* {
    margin: 0;
    padding: 0;
}

#game div {
    transition: border 1s ease;
    border: solid thin transparent;
}

#game.gridon div {
    border-color: black;
}

#game {
    display: grid;
    grid-template-columns: repeat(25, 1fr);
    grid-template-rows: repeat(25, 1fr);
    width: 100vmin;
    height: 100vmin;
}

.snake {
    background: green;
}

.gameover .snake {
    background: red;
}

.food {
    background: purple;
}