body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    background: #333;
    color: #fff;
    padding: 1em 0;
    text-align: center;
}

nav {
    margin-top: 10px;
}

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

nav ul li {
    display: inline;
    margin: 0 10px;
}

nav ul li a {
    color: #fff;
    text-decoration: none;
    padding: 5px 10px;
}

nav ul li a:hover {
    background: #555;
    border-radius: 5px;
}

main {
    padding: 20px;
}

article {
    background: #fff;
    margin-bottom: 20px;
    padding: 20px;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

footer {
    background: #333;
    color: #fff;
    text-align: center;
    padding: 1em 0;
    position: absolute;
    bottom: 0;
    width: 100%;
}

body.dark-mode {
    background-color: #333;
    color: #fff;
}

body.dark-mode header, body.dark-mode footer {
    background: #000;
}

body.dark-mode article {
    background: #444;
    color: #fff;
}