.navbar-center{
  display: block;
  width: 100%;
  float: none;
  text-align: center;

  > li{
    display: inline-block;
    float: none;
  }
}

.navbar-center{
  display: block;
  float: none;
  text-align: center;

  @media (min-width: $screen-sm-min) {
    > li{
      display: inline-block;
      float: none;
    }
  }
}

Add navigation bar RWD layout
Add navigation bar RWD layout
