header {
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
}

nav {
    background-color: #444;
    overflow: hidden;
}

nav a {
    float: left;
    display: block;
    color: #fff;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

nav a:hover {
    background-color: #666;
}

main {
    padding: 20px;
    background-color: #fff;
    max-width: 800px;
    margin: 0 auto;
}

footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 10px;
}

.box {
    border: 1px solid #ccc;
    padding: 20px;
    margin: 20px;
    background-color: #fff;
}


.box {
    border: 1px solid black;
    padding: 20px;
    margin: 10px;
    background-color: #f4f4f4;
}


        body {
            font-family: Arial, sans-serif;
            margin: 0;
            padding: 20px;
        }
        .container {
            max-width: 800px;
            margin: 0 auto;
            background-color: #f4f4f4;
            padding: 20px;
            border: 1px solid #ddd;
            border-radius: 5px;
        }
        .dark-theme {
            background-color: #333;
            color: #fff;
        }
        #slideShow img {
            display: none;
        }
        #slideShow img.active {
            display: block;
        }
        .highlight {
            border: 2px solid blue;
        }