body {
  text-align:center;
  background-color:gray;
}
#content {
  background: url(../grafik/strube_ground_wh.jpg) no-repeat;
  height: 560px;
  width: 760px;
  position:absolute;
  top: 50%;
  left: 50%;
  margin: -280px 0 0 -380px;
}
IMG.relative {
  position:relative;
  top:0px;
  left:0px;
}
object.relative {
  position: relative;
  top: 150px;
  left:44px;
}