style.css

nav,header,footer{
    display: block;
}
h1 {
    color: black;
}
body{
    background-image: url(pictures/fog-foggy-forest-4827.jpg);
    background-repeat: no-repeat;
    background-size: cover;
    line-height: 1;
    margin: 0;
}
nav{
    width: 100%;
    margin: 0;
}
nav ul {
    background-color:  #eee;
    overflow: hidden;
    margin: 0;
    padding: 0;
}

ul.topnva li{
    list-style: none;
    float: left;
}
ul.topnva li.topnav-right{
    list-style: none;
    float: right;
}
ul.topnva li a{
    display: block;
    text-decoration: none;
    min-height: 16px;
    padding: 14px;
    text-transform: uppercase;
    color: #666; 
}
ul.topnva li a:hover{
    background-color: blue;
    color: #fff;
}
ul.topnva li.dropdownIcon{
    display: none;
}


/*##################Mobile ############*/
@media screen and (max-width: 680px) {
    ul.topnva li:not(:nth-child(1)){
        display: none;
    }
    
    ul.topnva li.dropdownIcon{
        display: block;
    }
    
}