WordPress/src/main/res/drawable/reader_new_posts_bar_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="@color/color_primary_dark" />
    <corners android:radius="24dp" />

</shape>