<Window x:Class="WpfApp1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApp1"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.Resources>
<Style TargetType="TextBox">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="Background" Value="Red"/>
<Setter Property="Foreground" Value="White"/>
</Trigger>
</Style.Triggers>
</Style>
</Window.Resources>
<TextBox Width="100" Height="20">
<TextBox.Text>
<Binding Path="InputText" UpdateSourceTrigger="PropertyChanged" >
<Binding.ValidationRules>
<local:InputRangeRule Max="100"/>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
</Window>