background.css

.box {
  width: 300px;
  height: 300px;
  margin: 0 20px 20px 0;
  border: 1px solid;
  display: inline-block;
}

.orange-tree {
  background: url('http://i.imgur.com/bwy74ok.jpg');
  background-size: cover;
}

.thunder-cloud {
  background: url('../../../test/img/thunder-cloud.jpg');
  background-size: contain;
}

.multi1 {
  background:
    url("http://i.imgur.com/ZAVN3.png"),
    url('http://i.imgur.com/6UdOxeB.png') bottom right,
    url(http://i.imgur.com/LkmcILl.jpg);
  background-size: cover;
}

.blue {
  background: #09F;
}