my layout keeps breaking when larger than 480px.

@media screen and (min-width: 480px) {

    /*** contact page ***/

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

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

    /*** PORTFOLIO PAGE ***/

    #gallery li {
        width: 28.3333%;
        }
    /* this is to prevent text from wrapping and breaking the layout, but it's not working!!! */
    #gallery li:nth-child(4n) {  
        clear: left;              
        }

    /*** PROFILE PHOTO PAGE ***/
    /*** we can float the profile picture to the left when the page reaches 480px ***/
    .profile-photo {
        float: left;
        margin: 0 5% 80px 0;
        }
}

@media screen and (min-width: 660px) {
    nav { 
    background: none; /* text can sit against the header background now since its been removed */
    float: right;
    font-size: 1.125em;
    margin-right: 5%;
    text-align: right;
    width: 45%;
    }

    #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;
    }
}

/* all this code is probably broken or missing semi-colons or has no friends */

/**** GENERAL ****/
body  {
background-color: #fff;
color: #999;
font-family: 'Open Sans', sans-serif;
}

a { 
text-decoration: none;
color: #6ab47b;
}

#wrapper {
max-width: 940px;
margin: 0 auto;
padding: 0 5%;
}

img {
max-width: 100%;
}

h3 {
margin: 0 0 1em 0;
}



/****  ****/


/**** NAVIGATION ****/
nav {
background:  #599a68;
text-align: center;
padding: 10px 0;
margin: 20px 0 0;
}

nav a {
font-weight: 800;
padding: 15px 10px;
}

nav a, nav a:visited {
color: #fff;
}

nav a.selected, nav a:hover {
color: #32673F;
}

nav li {
list-style: none;
margin: 0 10px;
padding: 0;
display: inline-block;
}
/****  ****/



/**** HEADING ****/
header {
background: #6ab47b;
border-color: #599a68;
float: left;
margin: 0 0 30px 0;
padding: 5px 0 0 0;
width: 100%;
}


h1 {
margin: 15px 0;
font-family: 'Oswald', sans-serif;
font-size: 1.75em;
font-weight: normal;
line-height: 0.8em;
color: #fff;
}

h2 {
font-size: 0.75em;
margin: -5px 0 0;
font-weight: normal;
color: #fff;
}
/****  ****/



/**** 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;
}

#logo {
text-align: center;
margin: 0;
}

/****  ****/

/**** GALLERY *****/
#gallery {
margin: 0;
padding: 0;
list-style: none;
}

#gallery li {
float: left;
width: 45%;
margin: 2.5%;
background-color: #f5f5f5;
color: #bdc3c7;
}

#gallery li a p {
margin: 0;
padding: 5%;
font-size: 0.75em;
color: #0B6138;
}

/****  ****/

/**** PAGE: ABOUT ****/

.profile-photo {
display: block;
max-width: 150px;
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.mail a {
background-image: url('../img/mail.png');
}

.contact-info li.twitter a {
background-image: url('../img/twitter.png');
}
/****  ****/