html,
body {
  height: 100%;
}
#container {
  display: flex;
  flex-wrap: wrap;
  width: 300px;
  height: 300px;
  margin-top: 20px;
  border: 3px solid #3b5998;
  text-align: center;
  vertical-align: middle;
  font-size: 7rem;
}

#container > .card {
  box-sizing: border-box;
  width: 100px;
  height: 100px;
  border: 1px solid #3b5998;
  font-size: 5rem;
  text-align: center;
}

input {
  align-self: center;
  font-size: 2rem;
  margin-top: 50px;
}

.time {
  font-size: 3rem;
  text-align: center;
}

#box {
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
}