How to edit the error/warning page?

I need to know how to edit that section, looks terrible. 
Necesito saber cómo editar esa sección, se ve muy mal.

Hello,

As far as I understand, you'd like to modify the error page for your form. If yes, unfortunately, it is not possible at the moment. But, if you want, we could escalate a feature request on your behalf to get such option in future. 

We will wait for your reply.

If there is anything else we could assist you now, just let us know.

Thank you.