tampopo-client / app / src / main / res / drawable / in_call_background.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="@android:color/darker_gray" />
    <corners android:radius="8dp" />
</shape>