Font-face in plugin UI


I’m designing a Figma Plugin and want to use a custom font in my plugin UI. I don’t intend on modifying nodes with this font at all so I don’t care if it’s available for that purpose. I’ve tried doing this the normal way: adding an otf file to my codebase then creating a font-face in my css linking to that file. However, when I use the newly created font-family, the font isn’t loading in the UI. I’m fairly new to figma plugins so I’m not sure what the issue is.