Injecting css into chat?

besides inserting styles directly into the element e.g. style="color:red". Is there a way to inject styles for theming purposes?  I would like to build template literal html form with css/sass.  e.g.   <div class="${containerStyle}">Internal stuff</div>. (Typescript Template literal). I would need to load the style data into something similar to the header style element <style>. I have the html literal working, just need the css/sass etc. 

The Power Cards API Script was designed for this (for styling output into chat, that is, not necessarily the specific technique your using). It has an active thread you can ask for help.

There isn't a way to style API text output other than with inline styling.  Note also that the inline styles get filtered so not everything works.

Well that's poo poo.  :P 

Second, question, is there documentation or a list of styles that are filtered? Thus I can stay away from them.

Nope.  Most normal stuff works.  Most function style stuff doesn't.  It's trial and error at its finest... 

Thank you for the info. I sincerely appreciate it!