create class have same height with parent

.box {
  display: inline-block;
}
.box:nth-child(1) {
  background: red;
}
.box:nth-child(2) {
  background: green;
}
.box:nth-child(3) {
  background: blue;
}

.container {
  width: 100px;
  height: 100px;
}

.container-2 {
  width: 200px;
  height: 200px;
}