* {
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
  margin: 0;
  padding: 0;
}

html,
body {
  width: 100%;
  height: 100%;
}

html {
  font-size: 62.5%;
}

@media (min-width: 112.5em) {
  html {
    font-size: 75%;
  }
}

@media (max-width: 75em) {
  html {
    font-size: 56.25%;
  }
}

@media (max-width: 56.25em) {
  html {
    font-size: 50%;
  }
}

#button {
  margin: 2rem;
  font-size: 5rem;
  width: 15rem;
}

@media (max-width: 56.25em) {
  #button {
    font-size: 3rem;
  }
}

#menu {
  position: absolute;
  height: 15rem;
  width: 10rem;
  background-color: blue;
  opacity: 0.3;
}

#image {
  height: 10rem;
}

.back {
  font-size: 4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transform: rotateY(180deg);
  background-color: lightblue;
  border: 0.2rem solid white;
  border-radius: 5px;
}

.card {
  height: 10rem;
  width: 7.2rem;
  margin: 1rem;
  cursor: pointer;
  perspective: 150rem;
  -moz-perspective: 150rem;
}

.card:active {
  transform: scale(0.95);
}

.card--side {
  position: absolute;
  height: 10rem;
  width: 7.2rem;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transition: all 0.8s ease;
}

.card:hover .front {
  transform: rotateY(-180deg);
}
.card:hover .back {
  transform: rotateY(0deg);
}

#container {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

#input-box {
  width: 100%;
  /* height: 10rem; */
  padding: 2rem;
}

#form {
  display: flex;
  justify-content: space-around;
  align-items: center;
}

@media (max-width: 56.25em) {
  #form {
    flex-direction: column;
  }

  #input-box {
    /* height: 15rem; */
  }
}

#input-label {
  font-size: 2rem;
}

#input {
  text-align: center;
  background-color: none;
  border: none;
  border-bottom: 0.1rem solid red;
  color: red;
  font-size: 4rem;
  width: 40rem;
}