Change ComboBox border color - wpf

Question

I try to change my ComboBox border color.
This is the style that i am using:
<Style x:Key="ComboBoxStyle1" TargetType="{x:Type ComboBox}" >
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
<Setter Property="TextElement.Foreground" Value="Black"/>
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<ToggleButton x:Name="ToggleButton" Grid.Column="2"
ClickMode="Press" Focusable="False"
IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
Template="{StaticResource ComboBoxToggleButtonTemplate}"/>
<ContentPresenter x:Name="ContentSite" Margin="5, 3, 23, 3" IsHitTestVisible="False"
HorizontalAlignment="Left" VerticalAlignment="Center"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"/>
<TextBox x:Name="PART_EditableTextBox" Margin="3, 3, 23, 3"
IsReadOnly="{TemplateBinding IsReadOnly}"
Visibility="Hidden" Background="Transparent"
HorizontalAlignment="Left" VerticalAlignment="Center"
Focusable="True" >
<TextBox.Template>
<ControlTemplate TargetType="{x:Type TextBox}" >
<Border x:Name="PART_ContentHost" Focusable="False" />
</ControlTemplate>
</TextBox.Template>
</TextBox>
<!-- Popup showing items -->
<Popup x:Name="Popup" Placement="Bottom"
Focusable="False" AllowsTransparency="True"
IsOpen="{TemplateBinding IsDropDownOpen}"
PopupAnimation="Slide" >
<Grid x:Name="DropDown" SnapsToDevicePixels="True"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder" Background="Transparent" Margin="0, 1, 0, 0"
CornerRadius="0" BorderThickness="1,1,1,1"
BorderBrush="{StaticResource ComboBoxNormalBorderBrush}"/>
<ScrollViewer Margin="4" SnapsToDevicePixels="True">
<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="False">
<Setter Property="MinHeight" TargetName="DropDownBorder" Value="95"/>
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="TextElement.Foreground" Value="{StaticResource ComboBoxDisabledForegroundBrush}"/>
</Trigger>
<Trigger Property="IsGrouping" Value="True">
<Setter Property="ScrollViewer.CanContentScroll" Value="False"/>
</Trigger>
<Trigger Property="IsEditable" Value="True">
<Setter Property="KeyboardNavigation.IsTabStop" Value="False"/>
<Setter Property="Visibility" TargetName="PART_EditableTextBox" Value="Visible"/>
<Setter Property="Visibility" TargetName="ContentSite" Value="Hidden"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
I try to change all the properties but still my ComboBox border color is white:
I also try to define the color inside my ComboBox controller or via code behind.
Update
I put this code:
<Border BorderBrush="Red" BorderThickness="3" />
And this is the result:
As you can see i still have the white color that i want to remove.

Answer 1

You can add your which is the root of your ControlTemplate to Border:
<ControlTemplate TargetType="{x:Type ComboBox}">
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<Grid>
<!--your template is here-->
</Grid>
</Border>
<!--etc-->