Small behavior improvement

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

@@ -338,7 +338,7 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_marginStart="12dp"
-                android:background="@null"
+                android:background="?android:attr/selectableItemBackgroundBorderless"
                 android:contentDescription="@string/title_legend_default_color"
                 app:layout_constraintBottom_toBottomOf="@id/btnColor"
                 app:layout_constraintStart_toEndOf="@id/vwColor"

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

@@ -145,7 +145,7 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_marginStart="12dp"
-                android:background="@null"
+                android:background="?android:attr/selectableItemBackgroundBorderless"
                 android:contentDescription="@string/title_legend_default_color"
                 app:layout_constraintBottom_toBottomOf="@id/btnColor"
                 app:layout_constraintStart_toEndOf="@id/vwColor"

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

@@ -508,7 +508,7 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_marginStart="12dp"
-                android:background="@null"
+                android:background="?android:attr/selectableItemBackgroundBorderless"
                 android:contentDescription="@string/title_legend_default_color"
                 app:layout_constraintBottom_toBottomOf="@id/btnColor"
                 app:layout_constraintStart_toEndOf="@id/vwColor"