diff --git a/assets/css/general.css b/assets/css/general.css
index 3e3f7cec..a2ad3e2a 100644
--- a/assets/css/general.css
+++ b/assets/css/general.css
@@ -550,4 +550,8 @@ div#station_logbooks_linked_table_paginate {
 }
 #simpleFleInfo h2 {
     margin-right: 30px; 
-}
\ No newline at end of file
+}
+
+input:invalid {
+    border-color: red;
+ }
\ No newline at end of file