* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

#time {
  color: white;
  font-size: 22px;
  margin-top: 150px;
}

#header2 {
  font-size: 22px;
  color: white;
  border: 2px solid whitesmoke;
  height: 40px;
  padding: 5px;
  border-radius: 5px;
  margin: 5px 5px;
  margin-left: 100px;
  width: 250px;
}

#header {
  font-size: 22px;
  color: white;
  margin-left: 100px;
  margin-top: 50px;
  border: 2px solid whitesmoke;
  height: 40px;
  width: 250px;
  padding: 5px;
  border-radius: 5px;
}

body {
  background: url("https://images.unsplash.com/photo-1451187580459-43490279c0fa?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=800&q=60;");
  height: 100vh;
  display: flex;
  background-size: cover;
  background-repeat: no-repeat;
  background-position: center;
}

.memorygame {
  width: 640px;
  height: 640px;
  display: flex;
  flex-wrap: wrap;
  margin: auto;
  perspective: 1000px;
}
.memorycard {
  width: 25%;
  height: 33.33%;
  position: relative;
  transform: scale(1);
  transform-style: preserve-3d;
  transition: 0.5s;
}

.memorycard:active {
  transform: scale(0.97);
  transition: 0.2s;
}

.front-face,
.back-face {
  position: absolute;
  width: 150px;
  height: 200px;
  border-radius: 10px;
  background: #1c7ccc;
  backface-visibility: hidden;
}

.memorycard.flip {
  transform: rotateY(180deg);
}
.front-face {
  transform: rotateY(180deg);
}

@media screen and (max-width: 768px) {
  .body {
    width: 100%;
    height: 100%;
  }

  #header2 {
    display: none;
  }

  #score {
    display: none;
  }
  .memorygame {
    width: 320px;
    height: 320px;
    display: flex;
    flex-wrap: wrap;
    margin: auto;
    perspective: 1000px;
  }
  .front-face,
  .back-face {
    position: absolute;
    width: 75px;
    height: 100px;
    border-radius: 10px;
    background: #1c7ccc;
    backface-visibility: hidden;
  }
  #header {
    display: none;
  }
}