Is it possible to change the z-index of page elements without coding?

I am trying to create a nav bar that is on the bottom of the page, when you scroll it stickies to the top, along with the links.

As you scroll further, different page elements overlap the background of the nav element, with the text staying on top.

I have tweaked the position settings to the very top, but same old same old

Any help would be greatly appreciated!