html {
  height: 100%;
}
body {
  display: flex;
  margin: 0;
  flex-direction: column;
  justify-content: space-between;
  text-align: center;
  height: 100%;
  font-size: 3vw;
}
.start, .middle, .end {
  padding: 1vw;
}
.middle {
  font-size: 18vw;
}