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

nav li {
    position: relative;
}

nav a {
    display: block;
    padding: 10px 15px;
    text-decoration: none;
    color: #333;
}

nav ul ul {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: #fff;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

nav li:hover > ul {
    display: block;
}

@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
    }

    nav ul ul {
        position: static;
        box-shadow: none;
    }
}