PreFluent.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sys="clr-namespace:System;assembly=mscorlib">
    <!-- Override system shape defaults -->
    <CornerRadius x:Key="ControlCornerRadius">0,0,0,0</CornerRadius>
    <CornerRadius x:Key="OverlayCornerRadius">0,0,0,0</CornerRadius>
    <!-- Override system borders -->
    <sys:Double x:Key="CheckBoxBorderThemeThickness">2</sys:Double>
    <sys:Double x:Key="RadioButtonBorderThemeThickness">2</sys:Double>
    <Thickness x:Key="ButtonBorderThemeThickness">2</Thickness>
    <Thickness x:Key="CalendarDatePickerBorderThemeThickness">2</Thickness>
    <Thickness x:Key="TimePickerBorderThemeThickness">2</Thickness>
    <sys:Double x:Key="ToggleSwitchOuterBorderStrokeThickness">2</sys:Double>
    <Thickness x:Key="RepeatButtonBorderThemeThickness">2</Thickness>
    <Thickness x:Key="ToggleButtonBorderThemeThickness">2</Thickness>
    <Thickness x:Key="TextControlBorderThemeThickness">2</Thickness>
    <sys:Double x:Key="PersonPictureEllipseBadgeStrokeThickness">2</sys:Double>
    <Thickness x:Key="ComboBoxBorderThemeThickness">2</Thickness>
    <Thickness x:Key="NumberBoxSpinButtonBorderThickness">0,2,2,2</Thickness>
</ResourceDictionary>