Fixes #29176 (closed).
Had to do some updating to a few things to make this work. Not sure how best to clean it up yet, but this at least restores the functionality. Making multiple background-images work without a bunch of duplicate mess is the tricky part here.
- Updates the
gradient-bg()mixin to include another parameter, a$foreground"background image" that is put on top of the gradient. - Adds a ton of
@ifstatements to handle the image swapping. - Adds a new variable while I'm at it for
$form-switch-bg-size.