Android Studio, caldroid (calendar) library. How to change the background?

Question

Android

Let me know who has come across. How can I change the background and text color of the entire calendar? Here is the library https://github.com/willowtreeapps/Caldroid
I'm trying this line,

args.putInt(CaldroidFragment._BACKGROUND_FOR_DATETIME_MAP,R.color.caldroid_background);

But it doesn't come out.