Android how to change Caldroid calendar background for months

Question

Im trying do some changes in Caldroid calendar background. Here is libary for Caldroid calendar: https://github.com/roomorama/Caldroid

Firs i put dark theme by following documentation, here is code for dark theme:

<!-- Dark theme. -->
    <style name="CaldroidDefaultDark" parent="CaldroidDefault">
        <item name="styleCaldroidViewLayout">@style/CaldroidDefaultDarkCalendarViewLayout</item>
        <item name="styleCaldroidMonthName">@style/CaldroidDefaultDarkMonthName</item>
        <item name="styleCaldroidNormalCell">@style/CaldroidDefaultDarkNormalCell</item>
        <item name="styleCaldroidSquareCell">@style/CaldroidDefaultDarkSquareCell</item>
        <item name="styleCaldroidGridView">@style/CaldroidDefaultDarkGridView</item>
    </style>

    <style name="CaldroidDefaultDarkCalendarViewLayout">
        <item name="android:background">@android:color/black</item>
    </style>

    <style name="CaldroidDefaultDarkMonthName" parent="CaldroidDefaultMonthName">
        <item name="android:textColor">@color/caldroid_white</item>
    </style>

    <style name="CaldroidDefaultDarkGridView" parent="CaldroidDefaultGridView">
        <item name="android:background">@color/caldroid_middle_gray</item>
    </style>

    <style name="CaldroidDefaultDarkCell" parent="CaldroidDefaultCell">
        <item name="android:textColor">@color/cell_text_color_dark</item>
        <item name="android:background">@drawable/cell_bg_dark</item>
    </style>

    <style name="CaldroidDefaultDarkNormalCell" parent="CaldroidDefaultDarkCell">
        <item name="android:padding">5dp</item>
    </style>

    <style name="CaldroidDefaultDarkSquareCell" parent="CaldroidDefaultDarkCell" />

Now i get this:

My question is how to change black background dates to be blue and grey dates to be lets say green.