add ripple to month button

app/src/main/res/layout/activity_main.xml

@@ -17,6 +17,7 @@
 
     <TextView
         android:id="@+id/table_month"
+        style="@style/MonthStyle"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_toLeftOf="@+id/right_arrow"

app/src/main/res/values-v21/styles.xml

@@ -4,4 +4,8 @@
         <item name="android:background">?android:attr/selectableItemBackgroundBorderless</item>
     </style>
 
+    <style name="MonthStyle">
+        <item name="android:background">?android:attr/selectableItemBackground</item>
+    </style>
+
 </resources>

app/src/main/res/values/colors.xml

@@ -3,6 +3,6 @@
     <color name="colorPrimary">#3F51B5</color>
     <color name="colorPrimaryDark">#303F9F</color>
     <color name="colorAccent">#FF4081</color>
-    <color name="dark_grey_pressed_mask">#22000000</color>
+    <color name="dark_grey_pressed_mask">#11000000</color>
     <color name="lightGrey">#08000000</color>
 </resources>

app/src/main/res/values/styles.xml

@@ -22,6 +22,10 @@
         <item name="android:background">@drawable/button</item>
     </style>
 
+    <style name="MonthStyle">
+        <item name="android:background">@drawable/button</item>
+    </style>
+
     <style name="MyButton" parent="Widget.AppCompat.Button">
         <item name="android:textColor">@android:color/white</item>
         <item name="background">@drawable/button</item>