.centerBG{
   height:100%;
   width: 70%;
   background-color: rgb(128,128,128);
   background-position:absolute;
   top: 0;
   right: 0;
   bottom: 0;
   left: 0;
   margin:auto;
   z-index: -99;
}

body{
   background-color: #000000;
}