Including custom CSS with a page Header Action?

[scottw-finao]

Package

Actions

Package Version

v3

How can we help you?

I want to add a modal tied to a button in the header that pops up a form. One of the options on the form includes an ability to select a font for generating text. If possible, I would like to format the option text with the font face itself.
I know how to include the font in a @font-face in css, but I'm not sure how to inject the CSS into the modal/action. (I would like to be able to use this tool portably on multiple other admin pages and widgets, so including the css with the form in the action modal would be necessary)