code: function normalize(values) {
    if (values[0].toLowerCase() === auto) {
      return values[1];
    }
  
    if (values[1].toLowerCase() === auto) {
      return values[0];
    }
  
    if (
      values[0].toLowerCase() === inherit &&
      values[1].toLowerCase() === inherit
    ) {
      return inherit;
    }
  
    return values.join(' ');
  }
docs: Normalize a columns shorthand definition. Both of the longhand
  properties' initial values are 'auto', and as per the spec,
  omitted values are set to their initial values. Thus, we can
  remove any 'auto' definition when there are two values.
  
  Specification link: https://www.w3.org/TR/css3-multicol/