Checkbox and radio button will not show in firefox

Dear WPMUDEV hero,
I need some help. I use "formidable pro" for my forms. The form works great in chrome but the radio buttons and the checkbox are missing when opening the form in firefox. You can find the form here:
I used the text widget to insert the shortcode. After inspecting the the form in firebug, I saw that a global theme style might be causing the problem. I was trying to give the text widget a new Style and add custome css to set the position of the missing elements, but was unable to do so. Every time I went back to try some other css the previous code was gone. The custom style was still active but in the code editor was empty every time. Is that what happens, when the code entered is not css? :slight_smile: (that is very possible, when I consider my css skills). I was reading the wpmudev forum and saw, that you suggested someone with a similar problem to add some code to their css. If the solution with formidable pro is as simple as with other form plugins, please help me to find the right place to enter the css. I am still learning and my attempts to use the style function in the text widget containing the form shortcode failed. The form is already online. So I would really appreciate your help, before to many people complain about the form.

As always, I would not know what to do without you guys and girls!
Hope you are having a great day

Support access is granted!