I have no idea how this is not 28.3333% width.

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

/* Two Column Layout */

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

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

  #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;
    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 #F00;
    margin-bottom: 60px;
  }

  body {
    background: #000;
  }

}