justify-content disappears inside mail Django HTML-CodePudding

I created a function in Django to sending activation mails. Now I am styling mail, but the problem is that the justify-content: center; property inside header tag disappears in the mail message. I mean margin-bottom: 20px; display: flex; font-size: 20px; options exist there but justify-content not.

Finally text inside header is on the left side of the mail but should be in the center.

def send_activation_email(user, request):
    email_subject = "..."
    email_body = render_to_string('activate.html', {
        ...
    })

    email=EmailMessage(subject=email_subject, body=email_body, from_email=EMAIL_FROM_USER, to=[user.email])
    email.content_subtype='html'
    email.send()

<body style="padding: 30px; background-color: #f0f0f0;">
        <div style="background-color: white;
            padding: 30px;
            border-radius: 10px;
            box-shadow: rgba(60, 64, 67, 0.3) 0px 1px 2px 0px,
            rgba(60, 64, 67, 0.15) 0px 1px 3px 1px;">
                <header style="margin-bottom: 20px; display: flex; justify-content: center; font-size: 20px;">...</header>
        </div>
    </body>

Mail looks like this:

and inside code there not exit the justify-content property:

CodePudding user response：

CSS support depends on the email provider.

https://www.caniemail.com/features/css-justify-content/

You can use margin to center the content.

margin: 0 auto;