How do you make sure your annoying popup is shown on top of every other element in the page, when you don’t know how many there are, who wrote them, and how bad they wanted their elements to be on top? That’s when you set your z-index to 100, or maybe 999, or maybe, just maybe 99999 to be really sure yours will win.
That, at least, is how I write my CSS. In the rest of this post, we will look at millions of z indices to see what everyone else does.
Of course, if you make websites for a living you’ll find this interesting. Like most things available here.