What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
I'm not sure if I understand you correctly but you can embed the form using it's source code. That way your website's styling might override the form's styling. You can't do that using iFrame embed method because it's hosted in different domain but the source code method might work.
Do let us know if you need further assistance.