body {
    font-family: "Times New Roman", Times, serif;
    background-color: #ffffff;
    color: #000000;
    line-height: 1.5;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
}

main {
    max-width: 640px;
    width: 100%;
    padding: 20px;
}

header {
    border-bottom: 1px solid #eee;
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 10px;
}

header a {
    color: #0000ee;
    text-decoration: none;
}

header a:visited {
    color: #551a8b;
}

header a:hover {
    text-decoration: underline;
}

.breadcrumbs {
    font-size: 0.9em;
    color: #666;
    margin-bottom: 20px;
}

.breadcrumbs a {
    color: #0000ee;
    text-decoration: none;
}

h1 {
    font-size: 24px;
    margin-top: 0;
}

h2 {
    font-size: 18px;
    color: #666;
    margin-bottom: 5px;
}

article {
    margin-bottom: 40px;
}

footer {
    border-top: 1px solid #eee;
    margin-top: 40px;
    padding-top: 20px;
    font-size: 0.8em;
    color: #666;
    text-align: center;
}

.toc-list {
    list-style: none;
    padding: 0;
}

.toc-list li {
    margin-bottom: 10px;
}

.toc-list a {
    text-decoration: none;
    color: #0000ee;
}

.toc-list a:hover {
    text-decoration: underline;
}

.chapter-title {
    font-weight: bold;
    margin-top: 20px;
    display: block;
}