Extending a placeholder with a clearfix

The factory class includes all the rules from the group placeholder by extending it. This is a recommended way to clearfix with full browser support.

%group {
  zoom: 1;
  &:before,
  &:after {
    content: '';
    display: table;
  }
  &:after {
    clear: both;
  }
}

.factory {
  @extend %group;
  background: #fff;
}