CSS z-index property

Description of property definition and use

The z-index property specifies the stacking order of an element.

Elements with a higher stack order are always in front of elements with a lower stack order.

Note: z-index locates elements (position:absolute, position:relative, or position:fixed).

Value	Describe
auto	Default. The stacking order is equal to that of the parent element.
number	Set the stacking order of the elements.
inherit	Specifies that the value of the z-index property should be inherited from the parent element.

The numbers in the table support the first browser version number of the property.

Attributes
z-index	1.0	4.0	3.0	1.0	4.0

Set the z-index of the image:

Img
{
position:absolute;
left:0px;
top:0px;
z-index:-1;
}