#nav {
  padding: 0; }
#nav ul {
  padding: 0;
  margin: 0;
  list-style: none; }
#nav ul li {
  border: 1px solid #4caf50;
  float: left; /* display inline in large screen */
  padding: 0;
  margin: 0 8px 0 0; }
#nav ul li a {
  display: block;
  padding: 8px 20px; }

@media (max-width:768px) {
  #nav ul li {
    float: none;  }
}