.box2{
  position: absolute;
  bottom: 0;
  right: 0;
}
.container{
  border: 2px solid black;
  width: 600px;
  margin: 50px;
}
.container div{
  width: 100px;
  height: 100px;
  border: 1px solid black;
}
.box1{
  background-color: mediumseagreen;
}
.container .box2{
  background-color: lightcoral;
  height: 120px;
}
.container .box3{
  background-color: cornflowerblue;
  height: 140px;
}