save.css

/* Common styles for both mobile and desktop */
body {
    font-family: Arial, sans-serif;
    background-image: url("Avengers.gif");
    margin: 0;
    padding: 0;
    color: aliceblue;
}

.container {
    text-align: center;
    padding: 20px;
    background-color: red;
    margin: 20px;
}

.navbar {
    background-color: black;
    padding: 10px 0;
    text-align: center;
}

.navbar ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.navbar ul li {
    display: inline;
    margin-right: 20px;
}

.navbar ul li a {
    text-decoration: none;
    color: white;
    font-weight: bold;
}

/* Mobile responsiveness */
@media (max-width: 768px) {
    .navbar ul li {
        display: block;
        margin: 10px 0;
    }
}

/* Desktop responsiveness */
@media (min-width: 769px) {
    .container {
        max-width: 960px;
        margin: 0 auto;
    }
}