How do I make the borders on my form stand out more?

How do I make the borders on my form stand out more? Color change to black or dark blue? How do I do that?

You need to override the existing custom style in the form to change the border color. Add the following custom CSS codes;

.supernova .form-all, .form-all {

    border: 1px solid #04406f !important;

}

Change #04406f to your desired color. 

Here's how to inject the codes: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes. Put it to the bottom of the existing codes. 

Color reference: https://www.w3schools.com/colors/colors_picker.asp