Fixed fab color in dark mode

app/src/main/res/drawable/subscribe_button_background.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <selector xmlns:android="http://schemas.android.com/apk/res/android" android:color="#000000">
     <item android:color="@color/colorSuccessAccent" android:state_selected="true" />
-    <item android:color="@color/colorAccent" />
+    <item android:color="?attr/colorAccent" />
 </selector>