WPF TextBox has Blue Outline while in focus - wpf

Question

So I am working on a program in WPF, and I made a textbox that has no border when out of focus, and (should) have a black line while focused. However, the line is showing up blue. I looked around Google, and nothing seems to work.
<Window x:Class="RequestApp.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
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:local="clr-namespace:RequestApp"
mc:Ignorable="d"
Title="MainWindow" Height="900.156" Width="1414.292">
<Window.Resources>
<Style TargetType="TextBox">
<Style.Triggers>
<Trigger Property="IsFocused" Value="True">
<Setter Property="BorderBrush" Value="Black" />
<Setter Property="Text" Value="Come Jam wit me man" />
</Trigger>
</Style.Triggers>
</Style>
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="7*"/>
<RowDefinition Height="18*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1067*"/>
<ColumnDefinition Width="433*"/>
</Grid.ColumnDefinitions>
<TextBox x:Name="Request" HorizontalAlignment="Left" Margin="37,130,0,0" BorderThickness="0" Text="Request" VerticalAlignment="Top" RenderTransformOrigin="-2.971,0.656" Height="39" Width="594" FontFamily="Modern Sans" FontSize="25" InputScope="Default" GotFocus="Request_GotFocus" LostFocus="Request_LostFocus" SelectionBrush="{x:Null}" BorderBrush="Black" Foreground="Gray"/>
</Grid>
PS: I don't know the first thing about XAML

Answer 1

Below is the default style for a TextBox. The behavior you are fighting is caused by these two ControlTemplate triggers - IsMouseOver and IsKeyboardFocused. Just edit the solid color brush definitions as you wish:
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
<Setter Property="BorderBrush" Value="{StaticResource TextBox.Static.Border}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="KeyboardNavigation.TabNavigation" Value="None"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="AllowDrop" Value="true"/>
<Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
<ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Opacity" TargetName="border" Value="0.56"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.MouseOver.Border}"/>
</Trigger>
<Trigger Property="IsKeyboardFocused" Value="true">
<Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox.Focus.Border}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsInactiveSelectionHighlightEnabled" Value="true"/>
<Condition Property="IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="SelectionBrush" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
</MultiTrigger>
</Style.Triggers>
</Style>

Answer 2

I found this question after searching for a way to get rid of the border in a WPF textbox what is shown blue and didn't fit into my design.
I have done this by setting the Border-Thickness to "0":
<TextBox x:Name="textBoxSearch" BorderThickness="0"/>