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.
The Mobile Responsive Widget description says this.
The widget automatically detects the device where the form is opened, and applies a Custom Style sheet that will make the fields of the form to resize their widths according to the device screen size.
There is no additional configuration required by the widget - Just add it to your form and the widget will do the rest.
Hope this help. Let us know if you need further assistance.