* {
  margin:0;
  padding:0;
  border:0;
}
html, body { 
  height:100%;
  min-height:100%;
  background: url('bg.png');
  background-repeat: no-repeat;
  background-size:100% 100%;
}
div.logo {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 400px;
  height: 150px;
  margin-top: -75px;
  margin-left: -200px;
}