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

body {
  height: 100vh;
  display: flex;
}

.memory-game {
  width: 640px;
  height: 640px;
  margin: auto;
  display: flex;
  flex-wrap: wrap;
  perspective: 1000px;
}

.memory-card {
  width: calc(25% - 10px);
    height: calc(33.333% - 10px);
    margin: 5px;
    position: relative;
    transform: scale(1);
    transform-style: preserve-3d;
    transition: transform .5s;
    box-shadow: 1px 1px 1px rgba(0, 0, 0, .3);
    background: #1C7CCC;
    border-radius: 5px;
    border: 10px solid #06579b;
    margin: 5px;
    display: flex;
    align-items: center;
}

.memory-card:active {
  transform: scale(0.97);
  transition: transform .2s;
}

.memory-card.flip {
  transform: rotateY(180deg);
}

.front-face, .back-face {
width: 100%;
    position: absolute;
    border-radius: 5px;
    backface-visibility: hidden;
}

.front-face {
  transform: rotateY(180deg); filter: drop-shadow(3px 3px 0px #13558d);
}

img.front-face {
    height: 170px;
    object-fit: cover;
}