Problem at the nav

body{
font-family: 'Open Sans',sans-serif;
}

#wrapper {
    max-width: 948px;
    margin: 0 auto;
    padding: 0 5%;
}

a {
    text-decoration: none;
}

img{
    max-width: 100%;
}

h3{
   margin:0 0 1em 0;
}

/******************************
HEADING
******************************/
header{
    margin:0 0 30px 0;
    padding: 5px 0 0 0;
    width:100%;
    float:left;
}

#logo {
    text-align: center;
    margin:0;
}
h2{
    font-size: 0.75em;
    margin: -5px 0 0;
    font-weight: normal;
}
h1 {
    font-family: 'Changa One', sans-serif;
    margin:15px 0px;
    font-size: 1.75em;
    font-weight: normal;
    line-height: 0.8em;
}

/******************************
NAVIGATION
******************************/

nav {
text-align: center;
padding: 10px;
margin:20px 0 0;
}
nav ul {
    list-style: none;
    margin:0 10px;
    padding: 0;

}
nav li {
    display: inline-block;
}
nav a {
    font-weight:800;
    padding:15px 10px;

}


/******************************
FOOTER
******************************/

footer {
    font-size: 0.75em;
    text-align: center;
    padding-top: 50px;
    color:#ccc;
    clear: both;
} 
.social-icon{
    width:20px;
    height:20px;
    margin:0 5px;
}

/******************************
Page Portofolio
******************************/
#gallery {
    margin:0;
    padding: 0;

}

#gallery li{
    float: left;
    width:45%;
    margin:2.5%;
    background-color: #f5f5f5;
    color:#bdc37c;
    list-style: none;
}

#gallery li a p {
    margin:0;
    padding: 5%;
    font-size: 0.80em;
    color:#bdc37c;
}

/******************************
PAGE ABOUT
******************************/
.profile-photo {
    display: block;
    max-width: 175px;
    margin: 0 auto 30px;
    border-radius: 100%;
}

/******************************
Page Contact
******************************/
.contact-info{
    list-style: none;
    padding: 0;
    margin:0;
    font-size:0.9em;
}
.contact-info a{
display: block;
min-height: 20px;
background-repeat: no-repeat;
background-size: 20px 20px;
padding:0 0 0 30px;
margin: 0 0 10px;
}
.contact-info li.phone a {
    background-image: url('../img/phone.png');
}
.contact-info li.e-mail a {
    background-image: url('../img/mail.png');
}
.contact-info li.instagram a {
    background-image: url('../img/twitter.png');
}

/******************************
COLORS
******************************/

/* site body*/
body{
    background-color: white;
    color: #999;
}

/* green header*/
header {
    background:#6ab47b;
    border-color: #599a68
}

/* logo text*/
h1,h2{
    color:#fff;
}

/* links*/
a {
    color:#6ab47b;
}

/* nav background on mobile devices*/
nav {
background: #599a68;
}

/* nav link*/
nav a, nav a:visited{
    color: #fff;
}

/* selected nav link*/
nav a.selected, nav a:hover{
    color: #32673f;
}

@media screen and (min-width:480px) {
/******************************
TWO COLUMN LAYOUT
******************************/

#primary{
width:50%;
float: left;
 }

#secondary{
width: 40%;
float: right;
 }

}

/******************************
PORTOFOLIO
******************************/
#gallery li {
width:28.3333%;

}
#gallery li:nth-child(4n) {
    clear: left;
}

/******************************
PAGE ABOUT
******************************/
.profile-photo{
    float: left;
    margin: 0 5% 80px 0;
}

@media screen and (min-width:660px) {

/******************************
HEADER
******************************/
nav {
   background: none; 
   float: right;
   font-size: 1.125em;
   margin-right: 5%;
   text-align:right;

}

#logo{
   float:left;
   margin-left:5%;
   text-align: left;
   width:45%;

}
h1{
    font-size: 2.5em;

}
h2{
    font-size: 0.825em;
    margin-bottom: 20px;
}
header{
    border-bottom: 5px solid #599a68;
    margin-bottom: 60px;
}

}