Revert "Allow css to fail (#3)"

This reverts commit abf021a8

.github/workflows/frontend.yml

diff --git a/.github/workflows/frontend.yml b/.github/workflows/frontend.yml
index ffd2581..58a3b31 100644
--- a/.github/workflows/frontend.yml
+++ b/.github/workflows/frontend.yml
@@ -30,7 +30,6 @@
       - name: lint
         run: cd frontend && npm run lint
       - name: lint-css
-        continue-on-error: true
         run: cd frontend && npm run lint-css
     
   test: