fis/fis.Upgrader/App.axaml

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="fis.Upgrader.App">
    <Application.Styles>
        <FluentTheme Mode="Light"/>
    </Application.Styles>
</Application>