body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    text-align: center;
}

#game-board {
    display: grid;
    grid-template-columns: repeat(5, 100px);
    grid-template-rows: repeat(5, 100px);
    gap: 10px;
    margin: 20px auto;
}

#game-board div {
    background-color: #fff;
    border: 2px solid #000;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    position: relative;
}

#game-board div input {
    width: 60px;
    height: 60px;
    font-size: 24px;
    text-align: center;
}

.hidden input {
    display: block;
}

#start-button, #confirm-button {
    margin: 20px;
    padding: 10px 20px;
    font-size: 18px;
}

#timer, #score, #penalty {
    font-size: 18px;
    margin: 10px;
}

input {
    transition: border-color 0.2s, background-color 0.2s;
}