body {
  position: relative;
  height: 100vh;
  background-color: #000;
  margin: 0;
}
#clock {
  font-family: Hack, monospace;
  font-size: 20vw;
  text-align: center;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  margin: 0;
  width: 100%;
  color: #FFF;
}

@media screen and (min-width: 1000px) {
  #clock { font-size: 200px; }
}