StTest/MyTests/Styles/Style.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    x:Class="MyTests.Style">

    <SolidColorBrush x:Key="TextColor" 
                     Color="White">
    </SolidColorBrush>
    
    <SolidColorBrush x:Key="color1" 
                     Color="#32353B">
    </SolidColorBrush>
    
    <SolidColorBrush x:Key="color2" 
                     Color="#2F3136">
    </SolidColorBrush>

    <SolidColorBrush x:Key="color3" 
                     Color="#FF44464D">
    </SolidColorBrush>

    <Style TargetType="Label">
        <Setter Property="Foreground" Value="White"/>
    </Style>

    <Style TargetType="TextBox">
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="BorderBrush" Value="Black"/>
        <Setter Property="Background" Value="#33363C"/>
    </Style>
    
    <Style TargetType="TextBlock">
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="Background" Value="{x:Null}"/>
    </Style>

    <Style TargetType="ComboBox">
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="BorderBrush" Value="Black"/>
        <Setter Property="Background" Value="#33363C"/>
    </Style>


    <Style TargetType="ComboBoxItem">
        <Setter Property="Background" Value="#33363C"/>
        <Setter Property="BorderBrush" Value="Black"/>
    </Style>


    <Style TargetType="Button">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border Name="Border" 
                            CornerRadius="15"
                            Background="#33363C"
                            BorderBrush="White" 
                            MouseEnter="MouseEnter" 
                            MouseLeave="MouseLeave">
                        <ContentPresenter HorizontalAlignment="Center" 
                                          VerticalAlignment="Center"/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Foreground" 
                Value="White"/>
    </Style>

    <Style x:Key="ScrollThumbs" TargetType="{x:Type Thumb}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <Grid x:Name="Grid">
                        <Border x:Name="Rectangle1" 
                                CornerRadius="10 0 0 10" 
                                HorizontalAlignment="Stretch" 
                                VerticalAlignment="Stretch" 
                                Width="Auto" 
                                Height="Auto" 
                                Background="{TemplateBinding Background}"/>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <!--SCROLLBARS-->
    <Style x:Key="{x:Type ScrollBar}" TargetType="{x:Type ScrollBar}">
        <Setter Property="Foreground" Value="#FF2D2D30"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ScrollBar}">
                    <Grid x:Name="GridRoot" Width="12" Background="{x:Null}">
                        <Track x:Name="PART_Track" Grid.Row="0" IsDirectionReversed="true" Focusable="False">
                            <Track.Thumb>
                                <Thumb x:Name="Thumb" Background="{TemplateBinding Foreground}" 
                                               Style="{DynamicResource ScrollThumbs}"/>
                            </Track.Thumb>
                            <Track.IncreaseRepeatButton>
                                <RepeatButton x:Name="PageUp" Command="ScrollBar.PageDownCommand" Opacity="0" Focusable="False"/>
                            </Track.IncreaseRepeatButton>
                            <Track.DecreaseRepeatButton>
                                <RepeatButton x:Name="PageDown" Command="ScrollBar.PageUpCommand" Opacity="0" Focusable="False"/>
                            </Track.DecreaseRepeatButton>
                        </Track>
                    </Grid>

                    <ControlTemplate.Triggers>
                        <Trigger SourceName="Thumb" Property="IsMouseOver" Value="true">
                            <Setter Value="{DynamicResource ButtonSelectBrush}" 
                                            TargetName="Thumb" Property="Background"/>
                        </Trigger>
                        <Trigger SourceName="Thumb" Property="IsDragging" Value="true">
                            <Setter Value="{DynamicResource DarkBrush}" TargetName="Thumb" Property="Background"/>
                        </Trigger>

                        <Trigger Property="IsEnabled" Value="false">
                            <Setter TargetName="Thumb" Property="Visibility" Value="Collapsed"/>
                        </Trigger>
                        <Trigger Property="Orientation" Value="Horizontal">
                            <Setter TargetName="GridRoot" Property="LayoutTransform">
                                <Setter.Value>
                                    <RotateTransform Angle="-90"/>
                                </Setter.Value>
                            </Setter>
                            <Setter TargetName="PART_Track" Property="LayoutTransform">
                                <Setter.Value>
                                    <RotateTransform Angle="-90"/>
                                </Setter.Value>
                            </Setter>
                            <Setter Property="Width" Value="Auto"/>
                            <Setter Property="Height" Value="12"/>
                            <Setter TargetName="Thumb" Property="Tag" Value="Horizontal"/>
                            <Setter TargetName="PageDown" Property="Command" Value="ScrollBar.PageLeftCommand"/>
                            <Setter TargetName="PageUp" Property="Command" Value="ScrollBar.PageRightCommand"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>