Is custom code interfering with page spacing?

Site URL: https://www.chrisclearfield.com/conference

I'm editing a website that I didn't build, and am having an issue where there is an annoying space between the header navigation menu and the body content.  The theme is Brine.

In site styles, the only option to adjust the padding is the make the header comically large to cover the space, but I can't figure out why I can't move the body content block up to the header otherwise. 

It looks like whomever set up the site used some custom code and I'm wondering if that's somehow interfering with the spacing issue.  It's across all pages of the site.  I'm not a seasoned coder and I'm working with a limited knowledge of it, so I'm hesitant to try to make changes without a little guidance first.

I've uploaded screenshots of the page with the space visible and with the header enlarged to mask it.  I'm working on a specific unlinked page, but the issue persists across the entire website.

Can anyone offer some potential solutions to try and reduce the space since there is no option in site styles that currently affects it at all?

Thanks

Can you take screenshot that spacing?

You mean red 1 or red 2?

It's Red 1 - the gray line you see there is the space that enlarged when the header (Red 1) is adjusted.

Add to Home > Design  > Custom CSS

.Header-inner.Header-inner--top {
    padding-bottom: 10px;
}