Install / Add / Import font in mono (cross platform, open source .NET framework)

I'm setting up SubtitleEdit for my friend in their Linux Mint OS. I'm using the portable version of SubtitleEdit through mono as recommended here . Everything seems to be ok but the SubtitleEdit "menus font" (not the "subtitle font" from the settings) seems to fallback to a serif font that is IMO not really working (too small, hard to read, weird line-height, etc.). AFAIK SubtitleEdit doesn't allow you to set the "menus font". I believe that, if I add the right font in the mono framework, SubtitleEdit will be able to use it and won't fallback to the serif font. How can I add or install a font in mono? ty SubtitleEdit Screenshot with default font SubtitleEdit Screenshot through mono with fallback font