body {
            padding: 20px;
        }
        .book-item {
            margin-bottom: 10px;
        }
        h4 {
            text-align: center;
        }
        details {
            border: 1px solid #aaa;
            border-radius: 4px;
            padding: 0.5em 0.5em 0;
        }
        summary {
            font-weight: bold;
            margin: -0.5em -0.5em 0;
            padding: 0.5em;
        }
        details[open] {
            padding: 0.5em;
        }
        details[open] summary {
            border-bottom: 1px solid #aaa;
            margin-bottom: 0.5em;
        }