trainer .btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    box-shadow: var(--shadow);
  }

  .gcd-trainer .btn-success {
    background: linear-gradient(135deg, var(--success) 0%, var(--success-dark) 100%);
    color: white;
    box-shadow: var(--shadow);
  }

  .gcd-trainer .btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.3);
  }

  .gcd-trainer .error-message {
    color: var(--danger);
    font-size: 14px;
    margin-top: 12px;
    padding: 8px 12px;
    background: var(--danger-light);
    border-radius: var(--radius);
    border-left: 4px solid var(--danger);
    display: none;
  }

  .gcd-trainer .error-message.show {
    display: block;
    animation: slideDown 0.3s ease-out;
  }

  @keyframes slideDown {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .gcd-trainer .content {
    padding: 0;
  }

  .gcd-trainer .section {
    border-bottom: 1px solid var(--gray-200);
    background: white;
    transition: var(--transition);
  }

  .gcd-trainer .section:last-child {
    border-bottom: none;
  }

  .gcd-trainer .section-header {
    padding: 20px 24px;
    background: var(--gray-50);
    border-bottom: 1px solid var(--gray-200);
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-weight: 600;
    position: sticky;
    top: 0;
    z-index: 10;
    backdrop-filter: blur(10px);
  }

  .gcd-trainer .section-header-left {
    display: flex;
    align-items: center;
    gap: 12px;
  }

  .gcd-trainer .section-btn {
    border: none;
    border-radius: var(--radius);
    padding: 8px 16px;
    font-weight: 600;
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 6px;
    background: linear-gradient(135deg, var(--success) 0%, var(--success-dark) 100%);
    color: white;
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
  }

  .gcd-trainer .section-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.5s;
  }

  .gcd-trainer .section-btn:hover::before {
    left: 100%;
  }

  .gcd-trainer .section-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
  }

  .gcd-trainer .section-btn:not(:disabled):hover {
    transform: translateY(-1px);
  }

  .gcd-trainer .section-btn:not(:disabled):active {
    transform: translateY(0);
  }

  .gcd-trainer .section-title {
    font-size: 16px;
    margin: 0;
    color: var(--gray-700);
  }

  .gcd-trainer .badge {
    font-size: 12px;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 999px;
    background: linear-gradient(135deg, var(--danger) 0%, #dc2626 100%);
    color: white;
    box-shadow: var(--shadow-sm);
    animation: pulse 2s infinite;
  }

  @keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.8; }
  }

  .gcd-trainer .divisors-container {
    padding: 24px;
    min-height: 80px;
  }

  .gcd-trainer .divisors-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    align-items: flex-start;
  }

  .gcd-trainer .chip {
    min-width: 60px;
    padding: 12px 16px;
    border-radius: var(--radius);
    font-weight: 700;
    text-align: center;
    background: var(--gray-100);
    color: var(--gray-700);
    border: 2px solid var(--gray-200);
    transition: var(--transition);
    position: relative;
    animation: chipEnter 0.4s ease-out;
  }

  @keyframes chipEnter {
    from {
      opacity: 0;
      transform: scale(0.8) translateY(20px);
    }
    to {
      opacity: 1;
      transform: scale(1) translateY(0);
    }
  }

  .gcd-trainer .chip:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
  }

  .gcd-trainer .chip.common {
    background: linear-gradient(135deg, #dbeafe 0%, #bfdbfe 100%);
    color: var(--primary-dark);
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
  }

  .gcd-trainer .chip.gcd {
    background: linear-gradient(135deg, var(--danger) 0%, #dc2626 100%);
    color: white;
    border-color: var(--danger);
    box-shadow: var(--shadow);
    position: relative;
    animation: gcdFound 0.6s ease-out;
  }

  .gcd-trainer .chip.gcd::after {
    content: 'GCD';
    position: absolute;
    top: -8px;
    right: -8px;
    background: var(--warning);
    color: white;
    font-size: 10px;
    font-weight: 800;
    padding: 4px 8px;
    border-radius: 999px;
    box-shadow: var(--shadow-sm);
  }

  @keyframes gcdFound {
    0% {
      transform: scale(1);
    }
    50% {
      transform: scale(1.2);
      box-shadow: 0 0 20px rgba(239, 68, 68, 0.5);
    }
    100% {
      transform: scale(1);
    }
  }

  .gcd-trainer .footer {
    padding: 20px 24px;
    background: var(--gray-50);
    border-top: 1px solid var(--gray-200);
    font-size: 14px;
    color: var(--gray-600);
    line-height: 1.6;
  }

  .gcd-trainer .kbd {
    font-family: 'SF Mono', Monaco, 'Cascadia Code', monospace;
    background: var(--gray-200);
    color: var(--gray-700);
    padding: 2px 8px;
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    border: 1px solid var(--gray-300);
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
  }

  .gcd-trainer .empty-state {
    text-align: center;
    color: var(--gray-400);
    font-style: italic;
    padding: 40px 20px;
  }

  /* レスポンシブデザイン */
  @media (max-width: 768px) {
    .gcd-trainer {
      padding: 8px;
    }

    .gcd-trainer .header {
      padding: 20px;
    }

    .gcd-trainer .title, .gcd-trainer .app-title {
      font-size: 24px;
    }

    .gcd-trainer .controls {
      flex-direction: column;
    }

    .gcd-trainer .btn {
      justify-content: center;
      width: 100%;
    }

    .gcd-trainer .section-header {
      flex-direction: column;
      align-items: stretch;
      gap: 12px;
    }

    .gcd-trainer .section-header-left {
      justify-content: center;
    }

    .gcd-trainer .section-btn {
      width: 100%;
      justify-content: center;
    }

    .gcd-trainer .divisors-container {
      padding: 16px;
    }

    .gcd-trainer .chip {
      min-width: 50px;
      padding: 10px 12px;
      font-size: 14px;
    }
  }

  @media (max-width: 480px) {
    .gcd-trainer .divisors-grid {
      gap: 8px;
    }

    .gcd-trainer .chip {
      min-width: 45px;
      padding: 8px 10px;
      font-size: 13px;
    }

    .gcd-trainer .section-btn {
      padding: 10px 16px;
      font-size: 12px;
    }
  }

  /* フォーカス表示の改善 */
  .gcd-trainer .btn:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
  }

  .gcd-trainer .section-input:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
  }

  /* 教育用ツールUI */
  .gcd-trainer {
    --ctu-main: #1e3a5f;
    --ctu-main-dark: #0f1e3a;
    --ctu-accent: #d4af37;
    --ctu-accent-light: #f4cf5f;
    --ctu-text: #2c3e50;
    --ctu-muted: #7f8c8d;
    --ctu-bg: linear-gradient(135deg,#0ea5e9,#6366f1,#8b5cf6);
    min-height: 0;
    height: 100dvh;
    padding: 0;
    background: var(--ctu-bg);
    color: var(--ctu-text);
    line-height: 1.4;
    overflow: hidden;
  }
  .gcd-trainer .gcd-app-shell {
    position: relative;
    width: 100%;
    max-width: none;
    height: 100%;
    margin: 0;
    border-radius: 0;
    display: flex;
    flex-direction: column;
    background: transparent;
    box-shadow: none;
    overflow: hidden;
  }
  .gcd-trainer .gcd-app-header {
    flex: 0 0 66px;
    height: 66px;
    padding: 10px 20px;
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--ctu-main);
    color: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,.18);
    overflow: visible;
    z-index: 20;
  }
  .gcd-trainer .gcd-app-header::before { display: none; }
  .gcd-trainer .app-title {
    flex: 0 0 auto;
    margin: 0;
    font-size: 19px;
    font-weight: 900;
    white-space: nowrap;
  }
  .gcd-trainer .app-title::before { display: none; }
  .gcd-trainer .header-inputs {
    flex: 1;
    min-width: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 9px;
    color: rgba(255,255,255,.84);
    font-weight: 900;
  }
  .gcd-trainer .header-inputs label {
    min-height: 42px;
    padding: 3px 5px 3px 13px;
    border-radius: 999px;
    display: flex;
    align-items: center;
    gap: 7px;
    background: rgba(255,255,255,.13);
  }
  .gcd-trainer .section-input {
    width: 72px;
    height: 36px;
    padding: 4px 8px;
    border: 0;
    border-radius: 999px;
    color: var(--ctu-main-dark);
    font-size: 18px;
    font-weight: 900;
    text-align: center;
  }
  .gcd-trainer .section-input:focus {
    border: 0;
    outline: 4px solid var(--ctu-accent-light);
    box-shadow: none;
  }
  .gcd-trainer .fullscreen-btn {
    flex: 0 0 auto;
    width: 42px;
    height: 42px;
    padding: 0;
    border: 0;
    border-radius: 50%;
    display: grid;
    place-items: center;
    background: rgba(255,255,255,.14);
    color: #fff;
    font-size: 23px;
    cursor: pointer;
  }
  .gcd-trainer .gcd-app-content {
    flex: 1 1 0%;
    width: 100%;
    height: auto;
    max-height: none;
    min-height: 0;
    padding: 18px 90px 24px 18px;
    display: flex;
    flex-direction: column;
    overflow: auto;
  }
  .gcd-trainer .prompt {
    flex: 0 0 auto;
    margin: 0 auto 15px;
    padding: 8px 20px;
    border-radius: 999px;
    background: rgba(15,30,58,.25);
    color: #fff;
    font-size: clamp(16px,2vw,22px);
    font-weight: 900;
    text-align: center;
  }
  .gcd-trainer .error-message {
    position: absolute;
    top: 76px;
    left: 50%;
    z-index: 60;
    width: min(420px,calc(100% - 100px));
    margin: 0;
    transform: translateX(-50%);
    text-align: center;
    box-shadow: 0 5px 18px rgba(0,0,0,.16);
  }
  .gcd-trainer .compare-grid {
    flex: 1;
    min-height: 0;
    display: flex;
    flex-direction: column;
    gap: 18px;
  }
  .gcd-trainer .compare-grid.has-c .section { min-height: 150px; }
  .gcd-trainer .section {
    flex: 1 1 0%;
    min-height: 190px;
    border: 0;
    border-top: 4px solid var(--layer-color);
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    background: #fff;
    box-shadow: 0 8px 24px rgba(0,0,0,.16);
    overflow: hidden;
  }
  .gcd-trainer .section-a { --layer-color:#2d6ca2; }
  .gcd-trainer .section-b { --layer-color:#7752a9; }
  .gcd-trainer .section-c { --layer-color:#16836b; }
  .gcd-trainer .section-header {
    position: static;
    flex: 0 0 auto;
    min-height: 68px;
    padding: 12px 18px;
    border: 0;
    border-bottom: 1px solid #e5edf4;
    flex-direction: row;
    gap: 10px;
    background: #fff;
  }
  .gcd-trainer .section-title {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--ctu-main);
    font-size: 19px;
    font-weight: 900;
  }
  .gcd-trainer .section-letter {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    display: grid;
    place-items: center;
    background: var(--layer-color);
    color: #fff;
  }
  .gcd-trainer .badge {
    display: inline-block;
    padding: 7px 12px;
    background: #c94b4b;
    font-size: 13px;
    animation: gcdFound .6s ease-out;
  }
  .gcd-trainer .divisors-container {
    flex: 1;
    min-height: 110px;
    padding: 20px;
    overflow: auto;
  }
  .gcd-trainer .divisors-grid {
    gap: 11px;
    align-content: flex-start;
  }
  .gcd-trainer .chip {
    min-width: 68px;
    padding: 12px 14px;
    border: 2px solid #dce5ee;
    border-radius: 12px;
    background: #f4f7fa;
    color: var(--ctu-text);
    font-size: 18px;
    box-shadow: none;
  }
  .gcd-trainer .chip.common {
    border-color: #3b82f6;
    background: #dbeafe;
    color: #1e40af;
  }
  .gcd-trainer .chip.gcd {
    border-color: #c94b4b;
    background: #c94b4b;
    color: #fff;
  }
  .gcd-trainer .chip.gcd::after {
    content: '最大';
    top: -9px;
    right: -8px;
    background: var(--ctu-accent);
    color: var(--ctu-main-dark);
  }
  .gcd-trainer .empty-state {
    width: 100%;
    padding: 20px 10px;
    color: var(--ctu-muted);
    font-style: normal;
    font-size: 17px;
    font-weight: 700;
  }
  .gcd-trainer .toolbar {
    position: absolute;
    right: 20px;
    bottom: 20px;
    z-index: 50;
    display: flex;
    flex-direction: column;
    gap: 11px;
  }
  .gcd-trainer .tool {
    width: 56px;
    height: 56px;
    padding: 0;
    border: 0;
    border-radius: 50%;
    display: grid;
    place-items: center;
    background: #fff;
    color: var(--ctu-main);
    box-shadow: 0 4px 14px rgba(0,0,0,.24);
    font-size: 23px;
    font-weight: 900;
    cursor: pointer;
  }
  .gcd-trainer .tool-a { color:#2d6ca2; }
  .gcd-trainer .tool-b { color:#7752a9; }
  .gcd-trainer .tool-settings { color:var(--ctu-main); }
  .gcd-trainer .tool-auto { background:var(--ctu-main); color:#fff; }
  .gcd-trainer .tool-primary { background:var(--ctu-accent); color:var(--ctu-main-dark); }
  .gcd-trainer .tool-danger { color:#b43e3e; }
  .gcd-trainer .tool:hover:not(:disabled) { transform: translateY(-2px); }
  .gcd-trainer .tool:disabled { opacity:.42; cursor:not-allowed; }
  .gcd-trainer .tool:focus-visible,.gcd-trainer .fullscreen-btn:focus-visible {
    outline:4px solid var(--ctu-accent-light);
    outline-offset:2px;
  }
  .gcd-trainer:fullscreen { width:100vw; height:100dvh; }
  .gcd-trainer .current-pair {
    flex:1;
    display:flex;
    justify-content:center;
    align-items:center;
    gap:10px;
    color:rgba(255,255,255,.78);
    font-weight:900;
  }
  .gcd-trainer .current-pair strong {
    min-width:46px;
    padding:5px 12px;
    border-radius:999px;
    background:rgba(255,255,255,.15);
    color:#fff;
    font-size:20px;
    text-align:center;
  }
  .gcd-trainer .section-actions { display:flex; align-items:center; gap:9px; }
  .gcd-trainer .card-next {
    min-width:58px;
    min-height:44px;
    padding:7px 12px;
    border:0;
    border-radius:12px;
    background:var(--layer-color);
    color:#fff;
    font-size:14px;
    font-weight:900;
    cursor:pointer;
  }
  .gcd-trainer .card-next:disabled { opacity:.38; cursor:not-allowed; }
  .gcd-trainer .card-next:focus-visible { outline:4px solid var(--ctu-accent-light); outline-offset:2px; }
  .gcd-trainer .number-modal {
    position:absolute;
    inset:0;
    z-index:100;
    padding:20px;
    display:grid;
    place-items:center;
    background:rgba(15,30,58,.72);
    backdrop-filter:blur(5px);
  }
  .gcd-trainer .number-modal[hidden] { display:none; }
  .gcd-trainer .number-dialog {
    width:min(790px,100%);
    padding:clamp(22px,4vw,38px);
    border-top:5px solid var(--ctu-accent);
    border-radius:20px;
    background:#fff;
    box-shadow:0 18px 50px rgba(0,0,0,.28);
    text-align:center;
  }
  .gcd-trainer .number-dialog h2 {
    margin:0 0 25px;
    color:var(--ctu-main);
    font-size:clamp(22px,3vw,30px);
    font-weight:900;
  }
  .gcd-trainer .number-pickers { display:flex; justify-content:center; align-items:center; gap:20px; }
  .gcd-trainer .number-picker {
    display:grid;
    grid-template-columns:44px 88px 44px;
    grid-template-areas:"label label label" "minus input plus";
    gap:9px;
    align-items:center;
  }
  .gcd-trainer .picker-label { grid-area:label; justify-self:center; width:42px; height:42px; border-radius:50%; display:grid; place-items:center; color:#fff; font-size:19px; font-weight:900; }
  .gcd-trainer .picker-a { background:#2d6ca2; }
  .gcd-trainer .picker-b { background:#7752a9; }
  .gcd-trainer .picker-c { background:#16836b; }
  .gcd-trainer .adjust {
    width:44px;
    height:44px;
    padding:0;
    border:0;
    border-radius:50%;
    background:#edf2f7;
    color:var(--ctu-main);
    font-size:25px;
    font-weight:900;
    cursor:pointer;
  }
  .gcd-trainer .adjust[data-change="-1"] { grid-area:minus; }
  .gcd-trainer .adjust[data-change="1"] { grid-area:plus; }
  .gcd-trainer .number-input {
    grid-area:input;
    width:88px;
    height:70px;
    padding:5px;
    border:3px solid #dce5ee;
    border-radius:15px;
    color:var(--ctu-main-dark);
    font-size:34px;
    font-weight:900;
    text-align:center;
  }
  .gcd-trainer .number-input:focus { outline:4px solid var(--ctu-accent-light); border-color:var(--ctu-main); }
  .gcd-trainer .picker-and { margin-top:47px; color:var(--ctu-muted); font-size:18px; font-weight:900; }
  .gcd-trainer .preset-list { margin:24px 0 18px; display:flex; flex-wrap:wrap; justify-content:center; gap:8px; }
  .gcd-trainer .add-c-btn {
    min-height:44px;
    margin-top:18px;
    padding:8px 18px;
    border:2px dashed #9fb0c2;
    border-radius:999px;
    background:#f7f9fb;
    color:var(--ctu-main);
    font-weight:900;
    cursor:pointer;
  }
  .gcd-trainer .add-c-btn.is-active { border-style:solid; border-color:#d9a6a6; background:#fff4f4; color:#a33b3b; }
  .gcd-trainer .preset-list button {
    min-height:44px;
    padding:8px 15px;
    border:2px solid #dce5ee;
    border-radius:999px;
    background:#fff;
    color:var(--ctu-main);
    font-weight:900;
    cursor:pointer;
  }
  .gcd-trainer .preset-list button:hover { border-color:var(--ctu-accent); background:#fff9dc; }
  .gcd-trainer .modal-error { min-height:22px; margin-bottom:8px; color:#b43e3e; font-weight:800; }
  .gcd-trainer .start-btn {
    min-width:200px;
    min-height:54px;
    padding:12px 28px;
    border:0;
    border-radius:999px;
    background:var(--ctu-accent);
    color:var(--ctu-main-dark);
    box-shadow:0 5px 14px rgba(15,30,58,.18);
    font-size:19px;
    font-weight:900;
    cursor:pointer;
  }
  @media (max-width: 760px) {
    .gcd-trainer { min-height:0; height:100dvh; }
    .gcd-trainer .gcd-app-header { flex-basis:58px; height:58px; padding:8px 9px; gap:7px; }
    .gcd-trainer .app-title { font-size:14px; }
    .gcd-trainer .current-pair { gap:5px; }
    .gcd-trainer .current-pair strong { min-width:36px; padding:4px 8px; font-size:16px; }
    .gcd-trainer .fullscreen-btn { width:38px; height:38px; }
    .gcd-trainer .gcd-app-content { padding:10px 72px 16px 10px; }
    .gcd-trainer .prompt { margin-bottom:9px; padding:6px 12px; font-size:14px; }
    .gcd-trainer .compare-grid,.gcd-trainer .compare-grid.has-c { gap:10px; }
    .gcd-trainer .section,.gcd-trainer .compare-grid.has-c .section { min-height:145px; }
    .gcd-trainer .divisors-container { min-height:82px; }
    .gcd-trainer .section-header { min-height:48px; padding:7px 10px; }
    .gcd-trainer .section-title { font-size:15px; }
    .gcd-trainer .section-letter { width:32px; height:32px; }
    .gcd-trainer .badge { padding:5px 8px; font-size:11px; }
    .gcd-trainer .divisors-container { padding:11px; }
    .gcd-trainer .divisors-grid { gap:7px; }
    .gcd-trainer .chip { min-width:51px; padding:7px 9px; font-size:14px; }
    .gcd-trainer .empty-state { padding:20px 5px; font-size:14px; }
    .gcd-trainer .toolbar { right:12px; bottom:12px; gap:8px; }
    .gcd-trainer .tool { width:50px; height:50px; font-size:20px; }
    .gcd-trainer .number-modal { padding:10px; }
    .gcd-trainer .number-dialog { padding:20px 12px; }
    .gcd-trainer .number-dialog h2 { margin-bottom:17px; }
    .gcd-trainer .number-pickers { gap:8px; }
    .gcd-trainer .number-pickers.has-c { gap:4px; flex-wrap:wrap; }
    .gcd-trainer .number-picker { grid-template-columns:40px 66px 40px; gap:6px; }
    .gcd-trainer .adjust { width:40px; height:40px; }
    .gcd-trainer .number-input { width:66px; height:58px; font-size:28px; }
    .gcd-trainer .number-pickers.has-c .number-picker { grid-template-columns:34px 56px 34px; gap:4px; }
    .gcd-trainer .number-pickers.has-c .adjust { width:34px; height:34px; font-size:20px; }
    .gcd-trainer .number-pickers.has-c .number-input { width:56px; height:52px; font-size:24px; }
    .gcd-trainer .picker-and { margin-top:42px; font-size:15px; }
    .gcd-trainer .preset-list { margin:17px 0 10px; }
    .gcd-trainer .preset-list button { padding:7px 11px; font-size:13px; }
    .gcd-trainer .card-next { min-width:52px; min-height:40px; padding:5px 9px; }
  }
  @media (prefers-reduced-motion:reduce) {
    .gcd-trainer * { animation-duration:.01ms !important; transition-duration:.01ms !important; }
  }

  /* 修正: WordPress管理者バー(admin bar)表示時に画面の高さがズレる問題を補正
     admin bar は position:fixed の別要素のため 100dvh には含まれず、
     ログイン中の教員・管理者が確認すると下端が admin bar の高さ分はみ出していた */
  body.admin-bar .gcd-trainer {
    height: calc(100dvh - 32px);
  }
  @media screen and (max-width: 782px) {
    body.admin-bar .gcd-trainer {
      height: calc(100dvh - 46px);
    }
  }
  @media (max-width: 760px) {
    body.admin-bar .gcd-trainer {
      min-height: 0;
      height: calc(100dvh - 46px);
    }
  }

  /* 修正: 一部ブラウザ(古いSafari等)でdvh未対応の場合のフォールバック */
  @supports not (height: 100dvh) {
    .gcd-trainer {
      height: 100vh;
    }
    @media (max-width: 760px) {
      .gcd-trainer { height: 100vh; }
    }
  }