message: Fix postcss plugin
  Enable the `includes` option by default.
diff: @@ -15,8 +15,8 @@ const defaults = {
  export default function (userOptions = {}) {
  return (site) => {
  const options = merge({
  - includes: site.src("_includes"),
  ...defaults,
  + includes: site.src("_includes"),
  }, userOptions);
  const plugins = [...options.plugins];
  @@ -38,10 +38,7 @@ export default function (userOptions = {}) {
  const map = options.sourceMap ? { inline: false } : undefined;
  // Fix the code with postcss
  - const result = await runner.process(
  - page.content,
  - { from, to, map },
  - );
  + const result = await runner.process(page.content, { from, to, map });
  page.content = result.css;
  