根据ViewModel的属性更改div类

public class MyViewModel : ObservableObject
{
    private string _myProperty;

    public string MyProperty
    {
        get { return _myProperty; }
        set { Set(ref _myProperty, value); }
    }
}

<Window.DataContext>
    <local:MyViewModel />
</Window.DataContext>

<Window.Resources>
    <local:MyViewModel x:Key="myViewModel" />
</Window.Resources>

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="auto" />
    </Grid.ColumnDefinitions>

    <Grid.RowDefinitions>
        <RowDefinition Height="auto" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>

    <TextBlock Grid.Column="0" Grid.ColumnSpan="2" Grid.Row="1" Text="Hello, World!" />

    <div Grid.Column="0" Grid.ColumnSpan="2" Grid.Row="0" 
        DataContext="{StaticResource myViewModel}"
        Style="{StaticResource MyStyle}" />

    <i:Interaction.Triggers>
        <i:EventTrigger EventName="PropertyChanged">
            <ei:CallMethodAction MethodName="UpdateDivClass" />
        </i:EventTrigger>
    </i:Interaction.Triggers>
</Grid>