html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

#app {
  width: 100%;
  height: 100%;
}

.bg,
.tree,
.stars,
.stars2 {
  width: 100%;
  height: 100%;
}

.bg {
  background: url(/img/space-bg.png) center center no-repeat;
  background-size: cover;
}
.tree {
  background: url(/img/tree.png) center center no-repeat;
}
.stars {
  background: url(/img/stars.png) center center no-repeat;
}
.stars2 {
  background: url(/img/stars2.png) center center no-repeat;
}