:root {
    --grid-cols: 1;
    --grid-rows: 1;
}

#container {
    display: grid;
    width: 720px;
    height: 720px;
    grid-gap: 0;
    grid-template-rows: repeat(var(--grid-rows), 1fr);
    grid-template-columns: repeat(var(--grid-cols), 1fr);
    border: 1px solid #000;
}

.grid-item {
    padding: 0;
    margin: 0;
    border: 0px solid #ddd;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
}