将不透明度设置为边框会更改内部内容的不透明度

<Border BorderBrush="Black" Background="#AFAFAF" Opacity="0.1" BorderThickness="1">
    <TextBlock Opacity="1" Text="{Binding Story}" Margin="25 15 25 15" Style="{StaticResource content}" Width="600" Foreground="#636363" />
</Border>
<Border BorderBrush="Black" Background="#AFAFAF