Comment by Jeema101

> z-index should be called z-order or depth and should Just Work on all elements (like it does on flex items).

Z-index is one of the most aggravating things I've run into with CSS. It should always Just Work as the author says and be absolute across the whole page and intuitive. But it isn't. And every time I run into a problem where it's not behaving in the way I expect, I have to once again Google 'z index not working' and refresh my memory on all the reasons why it might not be working with the specific example I'm dealing with.