body {
    background: #eee;
    display: flex;
}

#lobby {
    margin-left: 50vw;
    margin-top: 50vh;
    transform: translate(-50%, -50%);
}

#game {
    flex-wrap: wrap;
    align-content: center;
    margin:auto;
}

#board {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

#end {
    position: absolute;
    justify-content: center;
    z-index: 200;
}

#endScreenBtn {
    margin-left: 50vw;
    margin-top: 50vh;
    transform: translate(-50%, -50%);
}

.card {
    position: relative;
    width: 20vw;
    height: 20vw;
    margin: 2px;
}

.content {
    position: absolute;
    width: 100%;
    height: 100%;
    box-shadow: 0 0 15px rgba(0,0,0,0.1);

    transition: transform 1s;
    transform-style: preserve-3d;
    z-index: 1;
}

.flipped .content {
    transform: rotateY( 180deg ) ;
    transition: transform 0.5s;
}

.front,
.back {
    position: absolute;
    height: 100%;
    width: 100%;
    background: white;
    line-height: 300px;
    color: #03446A;
    text-align: center;
    font-size: 60px;
    border-radius: 5px;
    backface-visibility: hidden;
}

.front {
    transform: rotateY( 180deg );
}
.back {
    background: #03446A;
    color: white;
}

img {
    width:100%;
    height:100%;
    position: absolute;
    top: 0;
    left: 0;
}