* {
    margin: 0;
    padding: 0;
}
body {
    background-color: #2ed573;
}
#game {
    margin: 0 auto;
    position: absolute;
    left: 50%;
    top: 50%;
    -webkit-transform: translate(-50%, -50%);
    height: 800px;
    width: 800px;
    display: grid;
    grid-template-rows: repeat(10, 1fr);
    grid-template-columns: repeat(10, 1fr);
    border: 3px solid black;
}