.body {
  background-color: white;
  font-family: sans-serif;
}

.container {
  padding: 1em;
}

.title {
  text-align: center;
  text-transform: uppercase;
  font-size: 1em;
}

.buttons {
  text-align: center;
}

.button {
  width: 75px;
  height: 75px;
  border-radius: 37.5px;
  background-color: white;
  border: 1px solid #999;
  text-transform: uppercase;
  color: #999;
  font-size: 1em;
  text-align: center;
  margin: .25em;
}

.button:hover {
  cursor: pointer;
}

.button:focus {
  outline: none;
  background-color: #999;
  color: white;
  font-weight: bold;
}

.timer {
  text-align: center;
  margin: 10px;
  font-size: 60px;
}

.timer.started {
  opacity: 1;
}

.timer:not(.started) {
  opacity: .5;
}