Why would Openlayers always render over other divs?

I'm having trouble getting an Openlayers div to allow other divs to appear above it.

Having tried the solution proposed here as well as the more classy-looking one here, I haven't had any luck yet. Openlayers always orders itself over other divs. I've also set the z-index for my other div (which 开发者_运维知识库I want on top) as high as it goes, still no effect.

Is there somewhere it could be getting overridden? Or some setting that needs an extra trick to get rid of?

EDIT: Never mind, I got an answer and the problem was that I forgot to position the element. Just remember to add "position: relative;" (for example) to any element needing a z-index. Leaving this question here for others' edification, but it has been answered elsewhere.