Responsive navigation object BEM, see: http://codepen.io/Anderson-Juhasc/pen/wmHcD

gistfile1.sass

.nav-responsive {
  list-style: none;
  padding-left: 0;
}

.nav-responsive__item {
  display: block;
  border-bottom: 1px solid #999;
  
  &:last-child {
    border-bottom: none;
  }
  
  @media only screen and (min-width: 700px) {
    display: inline-block;
    border-bottom: none;
    border-right: 1px solid #999;
    
    &:last-child {
      border-right: none;
    }
  }
}

.nav-responsive__link {
  display: block;
  padding: 8px;
}

gistfile2.html

<ul class="nav-responsive">
  <li class="nav-responsive__item"><a href="#" class="nav-responsive__link">Link</a></li>
  <li class="nav-responsive__item"><a href="#" class="nav-responsive__link">Link</a></li>
  <li class="nav-responsive__item"><a href="#" class="nav-responsive__link">Link</a></li>
  <li class="nav-responsive__item"><a href="#" class="nav-responsive__link">Link</a></li>
</ul>