proper loader for sass (scss)

lib/pipeline/webpack.config.js

@@ -79,8 +79,12 @@ const base = {
   module: {
     rules: [
       {
-        test: /\.css$/,
+        test: /\.scss$/,
-        use: [{loader: 'style-loader'}, {loader: 'css-loader'}]
+        use: [
+          'style-loader',
+          'css-loader',
+          'sass-loader'
+        ]
       },
       {
         test: /\.scss$/,