body {
            font-family: Arial, sans-serif;
            background-color: #2e3440;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            margin: 0;
            padding: 20px;
            box-sizing: border-box;
        }

        .main-title {
            color: #eceff4;
            margin-bottom: 10px;
            text-align: center;
        }

        .settings {
            color: #eceff4;
            margin-bottom: 20px;
            font-size: 16px;
        }

        .settings select {
            padding: 5px;
            font-size: 16px;
            border-radius: 5px;
            margin-left: 10px;
        }

        .quiz-container {
            background: #81a1c1;
            padding: 30px;
            border-radius: 10px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
            width: 100%;
            max-width: 500px;
            box-sizing: border-box;
            margin-bottom: 20px;
        }

        .progress-container {
            width: 100%;
            background-color: #eef2f5;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 10px;
            overflow: hidden;
        }

        .progress-bar {
            height: 100%;
            background-color: #4CAF50;
            width: 0%;
            transition: width 0.3s ease;
        }

        .status-text {
            font-size: 14px;
            color: #666;
            margin-bottom: 20px;
            text-align: right;
        }

        h2 {
            margin-top: 0;
            color: #333;
        }

        .btn-grid {
            display: grid;
            gap: 15px;
            margin: 20px 0;
        }

        .btn {
            background-color: #eef2f5;
            border: 2px solid #d1d9e6;
            padding: 15px;
            border-radius: 8px;
            font-size: 16px;
            cursor: pointer;
            transition: background-color 0.2s, border-color 0.2s;
            text-align: left;
        }

        .btn:hover:not(:disabled) {
            background-color: #d1d9e6;
        }

        .btn:disabled {
            cursor: not-allowed;
        }

        .correct {
            background-color: #4CAF50 !important;
            color: white;
            border-color: #4CAF50 !important;
        }

        .wrong {
            background-color: #f44336 !important;
            color: white;
            border-color: #f44336 !important;
        }

        .next-btn {
            background-color: #007BFF;
            color: white;
            border: none;
            padding: 12px 20px;
            border-radius: 5px;
            font-size: 16px;
            cursor: pointer;
            display: block;
            width: 100%;
            box-sizing: border-box;
        }

        .next-btn:hover {
            background-color: #0056b3;
        }

        .hide {
            display: none;
        }

        .video-container {
            width: 100%;
            max-width: 500px;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
            background: #000;
        }

        iframe {
            display: block;
            width: 100%;
            height: 281px;
            border: none;
        }