Remove all CSS comments from minified files

gulpfile.js

@@ -31,6 +31,17 @@ elixir.config.js.folder = '';
  */
 elixir.config.css.folder = '';
 
+/**
+ * Remove all CSS comments
+ *
+ * @type {{discardComments: {removeAll: boolean}}}
+ */
+elixir.config.css.cssnano.pluginOptions = {
+    discardComments: {
+        removeAll: true
+    }
+};
+
 /**
  * Directory for bower source files.
  * If changing this, please also see .bowerrc