Why is embedded spacing different than editor spacing?

Plz see title of this thread. I'm using the following injected CSS in the form editor:

.form-header-group
{
margin-bottom: 10px;
padding-bottom:10px;
}

here's how it looks in the editor. Note the horizontal line under the Heading:

here's how it looks on the webpage (Feedback style). What's the problem?

-thx

The edit view will be different from the view of the form itself. Are you looking for to show more vertical space between fields? If that is the case, maybe you can, you can adjust this from the Form Preferences

Please check this guide for more details

How to Reduce Vertical Spacing between Fields

Please see the pictures  I'm specifically talking about the space above and below the horizontal line  NOT talking about universal Question Spacing. Thx

It's a bottom border of the header. The only difference I've noticed is the spacing between the border and the full name. Are you specifically after of that? 

Can you send us the webpage link where the lightbox code is embedded? We'd like to check further.

Thank you!