How to create no background behind form, or make it transparent

Can I set the background to transparent instead of white?

Try to place this code into your custom CSS: 

.supernova {

  background-color: transparent !important;

}

Here is the link, how you can inject CSS code into your form:

https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

Let me know how it goes?