added new font size variables to headers in typography stylesheet
added new font size variables to headers in typography stylesheet

praneybehl/utool-io,uTool-io/utool-io,praneybehl/utool-io,amazingBastard/minimal-agency,amazingBastard/minimal-agency,uTool-io/utool-io,withpulp/minimal-agency,withpulp/minimal-agency