The content of the comment block of a subscription is embedded as a table in the email output, so you won't be able to include CSS in a <style> tag as expected.
An option is to use an inline style attribute, which is applied to the email content. For example:
The content of the comment block of a subscription is embedded as a table in the email output, so you won't be able to include CSS in a
<style>
tag as expected.An option is to use an inline style attribute, which is applied to the email content. For example:
This page can help with conversion from a CSS block to inline styles so you don't have to do it by hand.