You can design a form with all the elements that you will be using and have them looking just right using the form builder.
When you have created a form design and put it to a HTML page, you can then save the css that's used and put that to a form.css file in your css folder.
Linking to that form.css from your main template, you can then create forms in DataAssist without any styling applied and then apply the template and the forms will take the style created from the form.css.
If you don't see the styling then look at the form input types and make sure they mach the input type in the css. will be something like
Hope this helps.