We have updated the sign-up and login user interface to keep up with current design trends and standards.
The login and sign up pages on any community URL will feature a split-screen user interface. The login form will be located on the left side, and image on the right side. Additionally Administrators can customize logo, background imagery and text above the background image.
You can always set up the background image from the default images or from any of the images from your community file library.
To learn how to change the image, check the help article: https://intercom.help/ideascale/en/articles/3367798-background-image-for-the-login-page