diff --git a/Examples/DynamicEditor/DynEditorExample.icl b/Examples/DynamicEditor/DynEditorExample.icl
index 494ec78a0444ab5d8ee29fa70f8cb99a58545153..fe8755afe2f364cfb7fe407a9e6e9b765bd4498f 100644
--- a/Examples/DynamicEditor/DynEditorExample.icl
+++ b/Examples/DynamicEditor/DynEditorExample.icl
@@ -264,7 +264,7 @@ taskEditor = DynamicEditor
           <<@@@ applyHorizontalClasses
       , functionConsDyn "Not" "not"
           (dynamic Typed Not :: Typed Func (Bool -> Bool))
-          <<@@@ applyHorizontalClasses
+          <<@@@ applyHorizontalClassesNoBorder
       ]
   , DynamicConsGroup "Comparison"
       [ functionConsDyn "Gt" "greater than"
diff --git a/Libraries/iTasks/Extensions/Editors/DynamicEditor.css b/Libraries/iTasks/Extensions/Editors/DynamicEditor.css
index 5daa9a69665d68f9a1d972aa53e10aeb64ac06cc..6beeb5f3a984e3e5046c8aa222ec9ad550ff93af 100644
--- a/Libraries/iTasks/Extensions/Editors/DynamicEditor.css
+++ b/Libraries/iTasks/Extensions/Editors/DynamicEditor.css
@@ -2,3 +2,6 @@
 	align-self: center;
 	padding: 0.2em;
 }
+.itasks-dynamic-editor-error {
+	background-color: #FFDDDD;
+}
diff --git a/Libraries/iTasks/Extensions/Editors/DynamicEditor.icl b/Libraries/iTasks/Extensions/Editors/DynamicEditor.icl
index e756b6b7d3c75d19f9c2b429efadef0a4b5d091c..bed22828c692f9595fd29b7bf62d811fdfe2c2b0 100644
--- a/Libraries/iTasks/Extensions/Editors/DynamicEditor.icl
+++ b/Libraries/iTasks/Extensions/Editors/DynamicEditor.icl
@@ -329,13 +329,16 @@ where
                 = editor.Editor.onEdit (dp ++ [0]) (tp, e) (childSts !! 1) vst
         = case res of
             Ok (change, childSt)
-				# change = ChangeUI [] $ [(0, ChangeChild $ ChangeUI [] [(argIdx + if hideCons 0 1, ChangeChild change)])] ++ mbErrorIconChange
+				# change = ChangeUI mbErrorIconAttrChange $ [(0, ChangeChild $ ChangeUI [] [(argIdx + if hideCons 0 1, ChangeChild change)])] ++ mbErrorIconChange
 				// replace state for this child
 				= (Ok (change, Just (cid, type, isOk typeIsCorrect), childSts`), vst)
 			where
-				mbErrorIconChange
+				(mbErrorIconChange, mbErrorIconAttrChange) = mbErrorIconUpd
+				mbErrorIconUpd
 					| typeWasCorrect && isError typeIsCorrect =
-						[(1, InsertChild errorIcon)]
+						( [(1, InsertChild errorIcon)]
+						, [SetAttribute "class" $ JSONArray [JSONString "itasks-container", JSONString "itasks-horizontal", JSONString "itasks-dynamic-editor-error"]]
+						)
 					with
 						errorIcon =
 							UI
@@ -347,8 +350,8 @@ where
 									[]
 								]
 					| not typeWasCorrect && isOk typeIsCorrect =
-						[(1, RemoveChild)]
-					| otherwise = []
+						([(1, RemoveChild)], [SetAttribute "class" $ JSONArray [JSONString "itasks-container", JSONString "itasks-horizontal"]])
+					| otherwise = ([], [])
 				typeIsCorrect = childTypesAreMatching cons.builder (drop 1 childSts`)
 				childSts` = updateAt (argIdx + 1) childSt childSts
             Error e = (Error e, vst)