In this video i will talk about Layers and Z-index in CSS


The z-index CSS property sets the z-order of a positioned element and its descendants or flex items. Overlapping elements with a larger z-index cover those with a smaller one.

The z-index property is specified as either the keyword auto or an integer.

Values
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auto: The box does not establish a new local stacking context. The stack level of the generated box in the current stacking context is the same as its parent's box.

integer: This integer is the stack level of the generated box in the current stacking context. The box also establishes a local stacking context in which its stack level is 0. This means that the z-indexes of descendants are not compared to the z-indexes of elements outside this element.
Formal definition