body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}
header {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 1em 0;
}
nav {
    background-color: #444;
    padding: 1em;
    position: sticky;
    top: 0;
    z-index: 1000;
}
nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
}
nav ul li {
    margin: 0 1em;
}
nav ul li a {
    color: #fff;
    text-decoration: none;
    font-weight: bold;
}
nav ul li a:hover {
    text-decoration: underline;
}
.container {
    max-width: 800px;
    margin: 2em auto;
    padding: 0 1em;
}
section {
    background: #fff;
    padding: 1.5em;
    margin-bottom: 1em;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}
h2 {
    color: #333;
}
pre {
    background: #eee;
    padding: 1em;
    border-radius: 5px;
    overflow-x: auto;
}
footer {
    text-align: center;
    padding: 1em 0;
    background-color: #333;
    color: #fff;
    position: relative;
    bottom: 0;
    width: 100%;
}
@media (max-width: 600px) {
    nav ul {
        flex-direction: column;
        text-align: center;
    }
    nav ul li {
        margin: 0.5em 0;
    }
}