*, *::after, *::before{
    box-sizing: border-box;
    font-family: serif;
}
body{
    background-color: rgb(41, 20, 49);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-size: 7.5vmin;
}
#game-board {
    /* --grid-size: 4;
    --cell-size: 20vmin;
    --cell-gap: 2vmin; */
display: grid;
grid-template-columns: repeat(var(--grid-size),var(--cell-size));
grid-template-rows: repeat(var(--grid-size),var(--cell-size));
background-color:#CCC;
gap: var(--cell-gap);
border-radius: 1vmin;
padding: var(--cell-gap);
position: relative;
}

.cell {
    background-color: #aaa;
    border-radius: 1vmin;
}

.tile{
    /* --x: 0;
    --y: 0;
    --background-lightness:80%;
    --text-lightness:20%; */
    position:absolute;
    display: flex;
    justify-content: center;
    align-items: center;
    width: var(--cell-size);
    height: var(--cell-size);
    background-color: red;
    border-radius: 1vmin;
    top: calc(var(--y) * (var(--cell-size) + var(--cell-gap)) + var(--cell-gap));
    left: calc(var(--x) * (var(--cell-size) + var(--cell-gap)) + var(--cell-gap));
    font-weight: bold;
    background-color: hsl(200, 50%, var(--background-lightness));
    color: hsl(200, 25%, var(--text-lightness));
    animation: show 200ms ease-in-out;
    transition: 100ms ease-in-out;
}

@keyframes show{
    0% {
        opacity: .5;
        transform: scale(0);
    }
}