tachiyomi/app/src/main/res/layout/navigation_view_group.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="?attr/listPreferredItemHeightSmall"
    android:background="?attr/colorPrimary"
    android:elevation="2dp"
    android:gravity="center_vertical"
    android:orientation="horizontal"
    android:paddingStart="?attr/listPreferredItemPaddingStart"
    android:paddingEnd="?attr/listPreferredItemPaddingEnd">

    <TextView
        android:id="@+id/title"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:ellipsize="end"
        android:maxLines="1"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1"
        android:textColor="?attr/colorOnPrimary"
        tools:text="Header" />

    <ImageView
        android:id="@+id/expand_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:tint="?attr/colorOnPrimary" />

</LinearLayout>