In the file, there is a section for the LPM clock. it will say LockScreen MLabelStyle#LockScreenLowPowerModeClockLabel Under that there is a heading font: $FONT_FAMILY etc. go to /home/user/.fonts (if not exist, create). Install system info app (from store) and go to config. > fonts to idnetify proper font name. Then in css replace font_family etc for "font name" (with inverted commas) eg. font: "Ostrich Sans" 10mm;