* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
}

header {
    background-color: #333;
    color: #fff;
    padding: 1rem;
}

nav ul {
    list-style-type: none;
}

nav ul li {
    display: inline;
    margin-right: 1rem;
}

nav ul li a {
    color: #fff;
    text-decoration: none;
}

main {
    padding: 2rem;
}

section {
    margin-bottom: 2rem;
}

footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 1rem;
}

@media screen and (max-width: 768px) {
    header {
        text-align: center;
    }
    
    nav ul li {
        display: block;
        margin-bottom: 0.5rem;
    }
}