I'm trying to secure my website using Azure AD and using the OpenID endpoints to redirect my users. I have been able so far to set up a custom branded login page (using a trial of Azure AD Premium) and been able to view my custom branding by adding a &whr=mydomain.onmicrosoft.com to the URL. Navigating to the site using the OpenID Connect flow does not show any custom branding.
Does Azure AD support OpenID flow with custom branding?
Yep. You simply need to specify your home realm using a different syntax. See http://www.cloudidentity.com/blog/2014/11/17/skipping-the-home-realm-discovery-page-in-azure-ad/