html,
body {
  height: 100%;
}

body {
  margin: 0;
  padding: 0;
}

.container {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}
.box {
  width: 25%;
  height: 25%;
}

@media only screen and (max-width: 600px) {
  .box {
    width: 45%;
    height: 45%;
  }
}