var rimage = new Array();

rimage[0] = "imgs/bannerelement.gif";
rimage[1] = "imgs/bannerelement1.gif";
rimage[2] = "imgs/bannerelement2.gif";
rimage[3] = "imgs/bannerelement3.gif";
rimage[4] = "imgs/bannerelement4.gif";
rimage[5] = "imgs/bannerelement5.gif";
rimage[6] = "imgs/bannerelement6.gif";
rimage[7] = "imgs/bannerelement7.gif";
rimage[8] = "imgs/bannerelement8.gif";
rimage[9] = "imgs/bannerelement9.gif";
rimage[10] = "imgs/bannerelement10.gif";
rimage[11] = "imgs/bannerelement11.gif";
rimage[12] = "imgs/bannerelement12.gif";
rimage[13] = "imgs/bannerelement13.gif";
rimage[14] = "imgs/bannerelement14.gif";
rimage[15] = "imgs/bannerelement15.gif";

var index = Math.floor(Math.random() * rimage.length);

document.write("<div id='headerOverlap'");
document.write(" style='background-image: url(" + rimage[index] + ")'></div>");