Watch me segment CSS styles in a Guided Landing Page (in screenshots)

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.