看效果

WPF 精修篇 获取系统颜色和字体样式_WPF

<Grid>
        <Rectangle Fill="{DynamicResource {x:Static SystemColors.DesktopBrushKey}}" HorizontalAlignment="Left" Height="76" Margin="85,70,0,0" Stroke="Black" VerticalAlignment="Top" Width="243">
       
        </Rectangle>
        <TextBlock Text=" 文本" FontFamily="{DynamicResource {x:Static SystemFonts.CaptionFontFamily}}" FontSize="{DynamicResource {x:Static SystemFonts.CaptionFontSize}}" FontWeight="{DynamicResource {x:Static SystemFonts.CaptionFontWeight}}"></TextBlock>
    </Grid>

rectangle的fill 跟着窗体变化