diff --git a/build/extract-css.js b/build/extract-css.js
index <HASH>..<HASH> 100644
--- a/build/extract-css.js
+++ b/build/extract-css.js
@@ -11,7 +11,7 @@ files.forEach((file) => {
   sass.render({
     file: `./src/css/${file}.scss`,
     outputStyle: 'compressed',
-    importer: tildeImporter,
+    importer: tildeImporter(),
   }, function(err, result) {
     if (err) {
       console.log(chalk.red('error!', err));
fix(css): fix utilities and reset build

this file previously used `node-sass-tilde-importer`, which was
passed in like `importer: tildeImporter`.
during the winter release, that package was replaced with
`node-sass-package-importer` which must be invoked like
this `importer: tildeImporter()`