Move menu to overlap content

Hello there,

Just wondering if I could use a bit of CSS to move the menu down just to cover the top of the main content, currently, I’m using the GenerateBlocks plugin container and if I use minus top margin the content overlaps the menu, I would like the menu to be displayed over the content instead similar to the linked website above.

Any help would be welcome.

Thanks in advance.

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