User Manager has different style definitions for screen and for printer. You can see the printable form in Print preview mode (can be found under File > Print Preview in browsers main menu).
By default nothing is to be printed. People mostly print reports. So reports are the only thing that is visible in printing mode. There are different kinds of reports: user time/traffic reports over a period of time, single user report and user vouchers (print page). The last one is not really a report but could be treated as such, because it is meant to be printed.