Based on what I've already heard, I'm not optimistic this can be done, but I'll throw it out there anyway: Other than the logo, is there any way to customize the intermediated authentication pages? The idea here is to allow anonymous access to the SharePoint server, and if/when necessary, have the server handle the authentication. When using Core everything works as expected. My app developers, are trying to maintain a particular look and feel, including at the authentication page. I suspect my hands may be tied here. I know by modifying the sign-in page I have some flexibility, however, I'm not sure whether that extends into an already established session. I'm curious as to whether anyone had to deal with this, and what was your solution. Thanks