@media screen and (max-width: 480px) {
    body {
        font-size: 100%;
        background-color: #00a665;
    }
    header nav {
        display: none;
    }
    header h3 {
        display: none;
    }
    header h1 {
        font-size: 2em;
        text-align: center;
    }
}