simple_vertical_calendar library Null safety
- DayHeaderStyle is the styling class for Day widget.
- DayOfWeekHeaderStyle is the styling class for Day of the Week widget.
- HeaderStyle is the styling class for each month header of the widget.
- HeaderWidget is the widget for building Month Header section of the calendar.
- SimpleVerticalCalendar is the widget for scrollable vertical calendar that is similar to the one in AirBnB.