fix: mark package as having side effects

Fixes #529

Author: Matt Lewis

package.json

@@ -187,5 +187,8 @@
     "date-fns": "^1.28.5",
     "positioning": "^1.3.1"
   },
-  "sideEffects": true
+  "sideEffects": [
+    "*.css",
+    "*.scss"
+  ]
 }