#game-board {
    display: grid;
    grid-gap: 1px;
    background-color: #ccc;
}

.cell {
    width: 30px;
    height: 30px;
    background-color: #eee;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    user-select: none;
}

.cell.revealed {
    background-color: #ddd;
}

.cell.mine {
    background-color: red;
}

.cell.flagged {
    background-color: yellow;
}