z index on position absolute

1#relative {
2	position: relative;
3	width: 40px;
4	height: 100px;
5	background: #000;
6	z-index: 1;
7	margin-top: 30px;
8}
9.absolute {
10	position: absolute;
11	top: 0; left: 0;
12	width: 200px;
13	height: 50px;
14	background: yellow;
15}