The z-index CSS property specifies the stack level of the box in the current stacking context and whether the box establishes a local stacking context.
object.style.zIndex = "value";
<'z-index'> = auto | <integer> | inherit
auto
Automatically specified by the user agent.
<integer>
Specifies one or more decimal digits (0-9).
inherit
Specifies the same value as the parent.