body {
    background-color:yellowgreen;
    color: whitesmoke;
}

a {
    color:chartreuse;
}

#container {
    width: 40%;
    margin: 0 auto;
}

img {
    max-width: 100%;
}

@media (max-width: 500px) {
    #container {
        width: 90%;
    }
}