Help with header/navbar visibility

Hi – searched in the forum and couldn’t find the answer to this one.

when I look at one of the demo pages for the theme (https://demo.themeisle.com/clarina/) I see the full background image through the navbar that turns to white as I scroll down. The only two options I’ve found are either: leave the navbar white all the time (as it shows now on our new site) or tick the “header visibility” check box that completely hides the navbar until scrolling.

How do I get my header/navbar to function as on the demo site?

The page I need help with: [log in to see the link]