--- a/editor/libeditor/HTMLAnonymousNodeEditor.cpp
+++ b/editor/libeditor/HTMLAnonymousNodeEditor.cpp
@@ -231,16 +231,22 @@ HTMLEditor::CreateAnonymousElement(nsIAt
       parentContent->GetProperty(nsGkAtoms::manualNACProperty));
   if (!nac) {
     nac = new ManualNAC();
     parentContent->SetProperty(nsGkAtoms::manualNACProperty, nac,
                                nsINode::DeleteProperty<ManualNAC>);
   }
   nac->AppendElement(newContent);
 
+  // Must style the new element, otherwise the PostRecreateFramesFor call
+  // below will do nothing.
+  if (ServoStyleSet* styleSet = ps->StyleSet()->GetAsServo()) {
+    styleSet->StyleNewSubtree(newContent);
+  }
+
   ElementDeletionObserver* observer =
     new ElementDeletionObserver(newContent, parentContent);
   NS_ADDREF(observer); // NodeWillBeDestroyed releases.
   parentContent->AddMutationObserver(observer);
   newContent->AddMutationObserver(observer);
 
 #ifdef DEBUG
   // Editor anonymous content gets passed to PostRecreateFramesFor... which