\defaultfontfeatures[jetbrainsmono-extralight]
   {Extension=.otf,
    UprightFont=JetBrainsMono-ExtraLight,
    ItalicFont=JetBrainsMono-ExtraLightItalic,
    BoldFont=JetBrainsMono-Medium,
    BoldItalicFont=JetBrainsMono-MediumItalic,
    Contextuals=AlternateOff
}