body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding: 0;
}

.container {
    width: 80%;
    margin: 0 auto;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

button {
    background-color: #007bff;
    color: #fff;
    border: none;
    padding: 10px 20px;
    cursor: pointer;
    border-radius: 5px;
    margin-top: 10px;
}

button:hover {
    background-color: #0056b3;
}

.changed-cell {
    background-color: #fff7c0 !important;
    /* 옅은 노랑색 */
}