With this feature you're able to push the top row on each page up behind your header, creating a transparency effect that makes your header seamlessly blend in with the overall style of your site.
By enabling this feature, your background image or color in the top row of a page will become visible behind the header, if you have made your header transparent in Global Styling. You can only enable the feature on the top row or row group of a page.
Top row behind header
How to enable "Place Top Row Behind Header"
To enable this feature, edit the top row on a page, click the Settings tab, and toggle "Place Top Row Behind Header"
Note! The row will only be visible behind the header in the preview and published versions of the site. You will not be able to see the change while you are in Build mode.