Append Gap
append-gap
The append-gap parameter sets the space between the base image and the append image. It defaults to 0, so the two images touch.
A whole number is pixels multiplied by dpr, capped at 4096. A decimal between 0 and 1 is a fraction of the base image instead, following the usual relative length rule.
The gap takes the pad fill first and then bg. With neither set it is transparent, or white on JPEG output.
