diff --git a/zebra/static/zebra/card-form.css b/zebra/static/zebra/card-form.css
index d77015b..7c686f7 100644
--- a/zebra/static/zebra/card-form.css
+++ b/zebra/static/zebra/card-form.css
@@ -1,9 +1,12 @@
 #id_card_number {
     width: 15ex;
+    box-sizing: content-box;
 }
 #id_card_cvv {
     width: 3ex;
+    box-sizing: content-box;
 }
 #id_card_expiry_year {
     width: 10ex;
-}
\ No newline at end of file
+    box-sizing: content-box;
+}