Flow.Launcher/Flow.Launcher.Avalonia/Views/Controls/CardGroup.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:controls="using:Flow.Launcher.Avalonia.Views.Controls"
             x:Class="Flow.Launcher.Avalonia.Views.Controls.CardGroup"
             x:DataType="controls:CardGroup"
             mc:Ignorable="d">

    <UserControl.Styles>
        <Style Selector="controls|CardGroup">
            <Setter Property="Template">
                <ControlTemplate TargetType="controls:CardGroup">
                    <Border Background="{DynamicResource CardBackgroundFillColorDefaultBrush}"
                            BorderBrush="{DynamicResource CardStrokeColorDefaultBrush}"
                            BorderThickness="1"
                            CornerRadius="5">
                        <ItemsPresenter ItemsPanel="{TemplateBinding ItemsPanel}" />
                    </Border>
                </ControlTemplate>
            </Setter>
            <Setter Property="ItemsPanel">
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Vertical" />
                </ItemsPanelTemplate>
            </Setter>
        </Style>
    </UserControl.Styles>

</UserControl>