diff --git a/stories/assets/main.scss b/stories/assets/main.scss
index 88cfc92..f58d0e8 100644
--- a/stories/assets/main.scss
+++ b/stories/assets/main.scss
@@ -5,6 +5,11 @@
   margin: 0;
 }
 
+* :after,
+:before {
+  box-sizing: border-box;
+}
+
 .my-alert {
   position: fixed;
   bottom: 10px;