html{
  height: 100%;
  margin: 0;
}

body {
  height: 100%;
  margin: 0;
  display: flex; /*使物件依序排列*/
  flex-direction: column; /*使物件垂直排列*/
  font-family: "Noto Sans TC", sans-serif;
}

.wrapper {
  flex-grow: 1;
}

h1 {
  font-family: "Concert One", cursive;
}

#number {
  font-size: 100px;
}

.btn span {
  font-size: 40px;
  color: #dc4e35;
}
.btn span:hover {
  color: red;
}

#first, #second, #third {
  display: none;
}