Email customization CSS

Content

Hi there,

Do you know how to customize the notification email with CSS?

I have tried to add the CSS + HTML code into the notification alert, therefore editing the message into "manage the receiver and the message" (inside the interested notification allert) and then selecting HTML. However, once I have entered the code and run it, I receive an empty email or rather the code itself.

Actually, the output is a simple table that takes default values for its field regarding the confirmation of the registration to a course.

Do you know how to customize the notification alert email somehow?