nav { 
    background-color: white;
    box-sizing: border-box;
} 

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

nav li { 
    border-top: 1px solid blue;
    padding: .5em;
}

nav li:hover {
    text-decoration: underline;
}

nav li a {
    text-decoration: none;
    color: blue;
}

header h1 {
    color: white;
    font-family: Georgia, serif;
    font-size: 2.5em;
    font-variant: small-caps;
    text-align: center;
}

header { 
    background-color: navy;
    box-sizing: border-box;
    padding: 2em 1em;
} 

footer { 
    background-color: navy;
    box-sizing: border-box;
    clear: both;
    color: white;
    font-size: .8em;
    padding: 2em;
    text-align: center;
}

@media screen and (max-width: 48em) {
    /* For smartphones */
    nav ul, article {
        max-width: 200px;
        margin: 0 auto;
    }
    nav {
        font-size: 15px;
    }
    nav ul {
        display: -webkit-box;
        display: -ms-flexbox;
        display: block;
     }
    nav ul li {
        border-top: none;
        -webkit-box-flex: 1;
        -ms-flex-positive: 1;
        flex-grow: 1;
    }
    nav li {
        text-align: center;
    }
}


@media screen and (min-width: 48em) {
    /* For tablets and desktops */
    nav ul, article {
        max-width: 1000px;
        margin: 0 auto;
    }
    nav {
        font-size: 20px;
    }
    nav ul {
        display: -webkit-box;
        display: -ms-flexbox;
        display: flex;
     }
    nav ul li {
        border-top: none;
        -webkit-box-flex: 1;
        -ms-flex-positive: 1;
        flex-grow: 1;
    }
    nav li {
        text-align: center;
    }
}