WPF - ContentPresenter won't display Content - wpf

Question

I am trying to create a container-like component. It uses the MaterialDesign Card as a container, places a title in it and allows space for Content.
<ContentControl
x:Class="Client.Components.AisCard"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="450"
d:DesignWidth="800">
<materialDesign:Card
Margin="0,0,20,0"
Padding="20,20,20,30">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock
Grid.Row="0"
Text="Opmerkingen"
Style="{StaticResource MaterialDesignHeadline5TextBlock}"
FontWeight="Medium"
Margin="0,0,0,10" />
<ContentPresenter Grid.Row="1" />
</Grid>
</materialDesign:Card>
</ContentControl>
Then, I call the Component in a view and attempt to fill its Content:
<Components:AisCard
Grid.Column="0"
Grid.Row="0">
<TextBlock Text="Hello World" />
</Components:AisCard>
The result looks like this:
I expected it to look like this:
Maybe I have misunderstood the way that a ContentPresenter works. Maybe using a Component inside of a Component is not the way to go. Could anyone offer some form of assistance in the matter?

Answer 1

The TextBlock replaces the Card, because both just set the Content property. You would have to declare the Card as part of a ControlTemplate:
<ContentControl
x:Class="Client.Components.AisCard"
...>
<ContentControl.Template>
<ControlTemplate TargetType="ContentControl">
<materialDesign:Card
Margin="0,0,20,0"
Padding="20,20,20,30">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock
Grid.Row="0"
Text="Opmerkingen"
Style="{StaticResource MaterialDesignHeadline5TextBlock}"
FontWeight="Medium"
Margin="0,0,0,10" />
<ContentPresenter Grid.Row="1" />
</Grid>
</materialDesign:Card>
</ControlTemplate>
</ContentControl.Template>
</ContentControl>