Assuming the nav bar is a floating Group, you should be able to bring it forward with a right click, then ‘bring to front’ (or something similar on one of the edit menus).
Is the navbar a reusable element, or just its own element on that particular page? If you plan on using this navbar on other pages, I recommend putting it in an RE if it isn’t already.
If the navbar is an RE, then make sure the entire RE is set as a floating group with a width of 100%.
If the navbar is not an RE, then ensure the element type is set to a floating group.
Keep in mind that you’ll have to add a top margin to the bottom 2 panels to ensure the top part of each panel is not covered by the floating group!