XFEstudio/MyFirstRespo / XFEToolBoxInstaller/Resources/Style/Theme/LightTheme.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <SolidColorBrush x:Key="MainColor" Color="#9898e7"/>
    <SolidColorBrush x:Key="BackgroundColor" Color="White"/>
</ResourceDictionary>