body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
}

.book-container {
    display: flex;
    height: 200vh;
}

.chapter-list {
    width: 20%;
    background-color: #f0f0f0;
    padding: 20px;
    box-sizing: border-box;
    overflow-y: auto;
}

.chapter-title {
    display: block;
    padding: 10px 20px;
    background-color: #ddd;
    border: 1px solid #ccc;
    cursor: pointer;
    margin-bottom: 5px;
}

.chapter-title.active {
    background-color: #fff;
    border-right: 4px solid #007bff;
}

.chapter-title:hover {
    color: blue;
}

.main-content {
    flex: 1;
    padding: 20px;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
}

.page-title {
    margin: 0;
    margin-bottom: 20px;
    font-size: 24px;
    font-weight: bold;
    text-align: center;
}

.iframe-container {
    flex: 1;
    overflow-y: auto;
}

iframe {
    width: 100%;
    height: 100%;
    border: none;
}