body {
            font-family: Arial, sans-serif;
            max-width: 1000px;
            margin: 0 auto;
            padding: 20px;
            line-height: 1.6;
        }
        h1 {
            color: #2c3e50;
            text-align: center;
            margin-bottom: 30px;
        }
        .toc {
            background-color: #f8f9fa;
            padding: 20px;
            border-radius: 5px;
            margin-bottom: 30px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
        }
        .toc h2 {
            color: #2c3e50;
            border-bottom: 2px solid #3498db;
            padding-bottom: 10px;
            margin-top: 0;
        }
        .toc ul {
            list-style-type: none;
            padding: 0;
        }
        .toc li {
            margin: 10px 0;
            padding: 8px 0;
            border-bottom: 1px solid #eee;
        }
        .toc a {
            color: #2980b9;
            text-decoration: none;
            font-weight: bold;
            display: block;
            padding: 5px 10px;
            transition: all 0.3s;
        }
        .toc a:hover {
            background-color: #e1f5fe;
            color: #0277bd;
            border-radius: 3px;
        }
        .quiz-section {
            display: none;
            margin-bottom: 40px;
            padding: 20px;
            background-color: #fff;
            border-radius: 5px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }
        .quiz-section h2 {
            color: #2c3e50;
            border-bottom: 2px solid #3498db;
            padding-bottom: 10px;
        }
        .question {
            margin-bottom: 20px;
            padding: 15px;
            background-color: #f5f5f5;
            border-radius: 5px;
        }
        .options {
            margin-left: 20px;
        }
        .option {
            margin: 10px 0;
        }
        button {
            padding: 10px 15px;
            background-color: #4CAF50;
            color: white;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            font-size: 16px;
        }
        button:hover {
            background-color: #45a049;
        }
        .result {
            margin-top: 20px;
            padding: 15px;
            border-radius: 4px;
            display: none;
        }
        .correct {
            background-color: #dff0d8;
            color: #3c763d;
            border-left: 4px solid #3c763d;
        }
        .incorrect {
            background-color: #f2dede;
            color: #a94442;
            border-left: 4px solid #a94442;
        }
        .correct-answer {
            font-weight: bold;
            margin: 10px 0;
            padding: 8px;
            background-color: #e7f4ff;
            border-radius: 4px;
        }
        .explanation {
            margin-top: 10px;
            padding: 10px;
            background-color: #f8f9fa;
            border-left: 4px solid #3498db;
            border-radius: 0 0 4px 4px;
        }
        .back-to-toc {
            display: block;
            margin-top: 20px;
            text-align: center;
            color: #3498db;
            text-decoration: none;
            font-weight: bold;
            padding: 10px;
            border: 1px solid #3498db;
            border-radius: 4px;
        }
        .back-to-toc:hover {
            background-color: #e1f5fe;
            text-decoration: none;
        }