body {
    font-family: Arial, sans-serif;
    padding: 20px;
}

ul {
    list-style-type: none;
    padding: 0;
}

ul.breadcrumbs {
    display: flex;
    flex-wrap: wrap;
}

ul.breadcrumbs li {
    margin-right: 10px;
}

.chapter-box {
    display: inline-block;
    padding: 10px;
    margin: 5px;
    background-color: #f0f0f0;
    text-align: center;
    width: 50px;
    height: 50px;
    line-height: 30px;
    border-radius: 5px;
}

.chapters-grid {
    display: flex;
    flex-wrap: wrap;
}