App.xaml

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="SampleWebView.Avalonia.App">
    <Application.Resources>
        <Thickness x:Key="TextControlBorderThemeThickness">0</Thickness>
        <Thickness x:Key="TextControlBorderThemeThicknessFocused">0</Thickness>
        <Thickness x:Key="TextControlThemePadding">15,10,15,8</Thickness>
    </Application.Resources>
    <Application.Styles>
        <FluentTheme />
    </Application.Styles>
</Application>