Fix manga info expand button background

app/src/main/res/layout-sw720dp/manga_info_header.xml

@@ -238,6 +238,8 @@
             android:layout_marginBottom="-4dp"
             android:paddingStart="0dp"
             android:paddingEnd="0dp"
+            android:background="@android:color/transparent"
+            android:contentDescription="@string/manga_info_expand"
             android:src="@drawable/ic_expand_more_24dp"
             app:layout_constraintBottom_toBottomOf="@id/manga_summary_text"
             app:layout_constraintEnd_toEndOf="parent"
@@ -251,6 +253,8 @@
             android:layout_height="wrap_content"
             android:paddingStart="8dp"
             android:paddingEnd="8dp"
+            android:background="@android:color/transparent"
+            android:contentDescription="@string/manga_info_collapse"
             android:src="@drawable/ic_expand_less_24dp"
             android:visibility="gone"
             app:layout_constraintEnd_toEndOf="parent"

app/src/main/res/layout/manga_info_header.xml

@@ -249,6 +249,8 @@
             android:layout_marginBottom="-4dp"
             android:paddingStart="0dp"
             android:paddingEnd="0dp"
+            android:background="@android:color/transparent"
+            android:contentDescription="@string/manga_info_expand"
             android:src="@drawable/ic_expand_more_24dp"
             app:layout_constraintBottom_toBottomOf="@id/manga_summary_text"
             app:layout_constraintEnd_toEndOf="parent"
@@ -262,6 +264,8 @@
             android:layout_height="wrap_content"
             android:paddingStart="8dp"
             android:paddingEnd="8dp"
+            android:background="@android:color/transparent"
+            android:contentDescription="@string/manga_info_collapse"
             android:src="@drawable/ic_expand_less_24dp"
             android:visibility="gone"
             app:layout_constraintEnd_toEndOf="parent"