sample_styled.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="?android:windowBackground"
    android:clipChildren="false"
    >

  <androidx.recyclerview.widget.RecyclerView
      android:id="@+id/sample_styled_recyclerview"
      android:layout_width="0dp"
      android:layout_height="0dp"
      android:clipToPadding="false"
      android:paddingBottom="8dp"
      android:paddingTop="8dp"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent"
      tools:listitem="@layout/data_item"
      />

  <com.reddit.indicatorfastscroll.FastScrollerView
      android:id="@+id/sample_styled_fastscroller"
      style="@style/Widget.FastScrollSample.FastScroller.Floating"
      android:layout_width="32dp"
      android:layout_height="wrap_content"
      android:layout_marginEnd="8dp"
      android:paddingBottom="8dp"
      android:paddingTop="8dp"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintTop_toTopOf="parent"
      />

  <com.reddit.indicatorfastscroll.FastScrollerThumbView
      android:id="@+id/sample_styled_fastscroller_thumb"
      style="@style/Widget.FastScrollSample.FastScrollerThumb.Colorful"
      android:layout_width="40dp"
      android:layout_height="0dp"
      android:layout_marginEnd="16dp"
      app:layout_constraintBottom_toBottomOf="@+id/sample_styled_fastscroller"
      app:layout_constraintEnd_toStartOf="@+id/sample_styled_fastscroller"
      app:layout_constraintTop_toTopOf="@+id/sample_styled_fastscroller"
      />

</androidx.constraintlayout.widget.ConstraintLayout>