app.css

  
  /* 
  CARD FLIP ANIMATIONS ADAPTED FROM DAVID WALSH BLOG:
  https://davidwalsh.name/css-flip 
  */

  #game .flip-container {
    perspective: 1000px;
    width: 15%;
    height: 200px;
    margin: 10px;
    display: inline-block;
}  

.flip-container .flipper {
    width: 100%;
    height: 100%;
    display: inline-block;
}  

.flipper .front, .back {
    border: 1px solid black;
    width: 100%;
    height: 100%;
    margin: 0;
    display: inline-block;
    backface-visibility: hidden;
    position: absolute; 
    top: 0;
    left: 0;
}

.flipper {
    transition: .6s;
    transform-style: preserve-3d;
    position: relative;
}

.front {
    z-index: 2;   
}
 
 .back {
    transform: rotateY(180deg);
} 

.back img {
    height: 100%;
    width: 100%;
}