body {
    font-family: sans-serif;
    margin: 0;
    padding: 0;
    background: #fff;
    color: #333;
}
header {
    background: #f0f0f0;
    padding: 1rem;
}
nav ul {
    list-style-type: none;
    padding: 0;
}
nav ul li {
    position: relative;
    display: inline-block;
    margin-right: 1rem;
}
nav ul li ul.dropdown {
    display: none;
    position: absolute;
    left: 0;
    background: #f9f9f9;
    padding: 0.5rem;
}
nav ul li:hover ul.dropdown {
    display: block;
}
nav a {
    text-decoration: none;
    color: #333;
}