<Expander Header="在线设备" Foreground="#FFD6FFFF"  FontSize="18" IsExpanded="True" Style="{StaticResource ExpanderStyle1}" Background="#FF24B072"/>

Style="{StaticResource ExpanderStyle1}"

<Style x:Key="ExpanderStyle1" TargetType="{x:Type Expander}">
            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
            <Setter Property="Background" Value="Transparent"/>
            <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
            <Setter Property="VerticalContentAlignment" Value="Stretch"/>
            <Setter Property="BorderBrush" Value="#FF5CB0CF"/>
            <Setter Property="BorderThickness" Value="1"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type Expander}">
                        <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="5" SnapsToDevicePixels="true">
                            <Border.Background>
                                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                    <GradientStop Color="#FF2B92B0" Offset="0.242"/>
                                    <GradientStop Color="#FF5CB0CF" Offset="0.003"/>
                                </LinearGradientBrush>
                            </Border.Background>
                            <DockPanel>
                                <ToggleButton Height="35" x:Name="HeaderSite" ContentTemplate="{TemplateBinding HeaderTemplate}" ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}" Content="{TemplateBinding Header}" DockPanel.Dock="Top" Foreground="{TemplateBinding Foreground}" FontWeight="{TemplateBinding FontWeight}" FocusVisualStyle="{StaticResource ExpanderHeaderFocusVisual}" FontStyle="{TemplateBinding FontStyle}" FontStretch="{TemplateBinding FontStretch}" FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" IsChecked="{Binding IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="2" MinWidth="0" MinHeight="0" Padding="{TemplateBinding Padding}" Style="{StaticResource ExpanderDownHeaderStyle}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"/>

                                <ContentPresenter x:Name="ExpandSite" DockPanel.Dock="Bottom" Focusable="false" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" Visibility="Collapsed" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                            </DockPanel>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsExpanded" Value="true">
                                <Setter Property="Visibility" TargetName="ExpandSite" Value="Visible"/>
                            </Trigger>
                            <Trigger Property="ExpandDirection" Value="Right">
                                <Setter Property="DockPanel.Dock" TargetName="ExpandSite" Value="Right"/>
                                <Setter Property="DockPanel.Dock" TargetName="HeaderSite" Value="Left"/>
                                <Setter Property="Style" TargetName="HeaderSite" Value="{StaticResource ExpanderRightHeaderStyle}"/>
                            </Trigger>
                            <Trigger Property="ExpandDirection" Value="Up">
                                <Setter Property="DockPanel.Dock" TargetName="ExpandSite" Value="Top"/>
                                <Setter Property="DockPanel.Dock" TargetName="HeaderSite" Value="Bottom"/>
                                <Setter Property="Style" TargetName="HeaderSite" Value="{StaticResource ExpanderUpHeaderStyle}"/>
                            </Trigger>
                            <Trigger Property="ExpandDirection" Value="Left">
                                <Setter Property="DockPanel.Dock" TargetName="ExpandSite" Value="Left"/>
                                <Setter Property="DockPanel.Dock" TargetName="HeaderSite" Value="Right"/>
                                <Setter Property="Style" TargetName="HeaderSite" Value="{StaticResource ExpanderLeftHeaderStyle}"/>
                            </Trigger>
                            <Trigger Property="IsEnabled" Value="false">
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                            </Trigger>

                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <Style x:Key="FocusVisual">
            <Setter Property="Control.Template">
                <Setter.Value>
                    <ControlTemplate>
                        <Rectangle Margin="2" SnapsToDevicePixels="true" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" StrokeThickness="1" StrokeDashArray="1 2"/>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>