body { background:#000000 }


#outer {
  position: absolute;
  top: 50%;
  left: 0px;
  width: 100%;
  height: 1px;
  overflow: visible;
}
 
#inner {
  width: 800px;
  height: 520px;
  margin-left: -400px;  /***  width / 2   ***/
  position: absolute;
  top: -260px;          /***  height / 2   ***/
  left: 50%;
}