Nav menu appears under grid items

My nav menu is appearing below grid items even though I have a very high Z-Index set for my menu. How do I fix this behavior? Here’s my read-only link.

Maybe change position from sticky to absolute

Why does the section below jump up when I change from absolute to sticky?

Because Absolute pushes the other elements down, sticky doesn’t.
I believe there is a video detailing all the different lay outs. I believe it’s the position video under layout&design