@media only screen and (max-width: 600px) {
    nav ul {
        flex-direction: column; /* Stack the menu items vertically on small screens */
    }

    nav ul li {
        width: 100%; /* Full width for each menu item */
    }

    /* Optionally adjust header h1 font size for smaller screens */
    header h1 {
        font-size: 20px; /* Smaller font size for mobile devices */
    }
}