diff --git a/ccp/css/common.css b/ccp/css/common.css
index aa08480..2d23678 100644
--- a/ccp/css/common.css
+++ b/ccp/css/common.css
@@ -15,4 +15,9 @@
   font-size: .6rem;
   font-weight: bold;
   vertical-align: super;
+}
+
+ccp-input-widget *:invalid::after{
+  color: red;
+  content: "!";
 }
\ No newline at end of file
diff --git a/ccp/executionformfragment.html b/ccp/executionformfragment.html
index 4bc7c5a..a6a4708 100644
--- a/ccp/executionformfragment.html
+++ b/ccp/executionformfragment.html
@@ -1,6 +1,9 @@
 <div>
   <link rel="stylesheet" href="https://nubis1.int.d4science.net:8080/ccp/css/common.css"></link>
   <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.0.0/dist/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
+  <style>
+    
+  </style>
   <template id="EXECUTION_FORM_TEMPLATE">
     <div name="execution_form">
       <h3></h3>