html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  background: transparent;
  overflow: hidden;
  position: relative;
}

#timer {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 10vw;
  color: #ffffff;
  font-family: 'Consolas', monospace;
  text-align: center;
  white-space: nowrap;
}

#timer #time {
  position: relative;
  display: inline-block;
}

#timer #prefix {
  position: absolute;
  right: 100%;
  margin-right: 0.2em;
}

#operation {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, calc(-100% - 5vh));
  font-size: 4vw;
  color: #ffffff;
  font-family: 'Consolas', monospace;
  text-align: center;
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
}