/* カスタムCSS - カラフルなデザインとアニメーション */
        :root {
            --color-primary: #FF6B6B;
            --color-secondary: #4ECDC4;
            --color-accent: #FFE66D;
            --color-text: #2C3E50;
            --color-bg: #F7F9FC;
        }

        body {
            font-family: 'Zen Maru Gothic', sans-serif;
            background-color: var(--color-bg);
            color: var(--color-text);
            overflow-x: hidden;
        }

        h1, h2, h3 {
            font-family: 'Mochiy+Pop+One', sans-serif;
        }

        /* カラフルなタイトル */
        .rainbow-text {
            background: linear-gradient(45deg, #c2cc00, #eaff00, #c9cc00, #ffe100, #dab900, #b58e01, #a16300);
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
        }

        /* カラフルな見出し装飾 */
        h2 {
            border-bottom: 4px solid #4ECDC4;
            padding-bottom: 0.5rem;
            color: #2C3E50;
        }
        h2::first-letter {
            color: #c25400;
            font-size: 1.5em;
        }

        /* イス（カード）のデザイン */
        .chair-card {
            background: white;
            border-radius: 20px;
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            cursor: pointer;
            border: 2px solid #E2E8F0;
            position: relative;
            overflow: hidden;
            aspect-ratio: 3/4;
            display: flex;
            justify-content: center;
            align-items: center;
            font-size: 2rem;
            font-family: 'Mochiy+Pop+One', sans-serif;
            color: #4A5568;
            user-select: none;
        }

        .chair-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
            border-color: #4ECDC4;
        }

        .chair-card:active {
            transform: scale(0.95);
        }

        .chair-card.removed {
            opacity: 0;
            pointer-events: none;
            transform: scale(0);
        }

        /* ボタンデザイン */
        .btn-game {
            transition: transform 0.1s;
            box-shadow: 0 4px 0 rgba(0,0,0,0.2);
        }
        .btn-game:active {
            transform: translateY(4px);
            box-shadow: none;
        }

        /* シェアボタン */
        .share-btn {
            transition: opacity 0.2s;
        }
        .share-btn:hover {
            opacity: 0.8;
        }

        /* リンク */
        a {
            color: #3182CE;
            text-decoration: none;
            transition: color 0.2s;
        }
        a:hover {
            color: #2C5282;
            text-decoration: underline;
        }

        /* スマホ横向き最適化 */
        @media (orientation: landscape) and (max-height: 500px) {
            .chair-grid {
                grid-template-columns: repeat(6, 1fr) !important;
            }
            header, .share-area, .game-info {
                padding: 0.2rem !important;
            }
            .chair-card {
                aspect-ratio: auto;
                height: 60px;
                font-size: 1.5rem;
            }
        }
       
        /* 状態表示アニメーション */
        @keyframes flashRed {
            0%, 100% { background-color: white; }
            50% { background-color: #FED7D7; }
        }
        .flash-error {
            animation: flashRed 0.5s ease-in-out;
        }