#dragDropArea {
    border: 2px dashed #007bff;
    border-radius: 10px;
    padding: 40px;
    max-width: 500px;
    margin: 20px auto;
    background-color: #f0f4f8;
    cursor: pointer;
    position: relative;
    color: #333;
    transition: background-color 0.3s;
    text-align: center;
}
#dragDropArea:hover { background-color: #e1e9f3; }

#dragDropArea input[type="file"] {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    opacity: 0;
    cursor: pointer;
    z-index: 10;
}

.upload-icon { font-size: 50px; margin-bottom: 15px; }

#fileName { margin-top: 10px; font-weight: bold; color: #333; }

#options { margin-top: 20px; display: none; }

#progressBar { width: 100%; background-color: #ddd; border-radius: 5px; height: 15px; margin-top: 10px; }
#progressBarFill { width: 0%; height: 100%; background-color: #28a745; border-radius: 5px; transition: width 0.4s; }

#successMessage { display: none; color: green; font-weight: bold; margin-top: 10px; }

#downloadLink { display: none; background-color: #007bff; color: white; padding: 8px 16px; border-radius: 5px; text-decoration: none; margin-top: 10px; }

#addNumbersBtn {
    background-color: #007bff;
    color: white;
    padding: 8px 20px;
    border-radius: 5px;
    border: none;
    cursor: pointer;
}
#addNumbersBtn:hover { background-color: #0056b3; }