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

#flash-container {
    text-align: center;
}

#number-display {
    font-size: 48px;
    margin: 20px;
}

#result {
    font-size: 24px;
    margin-top: 20px;
}

/* 白文字用のクラス */
.white-text {
    color: white;
}