How to download the complete html of emails with python using imap

Goal:

Getting the Html of an email looking exactly as in the mailbox saved as.html

Explanation: I am using Python and IMAP to download email and get the HTML content with .get_content_payload(text/HTML) but when I save it and open it, it doesn't look like the mail content as shown in the mailbox.

I tried writing an HTML file with mail_html but, it doesn't work out quite well as the CSS is missing the whole HTML email looks terrible. I want it to download along with other page assets. And here I need your help.

mail = imaplib.IMAP4_SSL(SERVER)
    mail.login(EMAIL, PASSWORD)
    mail.select(f'{TARGET}')
    status, data = mail.search(None, 'ALL')
    mail_ids = []
    for block in data:
        mail_ids += block.split()
    for mail_id in mail_ids:
        status, data = mail.fetch(mail_id, '(RFC822)')
        print("BODY ENDS")
        for response_part in data:
            if isinstance(response_part, tuple):
                message = email.message_from_bytes(response_part[1])
                mail_from = message['from']
                mail_subject = message['subject']
                # if it is multi-part message separate first
                if message.is_multipart():
                    mail_content = ''
                    mail_html = ' '
                    for part in message.get_payload():
                        # Get all parts of the message
                        if part.get_content_type() == 'text/plain':
                            mail_content += part.get_payload()
                        if message.get_content_type() == "text/html":
                            mail_html + part.get_payload()