Make sense? I'm sure it does.
But you might wonder why you can't include the <style>, or a remote <link> for that matter,[1] directly in the mktoText area, like so:
Test and you'll see why Text {{my.tokens}} are necessary. ☺
Another take
A twist on the same approach gives something superior, if a little strange(r).
Set up just 2 tokens, one for opening <style> and one for the closing </style>, at the top level of Marketing Activities. Then you can reuse those tokens everywhere and write CSS directly in the mktoText.
Notes
[1] You can include a <link> tag in the {{my.token}}, of course. I'm not saying you can't use external stylesheets, just that they need to be passed in via tokens.