App.xaml

<Application x:Class="Encryptie_Tools.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:Encryptie_Tools"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
        <Style TargetType="Button">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Button">
                        <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" CornerRadius="10" BorderThickness="1.4">
                            <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Background" Value="#c6c6c6"/>
                </Trigger>
                <Trigger Property="IsPressed" Value="True">
                    <Setter Property="Background" Value="DarkGray"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Application.Resources>
</Application>