.dem-ngay-online-container {
    background-color: #f9f9f9;
    border: 1px solid #ddd;
    padding: 25px;
    border-radius: 8px;
    max-width: 500px;
    margin: 20px auto;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: #333;
}

/* Định dạng chuẩn cho tiêu đề: căn giữa, in đậm, màu xanh lá và có đường kẻ ngang tách biệt */
.dem-ngay-online-container .dem-ngay-tieu-de {
    text-align: center;
    color: #1b6b36;
    margin-bottom: 25px;
    font-size: 1.3em;
    font-weight: bold;
    border-bottom: 1px solid #dcdcdc;
    padding-bottom: 15px;
    letter-spacing: 0.5px;
}

.dem-ngay-online-group {
    margin-bottom: 18px;
    display: flex;
    align-items: center;
}

.dem-ngay-online-group label {
    flex: 0 0 120px;
    margin-right: 15px;
    font-weight: bold;
    color: #555;
    font-size: 1.1em;
}

.dem-ngay-online-datepicker {
    flex-grow: 1;
    padding: 10px 12px;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 1em;
    box-sizing: border-box;
    cursor: pointer;
}

.dem-ngay-online-group.checkbox-group {
    justify-content: flex-start;
    margin-top: 25px;
    margin-bottom: 30px;
}

.dem-ngay-online-group.checkbox-group input[type="checkbox"] {
    width: 20px;
    height: 20px;
    margin-right: 10px;
    cursor: pointer;
}

.dem-ngay-online-group.checkbox-group label {
    flex: unset;
    margin-right: 0;
    font-weight: normal;
    font-size: 1em;
    cursor: pointer;
}

.dem-ngay-online-button {
    display: block;
    width: 100%;
    padding: 12px 20px;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1.1em;
    font-weight: bold;
    transition: background-color 0.3s ease, transform 0.1s ease;
    margin-bottom: 25px;
}

.dem-ngay-online-button:hover {
    background-color: #2980b9;
    transform: translateY(-1px);
}

.dem-ngay-online-result-group {
    text-align: center;
    margin-top: 20px;
    margin-bottom: 15px;
    font-size: 1.2em;
    font-weight: bold;
    color: #4a4a4a;
    display: flex;
    align-items: center;
    justify-content: center;
}

.dem-ngay-online-result-group label {
    margin-right: 10px;
    color: #333;
}

.dem-ngay-online-result {
    color: #e74c3c;
    font-size: 1.5em;
}

.dem-ngay-online-message {
    margin-top: 20px;
    padding: 12px;
    border-radius: 5px;
    font-weight: bold;
    text-align: center;
    font-size: 0.95em;
    border: 1px solid transparent;
}

.dem-ngay-online-message.error {
    background-color: #ffe0e0;
    color: #c0392b;
    border-color: #e74c3c;
}

.dem-ngay-online-message.success {
    background-color: #e0ffe0;
    color: #27ae60;
    border-color: #2ecc71;
}

.ui-datepicker {
    font-size: 0.9em;
}
.ui-datepicker td span, .ui-datepicker td a {
    text-align: center;
    padding: .2em .3em;
}