How do I customize the cognito hosted UI idp corporate email input

The corporate email input does not have a customizable class. The id of the input is socialSignUpCorporateEmail. I have tried using the id, as well as the classes attached to the input form-control and genericInputField however I hit validation errors when trying to use these classes since they are not in the allowed classes list.

Is there any reason this input is not customizable, would it be possible to allow customizability of this input field?