Fix3687 - card border white edges

[corvinsz]

I added a Card showcasing the linked bug in the demo app (make sure to remove it if this PR gets merged). When removing the Background="{TemplateBinding Background}" of the nested Card in the AdornerDecorator, the bug seems to be fixed.

Before:

After:

As shown with the text, ClearType is still maintained.

I'm not sure why there are 2 Borders in the AdornerDecorator in the first place, so any input on if this is breaking something is welcome.

Edit: this possibly fixes #3687 Display: 1080p monitor @150% scaling

[corvinsz]

• Added back the Background="{TemplateBinding Background}"
• Added Margin="1" to inset the Border (as you suggested) Result:

As it can be seen in the image above, the white edges/corners are still visible with the applied changes. This can be circumvented by applying the CornerRadius to the inner Border, which has already been done to the outer Border.

To be honest this still feels kinda hacky, but it appears to fix the issue:

P.S.: I want you thank you for your work. I really enjoy your live streams (or youtube videos rather, because I'm almost never up intime because I'm from the EU), they have taught me alot!