Telegram / TMessagesProj / src / main / res / drawable-v21 / regbtn_states.xml

<?xml version="1.0" encoding="UTF-8"?>

<ripple xmlns:android="http://schemas.android.com/apk/res/android"
        android:color="#ff1c94cf">
    <item android:drawable="@drawable/regbtn2"/>
</ripple>