style.css

@import url('https://fonts.googleapis.com/css2?family=Roboto+Slab:wght@200&display=swap');
:root{
    --card-width-lg:157px;
    --card-height-lg:220px;

    --card-width-sm:120px;
    --card-height-sm:168px;

    --num-cards:4;

    --card-horizontal-space-lg: 100px;
    --card-horizontal-space-sm: 50px;

    --badge-bg-color:darkgrey;
    --primary-color: black;
    --secondary-color: #ffffff;

    --primary-font: 'Roboto Slab', serif;;
}
html {
    --u:  2.25vmin;
    --c1: #83b0e3;
    --c2: #6c91bb;
    --c3: #4d6887;
    --gp: 50%/calc(var(--u) * 5) calc(var(--u) * 10);
    --bp: calc(var(--u) * -2.5) calc(var(--u) * -5);
    height: 100vh;
    --bg:
            radial-gradient(circle at 50% 25%, var(--c2)  15%, #fff0 30% 100%) var(--gp),
            conic-gradient(from 270deg at 34% 46%, var(--c2) 0 12.5%, #fff0 0 100%) var(--gp),
            conic-gradient(from 45deg at 66% 46%, var(--c2) 0 12.5%, #fff0 0 100%) var(--gp),
            conic-gradient(from 180deg at 50% 80%, var(--c2) 0 12.5%, #fff0 0 100%) var(--gp),
            conic-gradient(from 135deg at 50% 80%, var(--c2) 0 12.5%, #fff0 0 100%) var(--gp),
            conic-gradient(from 0deg at 0% 20%, var(--c2) 0 12.5%, #fff0 0 100%) var(--gp),
            conic-gradient(from -45deg at 100% 20%, var(--c2) 0 12.5%, #fff0 0 100%) var(--gp),
            linear-gradient(180deg, var(--c2) 0 4.5%, #fff0 0 45.25%, var(--c2) 0 50%, #fff0 0% 100%) var(--gp),
            radial-gradient(circle at 50% 25%, #fff0 0 25%, var(--c2) 26% 32%, #fff0 0 100%) var(--gp),
            linear-gradient(165deg, var(--c3) 15%, var(--c1) 44%, #fff0 0 100%) var(--gp),
            linear-gradient(180deg, var(--c1) 50%, #fff0 0 100%) var(--gp);
    background:
            var(--bg),
            var(--bg);
    background-position:
            var(--bp), var(--bp), var(--bp), var(--bp), var(--bp), var(--bp), var(--bp), var(--bp), var(--bp), var(--bp), var(--bp),
            0 0, 0 0, 0 0, 0 0, 0 0, 0 0, 0 0, 0 0, 0 0, 0 0, 0 0;
}

body{

    background-color: rgba(256,256,256,0.6);
    height:100vh;
    font-family: var(--primary-font);
}

main{
    height: 55%;
    display: flex;
    justify-content: center;

}

.card-container{
    position: relative;
    height:100%;
    width:calc(var(--card-width-lg) * (var(--num-cards) / 2) + var(--card-horizontal-space-lg));
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-rows: 1fr 1fr;
    grid-template-areas: "a b"
                         "c d";

}

.card-pos-a{
    grid-area: a;
    /* background-color: gray; */
}
.card-pos-b{
    grid-area: b;
    /* background-color: goldenrod; */
}
.card-pos-c{
    grid-area: c;
    /* background-color: rosybrown; */
}
.card-pos-d{
    grid-area: d;
    /* background-color: darkcyan; */
}
.card-pos-a, .card-pos-b,.card-pos-c,.card-pos-d{
    display:flex;
    justify-content: center;
    align-items: center;
}

.card{
    position:absolute;
    height:var(--card-height-lg);
    width:var(--card-width-lg);
    perspective: 1000px;
    cursor: pointer;
    transition: transform 0.6s ease-in-out
}
.card-inner{
    position: relative;
    width:100%;
    height:100%;
    text-align: center;
    transition: transform 0.8s;
    transform-style: preserve-3d;
}
.card-inner:hover{
    scale: 1.1;
}
.card-front, .card-back{
    position:absolute;
    width:100%;
    height:100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
}
.card-img{
    height:100%;
}
.card-back{
    transform: rotateY(180deg);
}
.card-inner.flip-it{
    transform: rotateY(180deg);
}
header{
    display: flex;
    flex-direction: column;
    margin-bottom:10px;
}
.header-title-container{
    display: flex;
    justify-content: center;
}
.header-round-info-container{
    display: flex;
    justify-content: space-evenly;
}
.current-status{
    font-size:1.5rem;
    text-align: center;
}


.header-status-info-container,
.header-button-container,
.header-score-container,
.header-round-container,
.header-img-container{
    display: flex;
    justify-content: center;
    align-items: center;
}

.header-score-container,
.header-round-container,
.header-img-container
{
    width: 150px;
}
.header-img{
    height: 75px;
    border-radius: 5px;
    border: 1px solid black;
    padding: 5px;
    box-shadow: 0 4px 8px 0 rgba(0,0,0,0.2);
    transform: rotate(-3deg);
}
.badge{
    background-color: var(--badge-bg-color);
    color: var(--secondary-color);
    padding: 2px 10px 3px;
    border-radius: 15px;
}
.game-play-button-container{
    width:150px;
    height:70px;
}

#playGame {
    appearance: none;
    background-color: transparent;
    border: 2px solid #1A1A1A;
    border-radius: 15px;
    box-sizing: border-box;
    color: #3B3B3B;
    cursor: pointer;
    display: none;
    font-family: var(--primary-font);
    font-size: 16px;
    font-weight: 600;
    line-height: normal;
    margin: 0;
    min-height: 60px;
    min-width: 0;
    outline: none;
    padding: 16px 24px;
    text-align: center;
    text-decoration: none;
    transition: all 300ms cubic-bezier(.23, 1, 0.32, 1);
    user-select: none;
    -webkit-user-select: none;
    touch-action: manipulation;
    width: 100%;
    will-change: transform;
    animation: game-play-button-fade-in 10s 1;
}

#playGame:disabled {
    pointer-events: none;
}

#playGame:hover {
    color: #fff;
    background-color: #1A1A1A;
    box-shadow: rgba(0, 0, 0, 0.25) 0 8px 15px;
    transform: translateY(-2px);
}

#playGame:active {
    box-shadow: none;
    transform: translateY(0);
}

@keyframes game-play-button-fade-in{
    from{opacity: 0;}
    to{opacity: 1;}
}


.card.shuffle-left{
    transform: translateX(300px) translateY(40px);
}
.card.shuffle-right{
    transform: translateX(-350px) translateY(-40px);
}
.card.fly-in{
    transform: translateY(-1000px) translateX(-600px) rotate(45deg);
}

@media screen and (max-width:600px){
    .card{
        width: var(--card-width-sm);
        height: var(--card-height-sm);
    }
    .card-container{
        width: calc(var(--card-width-sm) * (var(--num-cards)/2) + var(--card-horizontal-space-sm));
    }
    main{
        height:50%;
    }
    .current-status{
        font-size:1.2rem;
    }
    .game-play-button-container{
        width: 120px;
        height: 40px;
    }
    #playGame{
        padding: 6px 8px;
        font-size:12px;
        min-height:40px;
    }
    .header-img{
        height:55px;
    }
}