You have variety way to customize sign-in page. You can entirely modify the signin.html page with an HTML editor or decide its behavior just by web.config such as:
  • Customize Identity Providers
  • Customize Windows Authentication
  • Restrict to work only with specific domain
  • Restrict to work only with specific identify provider

Modern Theme





Classic Theme

 https://sites.google.com/a/shetabtech.com/sharepoint-live-authentication/features/signin-page/mobile2.png?attredirects=0