app/src/main/res/drawable/nav_background_curved.xml
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<solid android:color="@color/white" />
<corners
android:topLeftRadius="35dp"
android:topRightRadius="35dp"/>
</shape>