<!-- don't do this --->
<Border>
<Border.Effect>
<DropShadowEffect BlurRadius="25" ShadowDepth="0" Opacity="1"/>
</Border.Effect>
<TextBlock Text="This Text Will Be Blurry" />
</Border>
<!-- Do this instead -->
<Grid>
<Rectangle>
<Rectangle.Effect>
<DropShadowEffect BlurRadius="25" ShadowDepth="0" Opacity="1"/>
</Rectangle.Effect>
</Rectangle>
<TextBlock Text="This Text Will Be Crisp and Clear" />
</Grid>