How to customize Collection View Selection Changed background color

Question

I have the following code to display some data:

<StackLayout Margin="15,0,15,5" BackgroundColor="Transparent">
        <CollectionView ItemsSource="{Binding DatabaseItems}" SelectionMode="Single" SelectionChanged="OnCollectionViewSelectionChanged"  BackgroundColor="Transparent">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <StackLayout>
                        <Frame BackgroundColor="#fff2d8" HorizontalOptions="Center" Margin="0,10,0,5" Padding="2" WidthRequest="350" CornerRadius="10">
                            <StackLayout BackgroundColor="#fff2d8">
                                <Label Text="{Binding Data1}" TextColor="Black" FontAttributes="Bold" HorizontalOptions="Center" Margin="0, 5, 0, 0" FontSize="20"/>
                                <Label Text="{Binding Data2}" TextColor="Black" Margin="10, 0, 0, 0" FontSize="15"/>
                                <Label Text="{Binding Data3}" TextColor="Black" Margin="10, 0, 0, 0" FontSize="15"/>
                                <Label Text="{Binding Data4}" TextColor="Black" Margin="10, 0, 0, 15" FontSize="15"/>
                            </StackLayout>
                        </Frame>
                    </StackLayout>    
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>
</StackLayout>

As you can see, I have a Selection Changed event, so everytime I click it, it does something.

The problem is, everytime I click it, the background is orange, and i'd like it to be other color, black or white for example. I've tried a couple things I've seen online but I can't make it work, at least not with this code.