body {
background-image: url('https://cdn.imgchest.com/files/3719529a7cde.gif');
background-attachment: fixed;
background-repeat: repeat;
height: 100%;

}

iframe {
  overflow: auto;
  height: 100%;
  width: 100%;
  display: block;
}

.gamediv{
  overflow: auto;
  height:100%;
  width: 100%;
  position: absolute;
top: 0px;
left: 0px;
}