div {
position:absolute; width:250px; height:100px; border:5px solid #000; color:black; font-weight:bold; text-align:center;
}
div#d1 { background-color:red; left:0px;
top:0px;
z-index:0;
}
div#d2 { background-color:green; left:75px;
top:25px;
z-index:3;
}
div#d3 { background-color:blue; left:150px;
top:50px;
z-index: 2;
}
div#d4 { background-color:yellow; left:225px;
top:75px;
z-index: 1;
}