Printout or view a shcedule - visual enhancement

[liquid]

I suggest (please) to divide days with bolder or thicker lines. For me, it would enhance clarity when viewing or printing a schedule, both in printable and viewable versions.

[Volker Dirr]

Thank you for suggesting. It is already in the TODO (#180). There are currently other more important things i want to code. So it will take some some.