Frederic – if you’re working with the standard login page (login.html) you can find the file in the /theme folder and update the HTML and CSS as much as you want. It’s easiest to put the images in /theme/img and reference that.
If you’re using a custom login page/widget, then you can create a new page layout and apply that to only the login page (so the other pages keep using default ones)
Thanks, Marshall. My question was part of a larger effort to copy the styling of an earlier Mx7 app into a new Mx8 app. Turns out, what I had to do was this: