code: function establishContainer(node) {
    return node.parent.type === 'atrule' && node.parent.name !== 'critical' ? _postcss2.default.atRule({
      name: node.parent.name,
      type: node.parent.type,
      params: node.parent.params,
      nodes: [node]
    }) : node.clone();
  }
docs: Establish the container of a given node. Useful when preserving media queries
  or other atrules.
  
  @param {Object} node PostCSS node.
  @return {Object} A new root node with an atrule at its base.