I have div, '#bg' into which the viewer can import a chosen background, eg 'div#apples', 'div#oranges', etc.

div#bg is positioned and z-indexed above the body and below the content.

In some cases, 'div#apples' will actually be a stack of images--say six-- which are scripted to fade to reveal the next one underneath.

Logically, you'd position these multiple images z-index:6; :5, :4 etc.

But the question is, what happens when that stack is imported into div#bg ? Assuming it expands to accommodate the six layers, does there need to be six z-indexes between the body and the content?