Stacking Context

Created on: Sat 17 Oct 20 Updated: Tue 10 Jan 23

When?

Z-index and the stacking context are created when:

Items set to a position to be set to fixed, sticky, absolute or relative first for the z-index to work OR if a transform or opacity of less than 1 is applied
Nesting if an element is contained within a containing element it cannot be outside of it’s containing elements position.
Using transform or opacity (with a value below 1) can change an elements stacking context, by moving it up towards the top.
Child elements of a flexbox or grid container where the z-index is other than auto.
An element that has its mix-blend-mode set to other than normal.