WPF 设置button样式，鼠标经过按钮字体变大

Button样式效果：

1.编写样式

 <Style x:Key="btn" TargetType="Button">
            <Setter Property="Margin" Value="5,5,5,5"></Setter>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Button">
                        <Grid>
                            <Border BorderThickness="1" Margin="10 0 10 0" VerticalAlignment="Center" HorizontalAlignment="Center" Width="100" Height="30" CornerRadius="5,5,5,5" Background="#3E98D7">
                                <TextBlock Grid.Column="1" Text="{TemplateBinding Content}" VerticalAlignment="Center" HorizontalAlignment="Center"  Foreground="White"></TextBlock>
                            </Border>
                        </Grid>
                        <ControlTemplate.Triggers>
                            <Trigger Property="Button.IsMouseOver"  Value="True">
                                <Setter Property="Opacity" Value="1" />
                                <Setter Property="FontSize" Value="13"></Setter>
                                <Setter Property="FontWeight" Value="Bold"></Setter>
                            </Trigger>
                            <Trigger Property="Button.IsEnabled" Value="False">
                                <Setter Property="Opacity" Value="0.5" />
                            </Trigger>
                            <Trigger Property="Button.IsEnabled" Value="True">
                                <Setter Property="Opacity" Value="1" />
                            </Trigger>
                         </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
</Style> <Style x:Key="btn" T