Jquery SimpleEventCalendar - how to make static day names and variable numbers?

Question

JavaScript

Hello.
In general, the site needs a calendar. I settled on this choice - the most suitable.
https://github.com/philipehsing/jQuery.Simple-Even...
-----------------------
The author's screenshot shows that if, let's say , Monday fell on the previous month, and the beginning of this month from Wednesday - then the days are filled with gray numbers of the previous month.
It is not implemented in the source code. In the source codes, it turns out that the numbers from 1 to 30 are statically arranged, and depending on the day of the week, the arrangement of the days of Mon-Sun changes.

Actually, a fix is ​​needed so that the days of the week Mon-Sun are statically located, and the arrangement of the numbers of the month changes.
I would be very grateful for your help.