*, *::before, *::after {
    box-sizing: border-box;
    font-family: Arial;
  }
  
  body {
    background-color: #333;
    display:flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-size: 7.5vmin;
   
  }
  
  #game-board {
    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{
    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;
        trasform: scale(0);
    }
}