body {
    text-align: left;
    background-color: #f5f5f5; 
    color: #333;
    font-family: Arial, Helvetica, sans-serif;
    margin: 10px;
}

header {
    text-align: center;
}

nav {
    text-align: center;
}

footer {
    text-align: center;
}

nav a {
    margin: 0 10px;
}

figure {
    display: inline-block;
}

img {
    display: block;
    margin: 0 auto;
}

iframe {
    display: block;
    margin: 20px auto;
}

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