use directories for structure

node_modules/minify/lib/css.js

@@ -9,14 +9,17 @@ const Clean = require('clean-css');
  * minify css data.
  *
  * @param data
+ * @param userOptions - (optional) object that may contain a `css` key with an object of options
  */
-module.exports = (data) => {
+module.exports = (data, userOptions) => {
     assert(data);
     
+    const options = userOptions && userOptions.css || {};
+    
     const {
         styles,
         errors,
-    } = new Clean().minify(data);
+    } = new Clean(options).minify(data);
     
     const [error] = errors;