Apply a particular style to all child elements of a Xamarin.Forms element

I have a Style with target type Grid. I want all Entry child elements within a grid of this style to automatically acquire a particular style.

I've had a look at these:

Styling nested elements in WPF

Apply Style to all child-elements of specific type

The only solution appears to be setting Resources within the parent Style, so this is what I've done:

<Style x:Key="BuggyGrid" TargetType="Grid">
    <!-- bunch of property setters -->
    <Style.Resources>
        <Style TargetType="Entry">
            <Setter Property="FontFamily" Value="Arial" />
        </Style>
    </Style.Resources>
</Style>

However, I get a build error: "No property, bindable property, or event found for 'Resources'".

Why do I get this error?

I'm using Xamarin.Forms 2.3.2.