Glad to help, but it’s not a current feature of the plugin. As far as I know all the fonts and styles are provided wholesale by the Prism.js or Highlight.js scripts. The Prismatic plugin simply loads the scripts on the page, without adding any special font or other styles.
Best advice would be to ask in the Prism.js or Highlight.js support forum, maybe someone with more knowledge about the scripts can shed some light on how to override fonts or whatever is required.
I hope this helps, let me know if I can provide any further information.