filterAtrule = function (node, accepted) {
  if (node.is('atrule')) {
    if (node.contains('atkeyword') && node.first('atkeyword').contains('ident')) {
      if (accepted.indexOf(node.first('atkeyword').first('ident').content) === -1) {
        return true;
      }
    }
  }
  return false;
}
Filter at-rules

@param {Object} node - The node to filter
@param {Array} accepted - The array of accepted at-rule types
@returns {bool} true if we should ignore, false to continue