* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 20px;
        }

        .game-container {
            background: rgba(255, 255, 255, 0.95);
            border-radius: 20px;
            padding: 40px;
            box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
            text-align: center;
            max-width: 500px;
            width: 100%;
        }

        h1 {
            color: #333;
            margin-bottom: 30px;
            font-size: 36px;
        }

        .mode-selection {
            margin-bottom: 30px;
        }

        .mode-selection h2 {
            color: #555;
            margin-bottom: 20px;
            font-size: 22px;
        }

        .mode-buttons {
            display: flex;
            gap: 15px;
            justify-content: center;
            flex-wrap: wrap;
        }

        .mode-btn {
            padding: 15px 30px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            border-radius: 12px;
            font-size: 18px;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.2s ease, box-shadow 0.2s ease;
            box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
        }

        .mode-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
        }

        .mode-btn:active {
            transform: translateY(0);
        }

        .game-info {
            margin-bottom: 25px;
            font-size: 20px;
            color: #555;
            font-weight: 600;
            min-height: 30px;
        }

        .game-info.highlight {
            color: #667eea;
            animation: pulse 0.5s ease;
        }

        @keyframes pulse {
            0%, 100% { transform: scale(1); }
            50% { transform: scale(1.05); }
        }

        .board {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 10px;
            margin: 0 auto 30px;
            max-width: 400px;
        }

        .cell {
            aspect-ratio: 1;
            background: white;
            border: 3px solid #667eea;
            border-radius: 12px;
            font-size: 48px;
            font-weight: bold;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: all 0.3s ease;
            color: #333;
        }

        .cell:hover:not(.taken) {
            background: #f0f0f0;
            transform: scale(1.05);
            box-shadow: 0 4px 15px rgba(102, 126, 234, 0.2);
        }

        .cell.taken {
            cursor: not-allowed;
        }

        .cell.x {
            color: #667eea;
        }

        .cell.o {
            color: #764ba2;
        }

        .cell.winner {
            background: #ffd700;
            animation: winPulse 0.6s ease infinite;
        }

        @keyframes winPulse {
            0%, 100% { transform: scale(1); }
            50% { transform: scale(1.1); }
        }

        .controls {
            display: flex;
            gap: 15px;
            justify-content: center;
            flex-wrap: wrap;
        }

        .btn {
            padding: 12px 24px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.2s ease;
        }

        .btn:hover {
            transform: scale(1.05);
        }

        .btn.secondary {
            background: #888;
        }

        .hidden {
            display: none !important;
        }

        .score-board {
            margin-bottom: 20px;
            display: flex;
            justify-content: space-around;
            padding: 15px;
            background: rgba(102, 126, 234, 0.1);
            border-radius: 12px;
        }

        .score-item {
            text-align: center;
        }

        .score-label {
            font-size: 14px;
            color: #666;
            margin-bottom: 5px;
        }

        .score-value {
            font-size: 24px;
            font-weight: bold;
            color: #667eea;
        }

        @media (max-width: 480px) {
            .game-container {
                padding: 20px;
            }

            h1 {
                font-size: 28px;
                margin-bottom: 20px;
            }

            .mode-selection h2 {
                font-size: 18px;
            }

            .mode-btn {
                padding: 12px 20px;
                font-size: 16px;
            }

            .cell {
                font-size: 36px;
            }

            .game-info {
                font-size: 18px;
            }

            .btn {
                padding: 10px 20px;
                font-size: 14px;
            }
        }