Z-index

The   property is used in CSS and certain HTML elements. It specifies the z-order of an element and its descendants. When elements overlap, z-order determines which one covers the other. An element with a larger z-index generally covers an element with a lower one.

For a positioned box, the  property specifies:


 * 1) The stack level of the box in the current stacking context.
 * 2) Whether the box establishes a local stacking context.

Values

 * - 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.
 * - 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 . This means that the z-indexes of descendants are not compared to the z-indexes of elements outside this element.