MainWindow.xaml

<Window x:Class="PROJECT.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:PROJECT"
        mc:Ignorable="d"
        Title="PROJECT" Height="150" Width="300" Topmost="True" WindowStartupLocation="CenterScreen">
    <Window.Resources>
        <Style x:Key="ControlStyle1" TargetType="{x:Type Control}">
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Background">
                        <Setter.Value>
                            <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                <GradientStop Color="#FF124600" Offset="1"/>
                                <GradientStop Color="#FF289C00" Offset="0.307"/>
                            </LinearGradientBrush>
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid Opacity="0.85">
        <Button x:Name="button" HorizontalAlignment="Left" Margin="111,39,0,0" VerticalAlignment="Top" Width="75" Height="32" Click="button_Click" Content="Enable" Foreground="White" IsDefault="True" SnapsToDevicePixels="True" FocusVisualStyle="{DynamicResource ControlStyle1}" Style="{DynamicResource ControlStyle1}">
            <Button.Background>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="#FF124600" Offset="1"/>
                    <GradientStop Color="#FF289C00" Offset="0.307"/>
                </LinearGradientBrush>
            </Button.Background>
        </Button>
    </Grid>
</Window>