*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    height: 100vh;
    background:linear-gradient(to right, #acb6e5,#74ebd5);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}
section{
    display: grid;
    grid-template-columns: repeat(4, 8rem);
    grid-template-rows: repeat(4, 8rem);
    grid-gap: 2rem;
    perspective: 800px;  /*for 3d effect- parent element should have it */
}
.card{
    position: relative;
     transform-style: preserve-3d;  /*so that actual element can preserve 3d effect */
    transition: all 2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    box-shadow: 0px 5px 15px rgba(0,0,0,0.2);
    /* transform: rotateY(180deg); for js where we just toggle it */
}
.face,.back{
    width: 100%;
    height: 100%;
    position: absolute;
    pointer-events: none;
}
.back{
    background-color: #fff;
    backface-visibility: hidden;
    cursor: pointer;
}
.toggleCard{
    transform: rotateY(180deg);
}