:root{
    --w: calc(70vw / 6);
    --h: calc(70vh / 4);
}

*{
    transition: all 0.5s;
}

body{
    padding: 0;
    margin: 0;
    -webkit-perspective: 1000;
    background: powderblue;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    font-family: calibri;

}

div{
    display: inline-block;
}

.area-tarjeta, .tarjeta, .cara{
    cursor: pointer;
    width: var(--w);
    min-width: 80px;
    height: var(--h);
}

.tarjeta{
    position: relative;   
    transform-style:  preserve-3d;
    animation:  iniciar 5s;
}


.cara{
    position: absolute;
    backface-visibility: hidden;
    box-shadow: inset 0 0 0 5px white;
    font-size: 500%;
    display: flex;
    justify-content: center;
    align-items: center;
}

.trasera{
    background-color: lightcyan;
    transform: rotateY(180deg);
}

.superior{
    background: linear-gradient(orange, darkorange);
}


.nuevo-juego{
    cursor: pointer;
    background: linear-gradient(orange, darkorange);
    padding: 20px;
    border: 5px solid white;
    border-radius: 50px;
}

@keyframes iniciar {
    20%, 90%{
        transform:  rotateY(180deg);
    }
    0%, 100%{
        transform: rotate(0deg);
    }
}