WhiteErase/WriteErase/ClassStyle/StyleGroupBox.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="GroupBox">
        <Style.Setters>
            <Setter Property="Foreground" Value="#498C51"/>
            <Setter Property="FontSize" Value="15"/>
            <Setter Property="FontWeight" Value="Bold"/>
            <Setter Property="BorderThickness" Value="0"/>
        </Style.Setters>
    </Style>
</ResourceDictionary>