In the updated Blue theme, AppDesigner has the wrong colors

[davkean]

In the updated Blue theme, the app-designer left-hand bar is using the wrong colors, both the background and the highlight color are wrong:

Blue:

Light:

Dark:

It looks correct in the other themes.

Not sure if this is our bug or that they didn't update the colors that we're using.

[davkean]

This is where we added theming support: https://github.com/dotnet/project-system/pull/2158/files.