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.
We do, however, offer a way to apply your own Custom CSS to many such widgets. By using custom CSS on these widgets, you are able to achieve the same or similar look to that of your form.
I have cloned one of your forms to check, and it seems that you are using the Field Multiplier widget, which unfortunately does not support custom CSS. If you wish to be able to achieve the same look on a widgets input fields as the rest of your theme, it may be better to use the Infinite List widget.
Here is a cloned version of your form, with Infinite List widget added under the Field Multiplier, so that you can see how the Infinite List would fit with the rest of your theme:
I hope this helps. Please let us know if you need further assistance, we will be happy to help.