I test the upgrade from an older version and with the new one, the "HourHalfBorderColor" property seems like not working : half hour <div> seems not to be generated.
Even I set it a color, even with the "CssOnly = false".
But it's writen "DayPilot Pro 8.0 and later versions only support CssOnly=true mode." in this page : https://doc.daypilot.org/calendar/cssonly-mode/
Is it possible to have different color for half hour line than hour line ?