Z-Index Relative or Absolute?

Question

I\'m trying to find an answer to the following question:

Is an element\'s z-index style its absolute stack order, or its stack order relative to its parent?

Answer 1

Here is the W3C specification for z-index.

I think the most important line, based on your question is the following:

The order in which the rendering tree is painted onto the canvas is described in terms of stacking contexts. Stacking contexts can contain further stacking contexts. A stacking context is atomic from the point of view of its parent stacking context; boxes in other stacking contexts may not come between any of its boxes.

This seems to indicate that nothing can be drawn in between the div with z-index: -100 and the div with z-index: 200.