Help with CSS styling

The spacing problems are coming from your theme styles. If you look on line 925 of your style.css file, you'll see that it is setting the top and bottom margins to 0. If you disable that rule, you'll notice the form spacing in general is improved (not just the section breaks)

screenshot: http://grab.by/9Ovi

To target just an individual field, in this case the "contact information" section container, you would view your page source, find the ID on that field container and target it for manipulation. In your form, the list container id is "field_3_17".

You would add this to the end of your theme stylesheet.

[css]
body .gform_wrapper .gform_body .gform_fields #field_3_17.gsection {margin:30px 0;}

This was taken directly from the CSS targeting samples documentation you referenced.. look for "section break container".

http://www.gravityhelp.com/documentation/page/CSS_Targeting_Samples

You can refer back to that for more examples of how to apply styles to specific fields or globally should you need.

Yes, you could comment the margin portion out, but it may affect the list spacing in your other content.

Try adding this to the end of your style.css file. It should override the margin settings it's inheriting and reset them to the default form styles.

[css]
#content .post .gform_wrapper ul li,
#content .page .gform_wrapper ul li,
.catalyst-widget-area .gform_wrapper ul li  {
	margin: 0 0 14px 0
}

There is another similar rule in this stylesheet.. dynamik-min.css on line 2.

Have you tried adding the last snippet I gave you to your stylesheet? I believe that should fix it for you.