What may happen if an ad has a lower z-index than navigation elements?

When an ad has a lower z-index than navigation elements, it means that the navigation elements will be visually prioritized over the ad in terms of stacking order. The z-index is a CSS property that determines the order in which elements are layered on a webpage. Elements with a higher z-index will appear above those with a lower z-index. Therefore, if the navigation elements have a higher z-index, they will be rendered on top of the ad, which may result in those navigation elements obscuring the ad partially or entirely. The ad will still be present in the code and may still function, but it may not be fully visible to users due to being overlapped by these higher-z-index elements. This layering effect is crucial to ensure that essential navigational elements remain accessible and usable for the website visitors.