MonCalc / app / src / main / res / drawable / custom_spinner_dropdown.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <stroke
        android:width="1dp"
        android:color="#ffffff" />
    <solid android:color="#ffffff" />
    <corners android:radius="4dp" />

</shape>